BACKGROUND The benefit of adjuvant chemotherapy(ACT)for patients with no evidence of disease after pulmonary metastasis resection(PM)from colorectal cancer(CRC)remains controversial.AIM To assess the efficacy of ACT i...BACKGROUND The benefit of adjuvant chemotherapy(ACT)for patients with no evidence of disease after pulmonary metastasis resection(PM)from colorectal cancer(CRC)remains controversial.AIM To assess the efficacy of ACT in patients after PM resection for CRC.METHODS This study included 96 patients who underwent pulmonary metastasectomy for CRC at a single institution between April 2008 and July 2023.The primary end-point was overall survival(OS);secondary endpoints included cancer-specific survival(CSS)and disease-free survival(DFS).An inverse probability of treat-ment-weighting(IPTW)analysis was conducted to address indication bias.Sur-vival outcomes compared using Kaplan-Meier curves,log-rank test,Cox regre-ssion and confirmed by propensity score-matching(PSM).RESULTS With a median follow-up of 27.5 months(range,18.3-50.4 months),the 5-year OS,CSS and DFS were 72.0%,74.4%and 51.3%,respectively.ACT had no significant effect on OS after PM resection from CRC[original cohort:P=0.08;IPTW:P=0.15].No differences were observed for CSS(P=0.12)and DFS(P=0.68)between the ACT and non-ACT groups.Multivariate analysis showed no association of ACT with better survival,while sublobar resection(HR=0.45;95%CI:0.20-1.00,P=0.049)and longer disease-free interval(HR=0.45;95%CI:0.20-0.98,P=0.044)were associated with improved survival.CONCLUSION ACT does not improve survival after PM resection for CRC.Further well-designed randomized controlled trials are needed to determine the optimal ACT regimen and duration.展开更多
This article presents a novel optimization approach called RSWTLBO for accurately identifying unknown parameters in photovoltaic(PV)models.The objective is to address challenges related to the detection and maintenanc...This article presents a novel optimization approach called RSWTLBO for accurately identifying unknown parameters in photovoltaic(PV)models.The objective is to address challenges related to the detection and maintenance of PV systems and the improvement of conversion efficiency.RSWTLBO combines adaptive parameter w,Single Solution Optimization Mechanism(SSOM),and Weight Probability Exploration Strategy(WPES)to enhance the optimization ability of TLBO.The algorithm achieves a balance between exploitation and exploration throughout the iteration process.The SSOM allows for local exploration around a single solution,improving solution quality and eliminating inferior solutions.The WPES enables comprehensive exploration of the solution space,avoiding the problem of getting trapped in local optima.The algo-rithm is evaluated by comparing it with 10 other competitive algorithms on various PV models.The results demonstrate that RSWTLBO consistently achieves the lowest Root Mean Square Errors on single diode models,double diode models,and PV module models.It also exhibits robust performance under varying irradiation and temperature conditions.The study concludes that RSWTLBO is a practical and effective algorithm for identifying unknown parameters in PV models.展开更多
BACKGROUND Esophageal variceal bleeding is a severe complication associated with liver cirrhosis and typically necessitates endoscopic hemostasis.The current standard treatment is endoscopic variceal ligation(EVL),and...BACKGROUND Esophageal variceal bleeding is a severe complication associated with liver cirrhosis and typically necessitates endoscopic hemostasis.The current standard treatment is endoscopic variceal ligation(EVL),and Western guidelines recom-mend antibiotic prophylaxis following hemostasis.However,given the impro-vements in prognosis for variceal bleeding due to advancements in the management of bleeding and treatments of liver cirrhosis and the global concerns regarding the emergence of multidrug-resistant bacteria,there is a need to reassess the use of routine antibiotic prophylaxis after hemostasis.AIM To evaluate the effectiveness of antibiotic prophylaxis in patients treated for EVL.METHODS We conducted a 13-year observational study using the Tokushukai medical database across 46 hospitals.Patients were divided into the prophylaxis group(received antibiotics on admission or the next day)and the non-prophylaxis group(did not receive antibiotics within one day of admission).The primary outcome was composed of 6-wk mortality,4-wk rebleeding,and 4-wk spontaneous bacterial peritonitis(SBP).The secondary outcomes were each individual result and in-hospital mortality.A logistic regression with inverse probability of treatment weighting was used.A subgroup analysis was conducted based on the Child-Pugh classification to determine its influence on the primary outcome measures,while sensitivity analyses for antibiotic type and duration were also performed.RESULTS Among 980 patients,790 were included(prophylaxis:232,non-prophylaxis:558).Most patients were males under the age of 65 years with a median Child-Pugh score of 8.The composite primary outcomes occurred in 11.2%of patients in the prophylaxis group and 9.5%in the non-prophylaxis group.No significant differences in outcomes were observed between the groups(adjusted odds ratio,1.11;95%confidence interval,0.61-1.99;P=0.74).Individual outcomes such as 6-wk mortality,4-wk rebleeding,4-wk onset of SBP,and in-hospital mortality were not significantly different between the groups.The primary outcome did not differ between the Child-Pugh subgroups.Similar results were observed in the sensitivity analyses.CONCLUSION No significant benefit to antibiotic prophylaxis for esophageal variceal bleeding treated with EVL was detected in this study.Global reassessment of routine antibiotic prophylaxis is imperative.展开更多
This paper proposes a novel method for estimating the sparse inverse covariance matrixfor longitudinal data with informative dropouts. Based on the modified Cholesky decomposition,the sparse inverse covariance matrix ...This paper proposes a novel method for estimating the sparse inverse covariance matrixfor longitudinal data with informative dropouts. Based on the modified Cholesky decomposition,the sparse inverse covariance matrix is modelled by the autoregressive regression model,which guarantees the positive definiteness of the covariance matrix. To account for the informativedropouts, we then propose a penalized estimating equation method using the inverse probabilityweighting approach. The informative dropout propensity parameters are estimated by the generalizedmethod of moments. The asymptotic properties are investigated for the resulting estimators.Finally, we illustrate the effectiveness and feasibility of the proposed method through Monte Carlosimulations and a practical application.展开更多
Abstract:Background:The pTNM staging system is widely recognized as the most effective prognostic indicator for cancer.The latest update of this staging system introduced a new pathological staging system(ypTNM)for pa...Abstract:Background:The pTNM staging system is widely recognized as the most effective prognostic indicator for cancer.The latest update of this staging system introduced a new pathological staging system(ypTNM)for patients receiving neoadjuvant chemoradiotherapy(NACRT).However,whether the prognostic value of the ypTNM staging system for rectal cancer is similar to that of the pTNM staging system remains unclear.This study was conducted to compare the ypTNM and pTNM staging systems in terms of their prognostic value for patients with nonmetastatic rectal cancer undergoing proctectomy.Material and Methods:This study was conducted at a large teaching hospital.Between January 2014 and December 2022,542 patients with rectal cancer were analyzed(median follow-up period,60 months;range,6–105 months).Of them,258 and 284 were included in the pTNM and ypTNM groups,respectively.Inverse probability of treatment weighting(IPTW)was performed to account for the effects of confounders.Cox proportional-hazards regression was performed for the between-group comparison of overall survival(OS).Results:The crude model revealed that OS was similar between the two groups(p=0.607).After performing IPTW,we found that patients with the same ypTNM-and pTNM-classified stages had similar overall survival(hazard ratio=1.15;95%CI=0.76–1.73;p=0.5074).Conclusions:For patients with rectal cancer who have received preoperative NACRT,the prognostic value of ypTNM staging appears to be similar to that of pTNM staging,mostly because of the downstaging effect of neoadjuvant chemoradiotherapy。展开更多
