Can propensity score matching replace randomized controlled trials?

Randomized controlled trials(RCTs)have long been recognized as the gold standard for establishing causal relationships in clinical research.Despite that,various limitations of RCTs prevent its widespread implementation,ranging from the ethicality of withholding potentially-lifesaving treatment from a group to relatively poor external validity due to stringent inclusion criteria,amongst others.However,with the introduction of propensity score matching(PSM)as a retrospective statistical tool,new frontiers in establishing causation in clinical research were opened up.PSM predicts treatment effects using observational data from existing sources such as registries or electronic health records,to create a matched sample of participants who received or did not receive the intervention based on their propensity scores,which takes into account characteristics such as age,gender and comorbidities.Given its retrospective nature and its use of observational data from existing sources,PSM circumvents the aforementioned ethical issues faced by RCTs.Majority of RCTs exclude elderly,pregnant women and young children;thus,evidence of therapy efficacy is rarely proven by robust clinical research for this population.On the other hand,by matching study patient characteristics to that of the population of interest,including the elderly,pregnant women and young children,PSM allows for generalization of results to the wider population and hence greatly increases the external validity.Instead of replacing RCTs with PSM,the synergistic integration of PSM into RCTs stands to provide better research outcomes with both methods complementing each other.For example,in an RCT investigating the impact of mannitol on outcomes among participants of the Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial,the baseline characteristics of comorbidities and current medications between treatment and control arms were significantly different despite the randomization protocol.Therefore,PSM was incorporated in its analysis to create samples from the treatment and control arms that were matched in terms of these baseline characteristics,thus providing a fairer comparison for the impact of mannitol.This literature review reports the applications,advantages,and considerations of using PSM with RCTs,illustrating its utility in refining randomization,improving external validity,and accounting for non-compliance to protocol.Future research should consider integrating the use of PSM in RCTs to better generalize outcomes to target populations for clinical practice and thereby benefit a wider range of patients,while maintaining the robustness of randomization offered by RCTs.

Robotic vs laparoscopic abdominoperineal resection for rectal cancer:A propensity score matching cohort study and metaanalysis

BACKGROUND Robotic surgery(RS)is gaining popularity;however,evidence for abdominoperineal resection(APR)of rectal cancer(RC)is scarce.AIM To compare the efficacy of RS and laparoscopic surgery(LS)in APR for RC.METHODS We retrospectively identified patients with RC who underwent APR by RS or LS from April 2016 to June 2022.Data regarding short-term surgical outcomes were compared between the two groups.To reduce the effect of potential confounding factors,propensity score matching was used,with a 1:1 ratio between the RS and LS groups.A meta-analysis of seven trials was performed to compare the efficacy of robotic and laparoscopic APR for RC surgery.RESULTS Of 133 patients,after propensity score matching,there were 42 patients in each group.The postoperative complication rate was significantly lower in the RS group(17/42,40.5%)than in the LS group(27/42,64.3%)(P=0.029).There wasno significant difference in operative time(P=0.564),intraoperative transfusion(P=0.314),reoperation rate(P=0.314),lymph nodes harvested(P=0.309),or circumferential resection margin(CRM)positive rate(P=0.314)between the two groups.The meta-analysis showed patients in the RS group had fewer positive CRMs(P=0.04),lesser estimated blood loss(P<0.00001),shorter postoperative hospital stays(P=0.02),and fewer postoperative complications(P=0.002)than patients in the LS group.CONCLUSION Our study shows that RS is a safe and effective approach for APR in RC and offers better short-term outcomes than LS.

Clinical effect of laparoscopic radical resection of colorectal cancer based on propensity score matching

BACKGROUND The incidence of colorectal cancer(CRC)is increasing annually.Laparoscopic radical resection of CRC is a minimally invasive procedure preferred in clinical practice.AIM To investigate the clinical effect of laparoscopic radical resection of CRC on the basis of propensity score matching(PSM).METHODS The clinical data of 100 patients who received inpatient treatment for CRC at Changde Hospital,Xiangya School of Medicine,Central South University(The First People’s Hospital of Changde City)were analyzed retrospectively.The control group included patients who underwent open surgery(n=43),and those who underwent laparoscopic surgery formed the observation group(n=57).The baseline information of both groups was equipoised using 1×1 PSM.Differences in the perioperative parameters,inflammatory response,immune function,degree of pain,and physical status between the groups were analyzed.RESULTS Thirty patients from both groups were successfully matched.After PSM,baseline data showed no statistically significant differences between the groups:(1)Periop-erative parameters:The observation group had a longer surgery time,less intra-operative blood loss,earlier first ambulation and first anal exhaust times,and shorter gastric tube indwelling time than the control group;(2)Inflammatory response:24 h after surgery,the levels of interleukin-6(IL-6),C-reactive protein(CRP),and tumor necrosis factor-α(TNF-α)between groups were higher than preoperatively.IL-6,CRP,and TNF-αlevels in the observation group were lower than in the control group;(3)Immune function:At 24 h after surgery,counts of CD4-positive T-lymphocytes(CD4+)and CD4+/CD8-positive T-lymphocytes(CD8+)in both groups were lower than those before surgery,whereas CD8+was higher than that before surgery.At 24 h after surgery,both CD4+counts and CD4+/CD8+in the observation group were higher than those in the control group,whereas CD8+counts were lower;(4)Degree of pain:The visual analog scale scores in the observation group were lower than those in the control group at 24 and 72 h after surgery;and(5)Physical status:One month after surgery,the Karnofsky performance score in the observation group was higher than that in the control group.CONCLUSION Laparoscopic radical resection of CRC has significant benefits,such as reducing postoperative pain and postoperative inflammatory response,avoiding excessive immune inhibition,and contributing to postoperative recovery.

Heparin-binding protein as a predictor of mortality in patients with diabetes mellitus and community-acquired pneumonia in intensive care unit:a propensity score matched study

BACKGROUND:Patients with diabetes mellitus(DM)are vulnerable to community-acquired pneumonia(CAP),which have a high mortality rate.We aimed to investigate the value of heparin-binding protein(HBP)as a prognostic marker of mortality in patients with DM and CAP.METHODS:This retrospective study included CAP patients who were tested for HBP at intensive care unit(ICU)admission from January 2019 to April 2020.Patients were allocated to the DM or non-DM group and paired with propensity score matching.Baseline characteristics and clinical outcomes up to 90 days were evaluated.The primary outcome was the 10-day mortality.Receiver operating characteristic(ROC)curves,Kaplan-Meier analysis,and Cox regression were used for statistical analysis.RESULTS:Among 152 enrolled patients,60 pairs were successfully matched.There was no significant difference in 10-day mortality,while more patients in the DM group died within 28 d(P=0.024)and 90 d(P=0.008).In the DM group,HBP levels at ICU admission were higher in 10-day non-survivors than in 10-day survivors(median 182.21[IQR:55.43-300]ng/ml vs.median 66.40[IQR:34.13-107.85]ng/mL,P=0.019),and HBP levels could predict the 10-day mortality with an area under the ROC curve of 0.747.The cut-off value,sensitivity,and specificity were 160.6 ng/mL,66.7%,and 90.2%,respectively.Multivariate Cox regression analysis indicated that HBP was an independent prognostic factor for 10-day(HR 7.196,95%CI:1.596-32.455,P=0.01),28-day(HR 4.381,95%CI:1.449-13.245,P=0.009),and 90-day mortality(HR 4.581,95%CI:1.637-12.819,P=0.004)in patients with DM.CONCLUSION:Plasma HBP at ICU admission was associated with the 10-day,28-day,and 90-day mortality,and might be a prognostic factor in patients with DM and CAP.