The function of the air target threat evaluation （TE） is the foundation for weapons allocation and senor resources management within the surface air defense. The multi-attribute evaluation methodology is utilized to...The function of the air target threat evaluation （TE） is the foundation for weapons allocation and senor resources management within the surface air defense. The multi-attribute evaluation methodology is utilized to address the issue of the TE in which the tactic features of the detected target are treated as evaluation attributes. Meanwhile, the intuitionistic fuzzy set （IFS） is employed to deal with information uncertainty in the TE process. Furthermore, on the basis of the entropy weight and inclusion-comparison probability, a hybrid TE method is developed. In order to accommodate the demands of naturalistic decision making, the proposed method allows air defense commanders to express their intuitive opinions besides incorporating into the threat features of the detected target. An illustrative example is provided to indicate the feasibility and advantage of the proposed method.展开更多
Estimating the intention of space objects plays an important role in air-craft design,aviation safety,military and otherfields,and is an important refer-ence basis for air situation analysis and command decision-making...Estimating the intention of space objects plays an important role in air-craft design,aviation safety,military and otherfields,and is an important refer-ence basis for air situation analysis and command decision-making.This paper studies an intention estimation method based on fuzzy theory,combining prob-ability to calculate the intention between two objects.This method takes a space object as the origin of coordinates,observes the target’s distance,speed,relative heading angle,altitude difference,steering trend and etc.,then introduces the spe-cific calculation methods of these parameters.Through calculation,values are input into the fuzzy inference model,andfinally the action intention of the target is obtained through the fuzzy rule table and historical weighted probability.Ver-ified by simulation experiment,the target intention inferred by this method is roughly the same as the actual behavior of the target,which proves that the meth-od for identifying the target intention is effective.展开更多
In this article, to improve the doubly robust estimator, the nonlinear regression models with missing responses are studied. Based on the covariate balancing propensity score (CBPS), estimators for the regression coef...In this article, to improve the doubly robust estimator, the nonlinear regression models with missing responses are studied. Based on the covariate balancing propensity score (CBPS), estimators for the regression coefficients and the population mean are obtained. It is proved that the proposed estimators are asymptotically normal. In simulation studies, the proposed estimators show improved performance relative to usual augmented inverse probability weighted estimators.展开更多
It is known that conditional independence is a quite basic assumption in many fields of statistics. How to test its validity is of great importance and has been extensively studied by the literature. Nevertheless, all...It is known that conditional independence is a quite basic assumption in many fields of statistics. How to test its validity is of great importance and has been extensively studied by the literature. Nevertheless, all of the existing methods focus on the case that data are fully observed, but none of them seems having taken into account of the scenario when missing data are present. Motivated by this, this paper develops two testing statistics to handle such a situation relying on the idea of inverse probability weighted and augmented inverse probability weighted techniques. The asymptotic distributions of the proposed statistics are also derived under the null hypothesis. The simulation studies indicate that both testing statistics perform well in terms of size and power.展开更多
BACKGROUND Right-sided ligamentum teres(RSLT)is often associated with portal venous anomalies(PVA)and is regarded as a concerning feature for hepatobiliary intervention.Most studies consider RSLT to be one of the caus...BACKGROUND Right-sided ligamentum teres(RSLT)is often associated with portal venous anomalies(PVA)and is regarded as a concerning feature for hepatobiliary intervention.Most studies consider RSLT to be one of the causes of left-sided gallbladder(LGB),leading to the hypothesis that LGB must always be present with RSLT.However,some cases have shown that right-sided gallbladder(RGB)can also be present in livers with RSLT.AIM To highlight the rare variation that RSLT may not come with LGB and to determine whether ligamentum teres(LT)or gallbladder location is reliable to predict PVA.METHODS This study retrospectively assessed 8552 contrast-enhanced abdominal computed tomography examinations from 2018 to 2021[4483 men,4069 women;mean age,59.5±16.2(SD)years].We defined the surrogate outcome as major PVAs.The cases were divided into 4 subgroups according to gallbladder and LT locations.On one hand,we analyzed PVA prevalence by LT locations using gallbladder location as a controlled variable(n=36).On the other hand,we controlled LT location and computed PVA prevalence by gallbladder locations(n=34).Finally,we investigated LT location as an independent factor of PVA by using propensity score matching(PSM)and inverse probability of treatment weighting(IPTW).RESULTS We found 9 cases of RSLT present with RGB.Among the LGB cases,RSLT is associated with significantly higher PVA prevalence than typical LT[80.0%vs 18.2%,P=0.001;OR=18,95%confidence interval(CI):2.92-110.96].When RSLT is present,we found no statistically significant difference in PVA prevalence for RGB and LGB cases(88.9%vs 80.0%,P>0.99).Both PSM and IPTW yielded balanced cohorts in demographics and gallbladder locations.The RSLT group had a significantly higher PVA prevalence after adjusted by PSM(77.3%vs 4.5%,P<0.001;OR=16.27,95%CI:2.25-117.53)and IPTW(82.5%vs 4.7%,P<0.001).CONCLUSION RSLT doesn't consistently coexist with LGB.RSLT can predict PVA independently while the gallbladder location does not serve as a sufficient predictor.展开更多
<strong>Background:</strong> Acute Myeloid leukemia (AML) is the most prominent acute leukemia in adults. In the United States, we experience over 20,000 cases per year. Over the past decade, improvements ...<strong>Background:</strong> Acute Myeloid leukemia (AML) is the most prominent acute leukemia in adults. In the United States, we experience over 20,000 cases per year. Over the past decade, improvements in the diagnosis of subtypes of AML and advances in therapeutic approaches have improved the outlook for patients with AML. However, despite these advancements, the survival rate among patients who are less than 65 years of age is only 40 percent. <strong>Purpose:</strong> The purpose of the paper is to study if there exists any significant difference in the survival probabilities of male and female AML patients. Also, we want to investigate if there is any parametric probability distribution that best fits the male and female patient survival and compare the survival probabilities with the non-parametric Kaplan-Meier (KM) method. <strong>Methods:</strong> We used both parametric and non-parametric statistical methods to perform the survival analysis to assess the survival probabilities of 2015 patients diagnosed with AML.<strong> Results:</strong> We found evidence of a statistically significant difference between the mean survival time of male and female patients diagnosed with AML. We performed parametric survival analysis and found a Generalized Extreme Value (GEV) distribution best fitting the data of the survival time for male and female patients. We then estimated the survival probabilities and compared them with the frequently used non-parametric Kaplan-Meier (KM) survival method. <strong>Conclusion:</strong> The comparison between the survival probability estimates of the two methods revealed a better survival probability estimate by the parametric method than the Kaplan-Meier. We also compared the median survival time of male and female patients individually with descriptive, parametric, and non-parametric methods of analysis. The parametric survival analysis is more robust and efficient because it is based on a well-defined parametric probabilistic distribution, hence preferred over the non-parametric Kaplan-Meier estimate. This study offers therapeutic significance for further enhancement to treat patients with Acute Myeloid Leukemia.展开更多
Under probability weighting,entrepreneurs with skewness preference tend to seek rightskewed and avoid left-skewed risks.We show that Chinese firms managed by CEOs with professional epidemic experience,i.e.,who previou...Under probability weighting,entrepreneurs with skewness preference tend to seek rightskewed and avoid left-skewed risks.We show that Chinese firms managed by CEOs with professional epidemic experience,i.e.,who previously experienced the outbreak of SARS during their tenure as high level executives,have a lower stock price crash risk measured by the negative skewness of stock prices in subsequent periods.In particular,those firms intentionally avoid stock price crashes by adopting more conservative strategies in decisionmaking.Overall,we provide the first evidence on the unintended effect of entrepreneurs'subjective judgments of the probabilities of disease outbreaks on financial market stability.These have long-term implications for the financial system.展开更多
Background:Laparoscopic resection(LR)of perihilar cholangiocarcinoma(pCCA)is still in the exploratory stage due to its exacting technical requirements,and its feasibility remains controversial.The objective of this st...Background:Laparoscopic resection(LR)of perihilar cholangiocarcinoma(pCCA)is still in the exploratory stage due to its exacting technical requirements,and its feasibility remains controversial.The objective of this study was to compare the short-and long-term outcomes of LR and open resection(OR)of pCCA.Methods:This study analyzed the data of pCCA patients who underwent LR or OR from January 2012 to January 2020 at Southwest Hospital.Inverse probability of treatment weighting(IPTW)and propensity score matching(PSM)were used to balance the baseline characteristics between the LR and OR groups.The short-and long-term outcomes were compared between the LR and OR groups.Results:Forty-five patients in the LR group and 243 in the OR group were analyzed.After IPTW and PSM,the amount of intraoperative blood loss,incidence of surgical site infections(SSIs),length of stay(LOS),and number of perioperative blood transfusions(PBTs)were significantly lower in the LR group than in the OR group(after IPTW:P<0.001,P=0.009,P=0.01,P<0.001 respectively;after PSM:P<0.001,P=0.003,P=0.03,P=0.04 respectively).Only after IPTW was the 30-day mortality rate significantly lower in the LR group than in the OR group(P=0.005).There was no significant difference in overall survival(OS)or recurrence-free survival(RFS)between the two groups after IPTW or PSM.Conclusions:LR of pCCA is an achievable procedure whose long-term outcomes are similar to those of OR,and LR outperforms OR in short-term outcomes such as intraoperative blood loss,SSI,LOS,30-day mortality,and PBTs.It is believed that it is safe and feasible to treat pCCA with LR after rigorous patient selection.展开更多
Attrition is a common challenge in statistical analysis for longitudinal or multi-stage cross-sectional studies.While strategies to reduce attrition should ideally be implemented during the study design phase,they rem...Attrition is a common challenge in statistical analysis for longitudinal or multi-stage cross-sectional studies.While strategies to reduce attrition should ideally be implemented during the study design phase,they remain common in real-world research,necessitating statistical methods to address them.Tra-ditional approaches like multiple imputation(MI)and inverse probability weighting(IPW)rely on the assumption that data is missing at random(MAR),which is not always plausible.Recent developments in machine learn-ing(ML)based methods offer promising alternatives because of their ability to capture complex patterns in data and handle non-linear relationships more effectively.This study examines four ML-based imputation methods to ac-count for attrition and compares them with conventional MI and IPW in a two-stage epilepsy population-based prevalence survey involving 56,425 par-ticipants.Simulated attrition levels from 5%to 50%were applied following the MAR mechanism to assess the performance of the different methods.This was replicated 100 times using different random seeds.Results showed that bias increased with an increase in attrition levels.Complete case analysis had the largest bias in all scenarios.k-nearest neighbor(KNN)and sequential KNN(sKNN)performed similarly to MI under MAR but exhibited less bias than MI and IPW when data were MNAR.While IPW performed similarly to MI under MAR,it had greater bias under MNAR.Both missForest and the MI implemented using random forest were outperformed by sKNN and KNN.We have demonstrated that even a small attrition proportion of 5%can sig-nificantly bias estimates if not properly addressed.While MI is still the most preferred for missing data assuming MAR,ML methods,particularly sKNN and KNN demonstrated potential for addressing attrition when data are MNAR.Choosing the appropriate method to address missing data should be preceded by an evaluation of different available methods that could be suitable for the data being analysed.Future research should explore ML methods in various study designs and consider integrating ML into the very robust MI framework to improve prediction accuracy for missing data due to attrition.展开更多
This papcr investigates a Parcto optimal insurancc contract design problcm within a behavioral finance framework.In this context,the insured evaluates contracts using the rank-dependent utility(RDU,for short)theory,wh...This papcr investigates a Parcto optimal insurancc contract design problcm within a behavioral finance framework.In this context,the insured evaluates contracts using the rank-dependent utility(RDU,for short)theory,while the insurer applies the expected value premium principle.The analysis incorporates the incentive compatibility constraint,ensuring that the contracts,called moral-hazard-free,are free from the moral hazard issues identified in Bernard et al.[4].Initially,the problem is formulated as a nonconcave maximization problem involving Choquet expectation.It is then transformed into a quantile optimization problem and addrcssed using thc calculus of variations mcthod.The optimal contracts are characterized by a double-obstacle ordinary differential equation for a semi-linear second-order elliptic operator with nonlocal boundary conditions,which seems new in the financial economics literature.We present a straightforward numerical scheme and a numerical example to compute the optimal contracts.Let and mo represent the relative safety loading and the mass of the potential loss at O,respectively.We discover that every moral-hazard-free contract is optimal for infinitely many RDU-insured individuals if 0<θ<m_(0)/1-m_(0).Conversely,certain contracts,such as the full coverage contract,are never optimal for any RDU-insured individual ifθ>m_(0)/1-m_(0)Additionally,we derive all the Pareto optimal contracts when either the compensation or the retention violates the monotonicity constraint.展开更多