Endovenous laser treatment vs conventional surgery for great saphenous vein varicosities: A propensity score matching analysis

BACKGROUND Varicosis is a common venous condition,which is typically treated surgically.However,selection of the optimal surgical approach can be challenging.Previous studies comparing endovenous laser treatment(EVLT)and conventional surgery were retrospective and observational in nature and the results may therefore have been influenced by selection bias and the presence of other confounding factors.In this study,we used propensity score matching to reduce selection bias when comparing EVLT and conventional surgery for the treatment of varicose great saphenous veins.METHODS We retrospectively reviewed the records of 1063 patients treated for primary varicosis of the great saphenous vein at the Second Affiliated Hospital of Xuzhou Medical University between January 2009 and December 2019.Among them,56 patients were excluded owing to additional small saphenous varicose vein involvement,81 owing to recurring varicose veins,83 owing to complicated varicose veins(CEAP clinical classification C5-C6),and 6 owing to perioperative phlebitis.Finally,772 patients were enrolled in this study.Standard demographic and clinicopathological data were collected from the medical records of the patients.For propensity score matching,522 patients(261 who underwent EVLT and 261 who underwent conventional surgery)were randomly matched 1:1 by age,sex,onset time,smoking status,presence of diabetes,family history,stress therapy,C class,and the affected leg.RESULTS Of the 772 patients included in the study,467 underwent EVLT and 305 underwent conventional surgery.There were significant differences in age,onset time,smoking and diabetes status,and family history between the two groups.Following propensity score matching,no significant differences in patients’characteristics remained between the two groups.ELVT was associated with a shorter operation time and hospital stay than conventional surgery,both before and after propensity score matching.There were no differences in complications between the two groups after propensity score matching.Patients who underwent EVLT had a higher recurrence rate during the two-year follow-up period than those who underwent conventional surgery(33.33%vs 21.46%,χ^(2)=11.506,P=0.001),and a greater percentage of patients who underwent EVLT experienced pain one week after the procedure(39.85%vs 19.54%,P=0.000).CONCLUSION EVLT may not always be the best option for the treatment of great saphenous vein varicosis.

Does gastric stump cancer really differ from primary proximal gastric cancer? A multicentre, propensity score matching-used, retrospective cohort study

BACKGROUND Although the location of proximal cancer of the remnant stomach is the same as that of primary proximal cancer of the stomach,its clinical characteristics and prognosis are still controversial.AIM To evaluate the clinicopathological features and prognosis factors of gastric stump cancer(GSC)and primary proximal gastric cancer(PGC).METHODS From January,2005 to December,2016,178 patients with GSC and 957 cases with PGC who received surgical treatment were enrolled.Patients in both groups underwent 1:1 propensity score matching analysis,and both clinical and pathological data were systematically collected for statistical purposes.Quality of RESULTS One hundred and fifty-two pairs were successfully matched after propensity score matching analysis.Of the 15 demographic and pathological variables collected,the analysis further revealed that the number of lymph nodes and positive lymph nodes were different prognostic and clinicopathological factors between PGC and GSC.Univariate and multivariate analyses showed that gender,differentiation degree and tumor-node-metastasis stage were independent risk factors for patients with GSC.Gender,vascular invasion,differentiation degree,depth of infiltration,positive lymph nodes,and tumor-node-metastasis stage were independent risk factors for patients with PGC.The 5-year overall survival and cancer-specific survival of patients with GSC were significantly lower than those in the PGC group,the scores for overall quality of life in the GSC-malignant group were lower than the GSC-benign,and the differences were statistically significant.CONCLUSION The differences in clinicopathological characteristics between GSC and PGC were clarified,and PGC had a better prognosis than GSC.

Effects of Continuous Non-Invasive Blood Pressure Monitoring on Intraoperative Hemodynamics and Postoperative Myocardial Injury in Craniotomy:Comparison Between Groups Based on Self-Control and Propensity Score Matching

Objective:To explore the effect of continuous non-invasive blood pressure monitoring on intraoperative hemodynamics and postoperative myocardial injury in craniotomy.Methods:120 cases of elective craniotomy were divided into the self-control group(continuous non-invasive blood pressure monitoring and intermittent cuff non-invasive blood pressure monitoring,CNAP group)and propensity score matching group(only intermittent cuff non-invasive blood pressure measurement in previous craniotomy,PSM group);Goal-directed hemodynamic management in CNAP group included heart rate(HR),blood pressure(BP),stroke volume(SV),stroke variability(SVV),and systemic vascular resistance index(SVRI).The main index is to compare the troponin level within 72 hours after operation between the CNAP group and the PSM group;The secondary indicators are the comparison of the hemodynamic conditions between the CNAP group and the PSM at 10 specific time points.Results:The incidence of postoperative myocardial injury in the CNAP group was significantly lower than that in the PSM group(12%vs.30%,P=0.01);in the CNAP group hypotensive episodes(6 vs.3,P=0.01),positive balance of fluid therapy(700 vs.500 mL,P<0.001),more use of vasoactive drugs(29 vs.18,P=0.04),more stable hemodynamics medical status(P=0.03)were recorded.Conclusion:The hemodynamic management strategy based on continuous non-invasive blood pressure monitoring can reduce the incidence of myocardial injury after elective craniotomy and maintain a more stable hemodynamic state.

Robotic versus laparoscopic distal pancreatectomy for pancreatic ductal adenocarcinoma: A propensity score-matched analysis

Background: Minimally invasive surgery is becoming increasingly popular in the field of pancreatic surgery. However, there are few studies of robotic distal pancreatectomy(RDP) for pancreatic ductal adenocarcinoma(PDAC). This study aimed to investigate the efficacy and feasibility of RDP for PDAC. Methods: Patients who underwent RDP or laparoscopic distal pancreatectomy(LDP) for PDAC between January 2015 and September 2020 were reviewed. Propensity score matching analyses were performed. Results: Of the 335 patients included in the study, 24 underwent RDP and 311 underwent LDP. A total of 21 RDP patients were matched 1:1 with LDP patients. RDP was associated with longer operative time(209.7 vs. 163.2 min;P = 0.003), lower open conversion rate(0% vs. 4.8%;P < 0.001), higher cost(15 722 vs. 12 699 dollars;P = 0.003), and a higher rate of achievement of an R0 resection margin(90.5% vs. 61.9%;P = 0.042). However, postoperative pancreatic fistula grade B or C showed no significant intergroup difference(9.5% vs. 9.5%). The median disease-free survival(34.5 vs. 17.3 months;P = 0.588) and overall survival(37.7 vs. 21.9 months;P = 0.171) were comparable between the groups. Conclusions: RDP is associated with longer operative time, a higher cost of surgery, and a higher likelihood of achieving R0 margins than LDP.

Laparoscopic liver resection for hepatocellular carcinoma complicated with significant portal hypertension:A propensity score-matched survival analysis