Background:Burns resulting from assaults account for considerable morbidity and mortality among patients with burn injuries around the world.However,it is still unclear whether unfavorable clinical outcomes are associ...Background:Burns resulting from assaults account for considerable morbidity and mortality among patients with burn injuries around the world.However,it is still unclear whether unfavorable clinical outcomes are associated primarily with the severity of the injuries.To elucidate the direct relationship between burns resulting from assaults and mortality and/or length of hospital stays,we performed this study with the hypothesis that burns from assault would be independently associated with fewer hospital-free days than would burns from other causes,regardless of the severity of burn injuries.Methods:We conducted a retrospective cohort study,using a city-wide burn registry(1996–2017)accounting for 14 burn centers in Tokyo,Japan.Patients who arrived within 24 hours after injury were included,and those with self-inflicted burn injuries were excluded.Patients were divided into two groups according to mechanism of burns(assault vs.accident),and the number of hospitalfree days until day 30 after injury(a composite of in-hospital death and hospital length of stay)was compared between the groups.To estimate the probability that an injury would be classified as an assault,we calculated propensity scores,using multivariate logistic regression analyses adjusted for known outcome predictors.We also performed an inverse probability weighting(IPW)analysis to compare adjusted numbers of hospital-free days.Results:Of 7419 patients in the registry with burn injuries during the study period,5119 patients were included in this study.Of these,113(2.2%)were injured as a result of assault;they had significantly fewer hospital-free days than did those with burns caused by accident(18[27]vs.24[20]days;coefficient=−3.4[−5.5 to−1.3]days;p=0.001).IPW analyses similarly revealed the independent association between assault burn injury and fewer hospital-free days(adjusted coefficient=−0.6[−1.0 to−0.1]days;p=0.009).Conclusions:Burn from assault was independently associated with fewer hospital-free days,regardless of the severity of burn injuries.The pathophysiological mechanism underlying the relationship should be further studied in a prospective observational study.展开更多
Objective:This study conducted inverse probability of treatment weighting(IPTW)survival analysis to examine survival in pancreatic adenocarcinoma patients.Methods:In this population-based study,data from the Surveilla...Objective:This study conducted inverse probability of treatment weighting(IPTW)survival analysis to examine survival in pancreatic adenocarcinoma patients.Methods:In this population-based study,data from the Surveillance,Epidemiology,and End Results program of the United States were analyzed to identify patients diagnosed with adenocarcinoma of the pancreas 2004 to 2014.Differences in survival rates were examined among patients who underwent pancreatectomy alone,radiotherapy alone,and those who had pancreatectomy plus adjuvant radiotherapy.Kaplan-Meier estimates and Cox proportional hazards models with the IPTW were performed to determine the effect of different treatments on overall and cancer-specific survival.This study was approved by the Ethics Review Board of Weifang Medical University.Results:A total of 8191 patients were included,with 3409 taking pancreatectomy only,2865 taking radiotherapy only,and 1917 taking pancreatectomy plus adjuvant radiotherapy.Patients who received surgery plus adjuvant radiotherapy had statistically a higher survival rate than those who received the other 2 treatments.Survival analysis with the IPTW for the 3 different groups showed that the difference in median overall survival time among these patient groups was significant.Conclusion:Using IPTW survival analysis,the present study shows that surgery with adjuvant radiotherapy is significantly associated with improved overall and cancer-specific survival among patients with pancreatic adenocarcinoma.展开更多
Doubly robust(DR)methods that employ both the propensity score and outcome models are widely used to estimate the causal effect of a treatment and generally outperform those methods only using the propensity score or ...Doubly robust(DR)methods that employ both the propensity score and outcome models are widely used to estimate the causal effect of a treatment and generally outperform those methods only using the propensity score or the outcome model.However,without appropriately chosen the working models,DR estimators may substantially lose efficiency.In this paper,based on the augmented inverse probability weighting procedure,we derive a new estimating equation for the causal effect by the strategy of combining estimating equations.The resulting estimator by solving the new estimating equation retains doubly robust and can improve the efficiency under the misspecification of conditional mean working model.We further show the large sample properties of the proposed estimator under some regularity conditions.Through simulation experiments and a real data analysis,we illustrate that the proposed method is competitive with its competitors,which is in line with those implied by the asymptotic theory.展开更多
We mainly focus on regression estimation in a longitudinal study with nonignorable intermittent nonresponse and dropout.To handle the identifiability issue,we take a time-independent covariate as nonresponse instrumen...We mainly focus on regression estimation in a longitudinal study with nonignorable intermittent nonresponse and dropout.To handle the identifiability issue,we take a time-independent covariate as nonresponse instrument which is independent of nonresponse propensity conditioned on other covariates and responses to ensure the identifiability of nonresponse propensity.The nonresponse propensity is assumed to be a parametric model,and the corresponding parameters are estimated by using the generalized method of moments approach.Then the marginal response means are estimated by inverse probability weighting method.Furthermore,to improve the robustness of estimators,we derive an augmented inverse probability weighting estimator which is shown to be consistent and asymptotically normally distributed.Simulation studies and a real-data analysis show that the proposed approach yields highly efficient estimators.展开更多
Background:Metabolic dysfunction-associated fatty liver disease(MAFLD)is a common liver disease,the risk of which can be increased by poor diet.The objective of this study was to evaluate the associations between food...Background:Metabolic dysfunction-associated fatty liver disease(MAFLD)is a common liver disease,the risk of which can be increased by poor diet.The objective of this study was to evaluate the associations between food items and MAFLD,and to propose reasonable dietary recommendations for the prevention of MAFLD.Methods:Physical examination data were collected from April 2015 through August 2017 at Nanping First Hospital(n=3,563).Dietary intakes were assessed using a semi-quantitative food frequency questionnaire.The association between food intake and the risk of MAFLD was assessed by using the inverse probability weighted propensity score.Results:Beverages(soft drinks and sugar-sweetened beverages)and instant noodles were positively associated with MAFLD risk,adjusting for smoking,drinking,tea intake,and weekly hours of physical activity[adjusted odds ratio(ORadjusted):1.568;P=0.044;ORadjusted:4.363;P=0.001].Milk,tubers,and vegetables were negatively associated with MAFLD risk(ORadjusted:0.912;P=0.002;ORadjusted:0.633;P=0.007;ORadjusted:0.962;P=0.028).In subgroup analysis,the results showed that women[odds ratio(OR):0.341,95%confidence interval(CI):0.172–0.676]had a significantly lower risk of MAFLD through consuming more tubers than men(OR:0.732,95%CI:0.564–0.951).Conclusions:These findings suggest that reducing consumption of beverages(soft drinks and sugar-sweetened beverages)and instant noodles,and consuming more milk,vegetables,and tubers may reduce the risk of MAFLD.展开更多
基金Supported by the National Project for Clinical Key Specialty Development.