Background: Significant portal hypertension(SPH) is a relative contraindication for patients with resectable hepatocellular carcinoma(HCC). However, increasing evidence indicates that liver resection is feasible for HCC patients with SPH. Methods: HCC patients with cirrhosis who underwent laparoscopic liver resection(LLR) in two centers from January 2013 to April 2018 were included. Surgical and survival outcomes were analyzed to explore potential prognostic factors. Propensity score matching(PSM) analysis was performed to minimize bias. Results: A total of 165 patients were divided into two groups based on the presence(SPH, n = 76) or absence(non-SPH, n = 89) of SPH. Patients in the SPH group had longer operative time, more blood loss, and more advanced TNM stage than patients in the non-SPH group( P < 0.05). However, there were no significant differences in the postoperative 90-day mortality rate( n = 0), overall postoperative complications(47.4% vs. 41.6%, P = 0.455), Clavien-Dindo classification( P = 0.347), conversion to open surgery(9.2% vs. 6.7%, P = 0.557), or length of hospitalization(16 vs. 15 days, P = 0.203) between the SPH and non-SPH groups before PSM. Similar results were obtained after PSM. The 1-, 3-, and 5-year overall survival(OS) and recurrence-free survival rates in the SPH group were not significantly different from those in the non-SPH group both before and after PSM(log-rank P > 0.05). After PSM, alpha-fetoprotein(AFP) ≥ 400 μg/L [hazard ratio(HR) = 4.71, 95% confidence interval(CI): 2.69-8.25], ascites(HR = 2.18, 95% CI: 1.30-3.66), American Society of Anesthesiologists(ASA) classification(Ⅲ vs. Ⅱ)(HR = 2.13, 95% CI: 1.11-4.07) and tumor diameter > 5 cm(HR = 3.91, 95% CI: 2.02-7.56) independently predicted worse OS. Conclusions: LLR for patients with HCC complicated with SPH appears feasible at the price of increasing operative time and blood loss. AFP, ascites, ASA classification and tumor diameter may predict the prognosis of HCC complicated with SPH after LLR.

Progress in hepatitis B virus-related acute-on-chronic liver failure treatment in China:A large,multicenter,retrospective cohort study using a propensity score matching analysis

Background:Hepatitis B virus-related acute-on-chronic liver failure(HBV-ACLF)has a high short-term mortality.However,the treatment progression for HBV-ACLF in China in the past decade has not been well characterized.The present study aimed to determine whether the HBV-ACLF treatment has significantly improved during the past decade.Methods:This study retrospectively compared short-term(28/56 days)survival rates of two different nationwide cohorts(cohort I:2008-2011 and cohort II:2012-2015).Eligible HBV-ACLF patients were enrolled retrospectively.Patients in the cohorts I and II were assigned either to the standard medical therapy(SMT)group(cohort I-SMT,cohort II-SMT)or artificial liver support system(ALSS)group(cohort IALSS,cohort II-ALSS).Propensity score matching analysis was conducted to eliminate baseline differences,and multivariate logistic regression analysis was used to explore the independent factors for 28-day survival.Results:Short-term(28/56 days)survival rates were significantly higher in the ALSS group than those in the SMT group(P<0.05)and were higher in the cohort II than those in the cohort I(P<0.001).After propensity score matching,short-term(28/56 days)survival rates were higher in the cohort II than those in the cohort I for both SMT(60.7%vs.53.0%,50.0%vs.39.8%,P<0.05)and ALSS(66.1%vs.56.5%,53.0%vs.44.4%,P<0.05)treatments.The 28-day survival rate was higher in patients treated with nucleos(t)ide analogs than in patients without such treatments(P=0.046).Multivariate logistic regression analysis revealed that ALSS(OR=0.962,95%CI:0.951-0.973,P=0.038),nucleos(t)ide analogs(OR=0.927,95%CI:0.871-0.983,P=0.046),old age(OR=1.028,95%CI:1.015-1.041,P<0.001),total bilirubin(OR=1.002,95%CI:1.001-1.003,P=0.004),INR(OR=1.569,95%CI:1.044-2.358,P<0.001),COSSH-ACLF grade(OR=2.683,95%CI:1.792-4.017,P<0.001),and albumin(OR=0.952,95%CI:0.924-0.982,P=0.002)were independent factors for 28-day mortality.Conclusions:The treatment for patients with HBV-ACLF has improved in the past decade.

Survival difference between EGFR Del19 and L858R mutant advanced non-small cell lung cancer patients receiving gefitinib:a propensity score matching analysis

Objective： Although superior clinical benefits of epidermal growth factor receptor （EGFR） tyrosine kinase inhibitors （TKIs） in the treatment of advanced non-small-cell lung cancer （NSCLC） had been reported, the survival difference between exon 19 deletion （Dell9） and exon 21 Leu858Arg substitution （L858R） remains controversial. The purpose of this study is to investigate the differences in progression-free survival （PFS） and overall survival （OS） between different EGFR mutant subtypes among advanced NSCLC patients receiving gefitinib. Methods： There were 204 advanced NSCLC patients with EGFR mutations treated with gefitinib were enrolled in this retrospective cohort study. Patients were divided into the EGFR Dell9 group and the L858R mutated group according to their mutant subtype. Propensity score matching （PSM） was conducted by using a nearest-neighbor algorithm （1：1） to adjust for demographical and clinical covariates. Survival curves were constructed with the Kaplan-Meier method and compared by using the log-rank test. Results： The PFS in Dell9 group was similar to that in the L858R group [before PSM 8.6 vs. 7.2 months, P=0.072; after PSM 7.3 vs. 7.2 months, P=0.155]. No differences were detected in OS between the L858R and the Dell9 group （before PSM 17.8 vs. 13.1 months, P=0.253; after PSM 16.9 vs. 13.1 months, P=0.339）. The Dell9 group was significantly younger compared with the L858R mutation group in age （P=0.015）. Conclusions： No significant difference was found in the PFS or OS between the Dell9 and L858R mutant NSCLC patients receiving gefitinib. The age gap might contribute to the survival differences between Dell9 and L858R groups. PSM is of important value to the elimination of potential bias.

Cholecystectomy is associated with higher risk of recurrence after microwave ablation of hepatocellular carcinoma:a propensity score matching analysis

Objective:To explore the association between cholecystectomy and the prognostic outcomes of patients with hepatocellular carcinoma(H CC)who underwent microwave ablation(MWA).Methods:Patients with HCC(«=921)who underwent MWA were included and divided into cholecystectomy(n=114)and non-cholecystectomy groups(n=807).After propensity score matching(PSM)at a 1:2 ratio,overall survival(OS)and disease-free survival(DFS)rates were analyzed to compare prognostic outcomes between the cholecystectomy(«=114)and non-cholecystectomy groups(n=228).Univariate and multivariate Cox analyses were performed to assess potential risk factors for OS and DFS.Major complications were also compared between the groups.Results:After matching,no significant differences between groups were observed in baseline characteristics.The 1-,3-,and 5-year OS rates were 96.5%,82.1%,and 67.1%in the cholecystectomy group,and 97.4%,85.2%,and 74.4%in the non-cholecystectomy group(P=0.396);the 1-,3-,and 5-year DFS rates were 58.4%,34.5%,and 26.6%in the cholecystectomy group,and 73.6%,44.7%,and 32.2%in the non-cholecystectomy group(P=0.026),respectively.The intrahepatic distant recurrence rate in the cholecystectomy group was significantly higher than that in the non-cholecystectomy group(P=0.026),and the local tumor recurrence and extrahepatic recurrence rates did not significantly differ between the groups(P=0.609 and P=0.879).Multivariate analysis revealed that cholecystectomy(HR=1.364,95%Cl 1.023-1.819,P=0.035),number of tumors(2 vs.1:HR=2.744,95%Cl 1.925-3.912,P<0.001;3 vs.1:HR=3.411,95%Cl 2.021-5.759,P<0.001),and y-GT levels(HR=1.003,95%Cl 1.000-1.006,P<0.024)were independent risk factors for DFS.The best y-GT level cut-off value for predicting median DFS was 39.6 U/L(area under the curve=0.600,P<0.05).A positive correlation was observed between cholecystectomy and y-GT level(r=0.108,95%Cl-0.001-0.214,P=0.047).Subgroup analysis showed that the DFS rates were significantly higher in the non-cholecystectomy group than the cholecystectomy group when Y-GT>39.6 U/L(i3=0.044).The 5-,10-,15-,20-,and 25-year recurrence rates from the time of cholecystectomy were 2.63%,21.93%,42.11%,58.77%,and 65.79%,respectively.A significant positive correlation was observed between cholecystectomy and the time from cholecystectomy to recurrence(r=0.205,95%Cl 0.016-0.379,P=0.029).There were no significant differences in complications between groups(P=0.685).Conclusions:Patients with HCC who underwent cholecystectomy were more likely to develop intrahepatic distant recurrence after MWA,an outcome probably associated with increased y-GT levels.Moreover,the recurrence rates increased with time.