文摘BACKGROUND The benefit of adjuvant chemotherapy(ACT)for patients with no evidence of disease after pulmonary metastasis resection(PM)from colorectal cancer(CRC)remains controversial.AIM To assess the efficacy of ACT in patients after PM resection for CRC.METHODS This study included 96 patients who underwent pulmonary metastasectomy for CRC at a single institution between April 2008 and July 2023.The primary end-point was overall survival(OS);secondary endpoints included cancer-specific survival(CSS)and disease-free survival(DFS).An inverse probability of treat-ment-weighting(IPTW)analysis was conducted to address indication bias.Sur-vival outcomes compared using Kaplan-Meier curves,log-rank test,Cox regre-ssion and confirmed by propensity score-matching(PSM).RESULTS With a median follow-up of 27.5 months(range,18.3-50.4 months),the 5-year OS,CSS and DFS were 72.0%,74.4%and 51.3%,respectively.ACT had no significant effect on OS after PM resection from CRC[original cohort:P=0.08;IPTW:P=0.15].No differences were observed for CSS(P=0.12)and DFS(P=0.68)between the ACT and non-ACT groups.Multivariate analysis showed no association of ACT with better survival,while sublobar resection(HR=0.45;95%CI:0.20-1.00,P=0.049)and longer disease-free interval(HR=0.45;95%CI:0.20-0.98,P=0.044)were associated with improved survival.CONCLUSION ACT does not improve survival after PM resection for CRC.Further well-designed randomized controlled trials are needed to determine the optimal ACT regimen and duration.
基金supported in part by the Natural Science Foundation of Zhejiang Province(LTGS23E070001)National Natural Science Foundation of China(62076185,62301367).
文摘This article presents a novel optimization approach called RSWTLBO for accurately identifying unknown parameters in photovoltaic(PV)models.The objective is to address challenges related to the detection and maintenance of PV systems and the improvement of conversion efficiency.RSWTLBO combines adaptive parameter w,Single Solution Optimization Mechanism(SSOM),and Weight Probability Exploration Strategy(WPES)to enhance the optimization ability of TLBO.The algorithm achieves a balance between exploitation and exploration throughout the iteration process.The SSOM allows for local exploration around a single solution,improving solution quality and eliminating inferior solutions.The WPES enables comprehensive exploration of the solution space,avoiding the problem of getting trapped in local optima.The algo-rithm is evaluated by comparing it with 10 other competitive algorithms on various PV models.The results demonstrate that RSWTLBO consistently achieves the lowest Root Mean Square Errors on single diode models,double diode models,and PV module models.It also exhibits robust performance under varying irradiation and temperature conditions.The study concludes that RSWTLBO is a practical and effective algorithm for identifying unknown parameters in PV models.
基金approved by the Institutional Review Board of the Future Medical Research Centre Ethical Committee(Approval No.TGE02100-02).
文摘BACKGROUND Esophageal variceal bleeding is a severe complication associated with liver cirrhosis and typically necessitates endoscopic hemostasis.The current standard treatment is endoscopic variceal ligation(EVL),and Western guidelines recom-mend antibiotic prophylaxis following hemostasis.However,given the impro-vements in prognosis for variceal bleeding due to advancements in the management of bleeding and treatments of liver cirrhosis and the global concerns regarding the emergence of multidrug-resistant bacteria,there is a need to reassess the use of routine antibiotic prophylaxis after hemostasis.AIM To evaluate the effectiveness of antibiotic prophylaxis in patients treated for EVL.METHODS We conducted a 13-year observational study using the Tokushukai medical database across 46 hospitals.Patients were divided into the prophylaxis group(received antibiotics on admission or the next day)and the non-prophylaxis group(did not receive antibiotics within one day of admission).The primary outcome was composed of 6-wk mortality,4-wk rebleeding,and 4-wk spontaneous bacterial peritonitis(SBP).The secondary outcomes were each individual result and in-hospital mortality.A logistic regression with inverse probability of treatment weighting was used.A subgroup analysis was conducted based on the Child-Pugh classification to determine its influence on the primary outcome measures,while sensitivity analyses for antibiotic type and duration were also performed.RESULTS Among 980 patients,790 were included(prophylaxis:232,non-prophylaxis:558).Most patients were males under the age of 65 years with a median Child-Pugh score of 8.The composite primary outcomes occurred in 11.2%of patients in the prophylaxis group and 9.5%in the non-prophylaxis group.No significant differences in outcomes were observed between the groups(adjusted odds ratio,1.11;95%confidence interval,0.61-1.99;P=0.74).Individual outcomes such as 6-wk mortality,4-wk rebleeding,4-wk onset of SBP,and in-hospital mortality were not significantly different between the groups.The primary outcome did not differ between the Child-Pugh subgroups.Similar results were observed in the sensitivity analyses.CONCLUSION No significant benefit to antibiotic prophylaxis for esophageal variceal bleeding treated with EVL was detected in this study.Global reassessment of routine antibiotic prophylaxis is imperative.
基金supported by the National Natural Science Foundation of China(Grant No.12171450).
文摘This paper proposes a novel method for estimating the sparse inverse covariance matrixfor longitudinal data with informative dropouts. Based on the modified Cholesky decomposition,the sparse inverse covariance matrix is modelled by the autoregressive regression model,which guarantees the positive definiteness of the covariance matrix. To account for the informativedropouts, we then propose a penalized estimating equation method using the inverse probabilityweighting approach. The informative dropout propensity parameters are estimated by the generalizedmethod of moments. The asymptotic properties are investigated for the resulting estimators.Finally, we illustrate the effectiveness and feasibility of the proposed method through Monte Carlosimulations and a practical application.
基金supported by grants through funding from the National Science and Technology Council(MOST 111-2314-B-037-070-MY3,NSTC 112-2314-B-037-090,NSTC 112-2314-B-037-050-MY3)the Ministry of Health and Welfare(12D1-IVMOHW02)and funded by the Health and Welfare Surcharge of on Tobacco Products,and the Kaohsiung Medical University Hospital(KMUH112-2R37,KMUH112-2R38,KMUH112-2R39,KMUH112-2M27,KMUH112-2M28,KMUH112-2M29,KMUH-SH11207)Kaohsiung Medical University Research Center Grant(KMU-TC112A04).
文摘Abstract:Background:The pTNM staging system is widely recognized as the most effective prognostic indicator for cancer.The latest update of this staging system introduced a new pathological staging system(ypTNM)for patients receiving neoadjuvant chemoradiotherapy(NACRT).However,whether the prognostic value of the ypTNM staging system for rectal cancer is similar to that of the pTNM staging system remains unclear.This study was conducted to compare the ypTNM and pTNM staging systems in terms of their prognostic value for patients with nonmetastatic rectal cancer undergoing proctectomy.Material and Methods:This study was conducted at a large teaching hospital.Between January 2014 and December 2022,542 patients with rectal cancer were analyzed(median follow-up period,60 months;range,6–105 months).Of them,258 and 284 were included in the pTNM and ypTNM groups,respectively.Inverse probability of treatment weighting(IPTW)was performed to account for the effects of confounders.Cox proportional-hazards regression was performed for the between-group comparison of overall survival(OS).Results:The crude model revealed that OS was similar between the two groups(p=0.607).After performing IPTW,we found that patients with the same ypTNM-and pTNM-classified stages had similar overall survival(hazard ratio=1.15;95%CI=0.76–1.73;p=0.5074).Conclusions:For patients with rectal cancer who have received preoperative NACRT,the prognostic value of ypTNM staging appears to be similar to that of pTNM staging,mostly because of the downstaging effect of neoadjuvant chemoradiotherapy。
基金supported by the National Natural Science Foundation of China (70871117 70571086)the Development Foundation of Dalian Naval Academy
文摘The function of the air target threat evaluation （TE） is the foundation for weapons allocation and senor resources management within the surface air defense. The multi-attribute evaluation methodology is utilized to address the issue of the TE in which the tactic features of the detected target are treated as evaluation attributes. Meanwhile, the intuitionistic fuzzy set （IFS） is employed to deal with information uncertainty in the TE process. Furthermore, on the basis of the entropy weight and inclusion-comparison probability, a hybrid TE method is developed. In order to accommodate the demands of naturalistic decision making, the proposed method allows air defense commanders to express their intuitive opinions besides incorporating into the threat features of the detected target. An illustrative example is provided to indicate the feasibility and advantage of the proposed method.
基金supported by the National Key R&D Program of China,Grant No.2018YFA0306703 and J2019-V-0001-0092.
文摘Estimating the intention of space objects plays an important role in air-craft design,aviation safety,military and otherfields,and is an important refer-ence basis for air situation analysis and command decision-making.This paper studies an intention estimation method based on fuzzy theory,combining prob-ability to calculate the intention between two objects.This method takes a space object as the origin of coordinates,observes the target’s distance,speed,relative heading angle,altitude difference,steering trend and etc.,then introduces the spe-cific calculation methods of these parameters.Through calculation,values are input into the fuzzy inference model,andfinally the action intention of the target is obtained through the fuzzy rule table and historical weighted probability.Ver-ified by simulation experiment,the target intention inferred by this method is roughly the same as the actual behavior of the target,which proves that the meth-od for identifying the target intention is effective.
文摘In this article, to improve the doubly robust estimator, the nonlinear regression models with missing responses are studied. Based on the covariate balancing propensity score (CBPS), estimators for the regression coefficients and the population mean are obtained. It is proved that the proposed estimators are asymptotically normal. In simulation studies, the proposed estimators show improved performance relative to usual augmented inverse probability weighted estimators.
基金supported by the Fundamental Research Funds for the Central Universities(17CX02035A)supported by NNSF of China(11601197,11461029,61563018)+2 种基金China Postdoctoral Science Foundation funded project(2016M600511,2017T100475)NSF of Jiangxi Province(20171ACB21030,20161BAB201024,20161ACB200009)the Key Science Fund Project of Jiangxi provincial education department(GJJ150439)
文摘It is known that conditional independence is a quite basic assumption in many fields of statistics. How to test its validity is of great importance and has been extensively studied by the literature. Nevertheless, all of the existing methods focus on the case that data are fully observed, but none of them seems having taken into account of the scenario when missing data are present. Motivated by this, this paper develops two testing statistics to handle such a situation relying on the idea of inverse probability weighted and augmented inverse probability weighted techniques. The asymptotic distributions of the proposed statistics are also derived under the null hypothesis. The simulation studies indicate that both testing statistics perform well in terms of size and power.
基金reviewed and approved by the Institutional Review Board I&II of Taichung Veterans General Hospital(Approval No.TCVGH-IRB No.CE22408B).
文摘BACKGROUND Right-sided ligamentum teres(RSLT)is often associated with portal venous anomalies(PVA)and is regarded as a concerning feature for hepatobiliary intervention.Most studies consider RSLT to be one of the causes of left-sided gallbladder(LGB),leading to the hypothesis that LGB must always be present with RSLT.However,some cases have shown that right-sided gallbladder(RGB)can also be present in livers with RSLT.AIM To highlight the rare variation that RSLT may not come with LGB and to determine whether ligamentum teres(LT)or gallbladder location is reliable to predict PVA.METHODS This study retrospectively assessed 8552 contrast-enhanced abdominal computed tomography examinations from 2018 to 2021[4483 men,4069 women;mean age,59.5±16.2(SD)years].We defined the surrogate outcome as major PVAs.The cases were divided into 4 subgroups according to gallbladder and LT locations.On one hand,we analyzed PVA prevalence by LT locations using gallbladder location as a controlled variable(n=36).On the other hand,we controlled LT location and computed PVA prevalence by gallbladder locations(n=34).Finally,we investigated LT location as an independent factor of PVA by using propensity score matching(PSM)and inverse probability of treatment weighting(IPTW).RESULTS We found 9 cases of RSLT present with RGB.Among the LGB cases,RSLT is associated with significantly higher PVA prevalence than typical LT[80.0%vs 18.2%,P=0.001;OR=18,95%confidence interval(CI):2.92-110.96].When RSLT is present,we found no statistically significant difference in PVA prevalence for RGB and LGB cases(88.9%vs 80.0%,P>0.99).Both PSM and IPTW yielded balanced cohorts in demographics and gallbladder locations.The RSLT group had a significantly higher PVA prevalence after adjusted by PSM(77.3%vs 4.5%,P<0.001;OR=16.27,95%CI:2.25-117.53)and IPTW(82.5%vs 4.7%,P<0.001).CONCLUSION RSLT doesn't consistently coexist with LGB.RSLT can predict PVA independently while the gallbladder location does not serve as a sufficient predictor.
文摘<strong>Background:</strong> Acute Myeloid leukemia (AML) is the most prominent acute leukemia in adults. In the United States, we experience over 20,000 cases per year. Over the past decade, improvements in the diagnosis of subtypes of AML and advances in therapeutic approaches have improved the outlook for patients with AML. However, despite these advancements, the survival rate among patients who are less than 65 years of age is only 40 percent. <strong>Purpose:</strong> The purpose of the paper is to study if there exists any significant difference in the survival probabilities of male and female AML patients. Also, we want to investigate if there is any parametric probability distribution that best fits the male and female patient survival and compare the survival probabilities with the non-parametric Kaplan-Meier (KM) method. <strong>Methods:</strong> We used both parametric and non-parametric statistical methods to perform the survival analysis to assess the survival probabilities of 2015 patients diagnosed with AML.<strong> Results:</strong> We found evidence of a statistically significant difference between the mean survival time of male and female patients diagnosed with AML. We performed parametric survival analysis and found a Generalized Extreme Value (GEV) distribution best fitting the data of the survival time for male and female patients. We then estimated the survival probabilities and compared them with the frequently used non-parametric Kaplan-Meier (KM) survival method. <strong>Conclusion:</strong> The comparison between the survival probability estimates of the two methods revealed a better survival probability estimate by the parametric method than the Kaplan-Meier. We also compared the median survival time of male and female patients individually with descriptive, parametric, and non-parametric methods of analysis. The parametric survival analysis is more robust and efficient because it is based on a well-defined parametric probabilistic distribution, hence preferred over the non-parametric Kaplan-Meier estimate. This study offers therapeutic significance for further enhancement to treat patients with Acute Myeloid Leukemia.