Short-term and middle-term evaluation of laparoscopic hepatectomies compared with open hepatectomies: A propensity score matching analysis

AIM To compare short-term results between laparoscopic hepatectomy and open hepatectomy using a propensity score matching. METHODS A patient in the laparoscopic liver resection(LLR) groupwas randomly matched with another patient in the open liver resection(OLR) group using a 1:1 allocated ratio with the nearest estimated propensity score. Patients of the LLR group without matches were excluded. Matching criteria included age, gender, body mass index, American Society of Anesthesiologists score, potential co-morbidities, hepatopathies, size and number of nodules, preoperative chemotherapy, minor or major liver re-sections. Intraoperative and postoperative data were compared in both groups.RESULTS From January 2012 to January 2015, a total of 241 hepa-tectomies were consecutively performed, of which 169 in the OLR group(70.1%) and 72 in the LLR group(29.9%). The conversion rate was 9.7%(n = 7). The mortality rate was 4.2% in the OLR group and 0% in the LLR group. Prior to and after propensity score matching, there was a statistically significant difference favorable to the LLR group regarding shorter operative times(185 min vs 247.5 min; P = 0.002), less blood loss(100 m L vs 300 m L; P = 0.002), a shorter hospital stay(7 d vs 9 d; P = 0.004), and a significantly lower rate of medical complications(4.3% vs 26.4%; P < 0.001). CONCLUSION Laparoscopic liver resections seem to yield better short-term and mid-term results as compared to open hepatectomies and could well be considered a privileged approach and become the gold standard in carefully selected patients.

Laparoscopic vs open total gastrectomy for advanced gastric cancer following neoadjuvant therapy:A propensity score matching analysis

BACKGROUND Laparoscopic total gastrectomy(LTG)has drawn increasing attention over the years.Although LTG has shown surgical benefits compared to open TG(OTG)in early stage gastric cancer(GC),little is known about the surgical and oncological outcomes of LTG for advanced GC following neoadjuvant therapy(NAT).AIM To compare the long-and short-term outcomes of advanced GC patients who underwent LTG vs OTG following NAT.METHODS Advanced GC patients who underwent TG following NAT between April 2011 and May 2018 at the Cancer Hospital of the Chinese Academy of Medical Sciences were enrolled and stratified into two groups:LTG and OTG.Propensity score matching analysis was performed at a 1:1 ratio to overcome possible bias.RESULTS In total,185 patients were enrolled(LTG:78;OTG:109).Of these,138 were paired after propensity score matching.After adjustment for propensity score matching,baseline parameters were similar between the two groups.Compared to OTG,LTG was associated with a significantly shorter length of hospital stay(P=0.012).The rates of R0 resection,lymph node harvest,and postoperative morbidity did not significantly differ between the two groups.Overall survival(OS)outcomes were comparable between the two groups.Pathological T and N stages were found to be independent risk factors for OS.CONCLUSION LTG can be a feasible method for advanced GC patients following NAT,as it appears to be associated with better short-and comparable long-term outcomes compared to OTG.