基金the National Natural Science Foundation of China(No.72203249)Peng acknowledges financial support from the National Natural Science Foundation of China(No.71903208,72273160).
文摘Under probability weighting,entrepreneurs with skewness preference tend to seek rightskewed and avoid left-skewed risks.We show that Chinese firms managed by CEOs with professional epidemic experience,i.e.,who previously experienced the outbreak of SARS during their tenure as high level executives,have a lower stock price crash risk measured by the negative skewness of stock prices in subsequent periods.In particular,those firms intentionally avoid stock price crashes by adopting more conservative strategies in decisionmaking.Overall,we provide the first evidence on the unintended effect of entrepreneurs'subjective judgments of the probabilities of disease outbreaks on financial market stability.These have long-term implications for the financial system.
基金supported by Chongqing‘Direct Ph.D.Express’Research Project(CSTB2022BSXM-JCX0017)Chongqing Natural Science Foundation General Project(CSTB2022NSCQ-MSX0204).
文摘Background:Laparoscopic resection(LR)of perihilar cholangiocarcinoma(pCCA)is still in the exploratory stage due to its exacting technical requirements,and its feasibility remains controversial.The objective of this study was to compare the short-and long-term outcomes of LR and open resection(OR)of pCCA.Methods:This study analyzed the data of pCCA patients who underwent LR or OR from January 2012 to January 2020 at Southwest Hospital.Inverse probability of treatment weighting(IPTW)and propensity score matching(PSM)were used to balance the baseline characteristics between the LR and OR groups.The short-and long-term outcomes were compared between the LR and OR groups.Results:Forty-five patients in the LR group and 243 in the OR group were analyzed.After IPTW and PSM,the amount of intraoperative blood loss,incidence of surgical site infections(SSIs),length of stay(LOS),and number of perioperative blood transfusions(PBTs)were significantly lower in the LR group than in the OR group(after IPTW:P<0.001,P=0.009,P=0.01,P<0.001 respectively;after PSM:P<0.001,P=0.003,P=0.03,P=0.04 respectively).Only after IPTW was the 30-day mortality rate significantly lower in the LR group than in the OR group(P=0.005).There was no significant difference in overall survival(OS)or recurrence-free survival(RFS)between the two groups after IPTW or PSM.Conclusions:LR of pCCA is an achievable procedure whose long-term outcomes are similar to those of OR,and LR outperforms OR in short-term outcomes such as intraoperative blood loss,SSI,LOS,30-day mortality,and PBTs.It is believed that it is safe and feasible to treat pCCA with LR after rigorous patient selection.
基金the National Institute for Health Research(grant number NIHR200134)using Official Development Assistance(ODA)funding.
文摘Attrition is a common challenge in statistical analysis for longitudinal or multi-stage cross-sectional studies.While strategies to reduce attrition should ideally be implemented during the study design phase,they remain common in real-world research,necessitating statistical methods to address them.Tra-ditional approaches like multiple imputation(MI)and inverse probability weighting(IPW)rely on the assumption that data is missing at random(MAR),which is not always plausible.Recent developments in machine learn-ing(ML)based methods offer promising alternatives because of their ability to capture complex patterns in data and handle non-linear relationships more effectively.This study examines four ML-based imputation methods to ac-count for attrition and compares them with conventional MI and IPW in a two-stage epilepsy population-based prevalence survey involving 56,425 par-ticipants.Simulated attrition levels from 5%to 50%were applied following the MAR mechanism to assess the performance of the different methods.This was replicated 100 times using different random seeds.Results showed that bias increased with an increase in attrition levels.Complete case analysis had the largest bias in all scenarios.k-nearest neighbor(KNN)and sequential KNN(sKNN)performed similarly to MI under MAR but exhibited less bias than MI and IPW when data were MNAR.While IPW performed similarly to MI under MAR,it had greater bias under MNAR.Both missForest and the MI implemented using random forest were outperformed by sKNN and KNN.We have demonstrated that even a small attrition proportion of 5%can sig-nificantly bias estimates if not properly addressed.While MI is still the most preferred for missing data assuming MAR,ML methods,particularly sKNN and KNN demonstrated potential for addressing attrition when data are MNAR.Choosing the appropriate method to address missing data should be preceded by an evaluation of different available methods that could be suitable for the data being analysed.Future research should explore ML methods in various study designs and consider integrating ML into the very robust MI framework to improve prediction accuracy for missing data due to attrition.
基金support from the NSFC(Grant No.11471276,11971409)The Hong Kong RGC(GRF Grant No.15202817,15202421,15204622 and 15203423)+1 种基金the PolyU-SDU Joint Research Center on Financial Mathematics,the CAS AMSS-PolyU Joint Laboratory of Applied Mathematics,the Research Centre for Quantitative Finance(1-CE03)internal grants from The Hong Kong Polytechnic University.
文摘This papcr investigates a Parcto optimal insurancc contract design problcm within a behavioral finance framework.In this context,the insured evaluates contracts using the rank-dependent utility(RDU,for short)theory,while the insurer applies the expected value premium principle.The analysis incorporates the incentive compatibility constraint,ensuring that the contracts,called moral-hazard-free,are free from the moral hazard issues identified in Bernard et al.[4].Initially,the problem is formulated as a nonconcave maximization problem involving Choquet expectation.It is then transformed into a quantile optimization problem and addrcssed using thc calculus of variations mcthod.The optimal contracts are characterized by a double-obstacle ordinary differential equation for a semi-linear second-order elliptic operator with nonlocal boundary conditions,which seems new in the financial economics literature.We present a straightforward numerical scheme and a numerical example to compute the optimal contracts.Let and mo represent the relative safety loading and the mass of the potential loss at O,respectively.We discover that every moral-hazard-free contract is optimal for infinitely many RDU-insured individuals if 0<θ<m_(0)/1-m_(0).Conversely,certain contracts,such as the full coverage contract,are never optimal for any RDU-insured individual ifθ>m_(0)/1-m_(0)Additionally,we derive all the Pareto optimal contracts when either the compensation or the retention violates the monotonicity constraint.
文摘Background:Burns resulting from assaults account for considerable morbidity and mortality among patients with burn injuries around the world.However,it is still unclear whether unfavorable clinical outcomes are associated primarily with the severity of the injuries.To elucidate the direct relationship between burns resulting from assaults and mortality and/or length of hospital stays,we performed this study with the hypothesis that burns from assault would be independently associated with fewer hospital-free days than would burns from other causes,regardless of the severity of burn injuries.Methods:We conducted a retrospective cohort study,using a city-wide burn registry(1996–2017)accounting for 14 burn centers in Tokyo,Japan.Patients who arrived within 24 hours after injury were included,and those with self-inflicted burn injuries were excluded.Patients were divided into two groups according to mechanism of burns(assault vs.accident),and the number of hospitalfree days until day 30 after injury(a composite of in-hospital death and hospital length of stay)was compared between the groups.To estimate the probability that an injury would be classified as an assault,we calculated propensity scores,using multivariate logistic regression analyses adjusted for known outcome predictors.We also performed an inverse probability weighting(IPW)analysis to compare adjusted numbers of hospital-free days.Results:Of 7419 patients in the registry with burn injuries during the study period,5119 patients were included in this study.Of these,113(2.2%)were injured as a result of assault;they had significantly fewer hospital-free days than did those with burns caused by accident(18[27]vs.24[20]days;coefficient=−3.4[−5.5 to−1.3]days;p=0.001).IPW analyses similarly revealed the independent association between assault burn injury and fewer hospital-free days(adjusted coefficient=−0.6[−1.0 to−0.1]days;p=0.009).Conclusions:Burn from assault was independently associated with fewer hospital-free days,regardless of the severity of burn injuries.The pathophysiological mechanism underlying the relationship should be further studied in a prospective observational study.
基金partially supported by the National Natural Science Foundation of China(No.81872719)the National Bureau of Statistics Foundation Project(No.2018LY79)+6 种基金the Natural Science Foundation of Shandong Province(No.2019MH034)the Poverty Alleviation Fund project of Weifang Medical University(No.FP1801001)partially supported by the National Natural Science Foundation of China(No.81803337)the Shandong Provincial Youth Innovation Team Development Plan of Colleges and Universities(No.2019-6-156,Lu-Jiao)the Shandong Provincial Government Fund for Overseas Study(No.27,2019,Lu-Jiao)the Shandong Science and Technology Development Plan Project(No.2015 WS0067)the Weifang Medical University Doctoral Foundation Project(No.2017BSQD51).
文摘Objective:This study conducted inverse probability of treatment weighting(IPTW)survival analysis to examine survival in pancreatic adenocarcinoma patients.Methods:In this population-based study,data from the Surveillance,Epidemiology,and End Results program of the United States were analyzed to identify patients diagnosed with adenocarcinoma of the pancreas 2004 to 2014.Differences in survival rates were examined among patients who underwent pancreatectomy alone,radiotherapy alone,and those who had pancreatectomy plus adjuvant radiotherapy.Kaplan-Meier estimates and Cox proportional hazards models with the IPTW were performed to determine the effect of different treatments on overall and cancer-specific survival.This study was approved by the Ethics Review Board of Weifang Medical University.Results:A total of 8191 patients were included,with 3409 taking pancreatectomy only,2865 taking radiotherapy only,and 1917 taking pancreatectomy plus adjuvant radiotherapy.Patients who received surgery plus adjuvant radiotherapy had statistically a higher survival rate than those who received the other 2 treatments.Survival analysis with the IPTW for the 3 different groups showed that the difference in median overall survival time among these patient groups was significant.Conclusion:Using IPTW survival analysis,the present study shows that surgery with adjuvant radiotherapy is significantly associated with improved overall and cancer-specific survival among patients with pancreatic adenocarcinoma.
基金supported by theNational Natural Science Foundation of China(No.11771032 and No.11971045)Natural Science Foundation of Beijing(No.1202001)+1 种基金supported by the National Natural Science Foundation of China(No.11871001,No.12131006 and No.11971001)the Fundamental Research Funds for the Central Universities(2019NTSS18).
文摘Doubly robust(DR)methods that employ both the propensity score and outcome models are widely used to estimate the causal effect of a treatment and generally outperform those methods only using the propensity score or the outcome model.However,without appropriately chosen the working models,DR estimators may substantially lose efficiency.In this paper,based on the augmented inverse probability weighting procedure,we derive a new estimating equation for the causal effect by the strategy of combining estimating equations.The resulting estimator by solving the new estimating equation retains doubly robust and can improve the efficiency under the misspecification of conditional mean working model.We further show the large sample properties of the proposed estimator under some regularity conditions.Through simulation experiments and a real data analysis,we illustrate that the proposed method is competitive with its competitors,which is in line with those implied by the asymptotic theory.
基金supported by the National Key Research and Development Plan(No.2016YFC0800100)the NSFC of China(No.11671374,71771203,71631006).
文摘We mainly focus on regression estimation in a longitudinal study with nonignorable intermittent nonresponse and dropout.To handle the identifiability issue,we take a time-independent covariate as nonresponse instrument which is independent of nonresponse propensity conditioned on other covariates and responses to ensure the identifiability of nonresponse propensity.The nonresponse propensity is assumed to be a parametric model,and the corresponding parameters are estimated by using the generalized method of moments approach.Then the marginal response means are estimated by inverse probability weighting method.Furthermore,to improve the robustness of estimators,we derive an augmented inverse probability weighting estimator which is shown to be consistent and asymptotically normally distributed.Simulation studies and a real-data analysis show that the proposed approach yields highly efficient estimators.
文摘Background:Metabolic dysfunction-associated fatty liver disease(MAFLD)is a common liver disease,the risk of which can be increased by poor diet.The objective of this study was to evaluate the associations between food items and MAFLD,and to propose reasonable dietary recommendations for the prevention of MAFLD.Methods:Physical examination data were collected from April 2015 through August 2017 at Nanping First Hospital(n=3,563).Dietary intakes were assessed using a semi-quantitative food frequency questionnaire.The association between food intake and the risk of MAFLD was assessed by using the inverse probability weighted propensity score.Results:Beverages(soft drinks and sugar-sweetened beverages)and instant noodles were positively associated with MAFLD risk,adjusting for smoking,drinking,tea intake,and weekly hours of physical activity[adjusted odds ratio(ORadjusted):1.568;P=0.044;ORadjusted:4.363;P=0.001].Milk,tubers,and vegetables were negatively associated with MAFLD risk(ORadjusted:0.912;P=0.002;ORadjusted:0.633;P=0.007;ORadjusted:0.962;P=0.028).In subgroup analysis,the results showed that women[odds ratio(OR):0.341,95%confidence interval(CI):0.172–0.676]had a significantly lower risk of MAFLD through consuming more tubers than men(OR:0.732,95%CI:0.564–0.951).Conclusions:These findings suggest that reducing consumption of beverages(soft drinks and sugar-sweetened beverages)and instant noodles,and consuming more milk,vegetables,and tubers may reduce the risk of MAFLD.