Performance of Bayesian Propensity Score Adjustment for Estimating Causal Effects in Small Clinical Trials

Propensity score (PS) adjustment can control confounding effects and reduce bias when estimating treatment effects in non-randomized trials or observational studies. PS methods are becoming increasingly used to estimate causal effects, including when the sample size is small compared to the number of confounders. With numerous confounders, quasi-complete separation can easily occur in logistic regression used for estimating the PS, but this has not been addressed. We focused on a Bayesian PS method to address the limitations of quasi-complete separation faced by small trials. Bayesian methods are useful because they estimate the PS and causal effects simultaneously while considering the uncertainty of the PS by modelling it as a latent variable. In this study, we conducted simulations to evaluate the performance of Bayesian simultaneous PS estimation by considering the specification of prior distributions for model comparison. We propose a method to improve predictive performance with discrete outcomes in small trials. We found that the specification of prior distributions assigned to logistic regression coefficients was more important in the second step than in the first step, even when there was a quasi-complete separation in the first step. Assigning Cauchy (0, 2.5) to coefficients improved the predictive performance for estimating causal effects and improving the balancing properties of the confounder.

Temporal Variations in Mortality after Liver Transplantation: Retrospective Investigation of Potential Risk Factors Using Propensity Score

Objective: We aim to detect over-time variations in mortality of liver transplant recipients stratified by the period of transplant. Since this is a retrospective investigation, bias reduction caused by possible confounding effects can be achieved by using propensity score weighting in a multivariate logistic regression model. Methods: Medical charts of all adult liver transplant recipients (n = 250) who were transplanted in three periods 2005-2009, 2010-2014 and 2015-2019 were retrospectively reviewed. The following recipient factors were analyzed: recipients and donors’ ages, sex, renal impairment, body mass index (BMI), presence of bacterial or viral infections, MELD (Model for end-stage diseases). Multivariate logistic model adjusted by Propensity Scores (PS) was used to identify the effect of the risk factors on mortality, and death within five years, in the targeted time frame. Patient outcomes are recorded as;(patient status = 1 if dead, or patient status = 0 if alive). Results: Meld score, recipient age, and renal impairments were shown to be predictors of mortality in transplanted patients. Multivariate regression model was used to identify the significance of the specified risk factors, followed by pairwise comparisons between periods. Pairwise comparisons between periods using logistic regression weighted by the inverse propensity score, correcting for the possible confounding effect of measured covariates showed that the death rate is significantly reduced in subsequent periods as compared to the initial period. Conclusions: The clinical implications of these findings are the ability to stratify patients at high risk of posttransplant death by planning more intensive and accurate management for them.

Short-term and long-term outcomes of laparoscopic vs open ileocolic resection in patients with Crohn's disease: Propensityscore matching analysis

BACKGROUND Laparoscopic ileocolic resection(LICR)is the preferred surgical approach for primary ileocolic Crohn’s disease(CD)because it has greater recovery benefits than open ICR(OICR).AIM To compare short-and long-term outcomes in patients who underwent LICR and OICR.METHODS Patients who underwent ICR for primary CD from 2006 to 2017 at a single tertiary center specializing in CD were included.Patients who underwent LICR and OICR were subjected to propensity-score matching analysis.Patients were propensityscore matched 1:1 by factors potentially associated with 30-d perioperative morbidity.These included demographic characteristics and disease-and treatment-related variables.Factors were compared using univariate and multivariate analyses.Long-term surgical recurrence-free survival(SRFS)in the two groups was determined by the Kaplan-Meier method and compared by the log-rank test.RESULTS During the study period,348 patients underwent ICR,211 by the open approach and 137 laparoscopically.Propensity-score matching yielded 102 pairs of patients.The rate of postoperative complication was significantly lower(14%versus 32%,P=0.003),postoperative hospital stay significantly shorter(8 d versus 13 d,P=0.003),and postoperative pain on day 7 significantly lower(1.4 versus 2.3,P<0.001)in propensity-score matched patients who underwent LICR than in those who underwent OICR.Multivariate analysis showed that postoperative complications were significantly associated with preoperative treatment with biologics[odds ratio(OR):3.14,P=0.01]and an open approach to surgery(OR:2.86,P=0.005).The 5-and 10-year SRFS rates in the matched pairs were 92.9%and 83.3%,respectively,with SRFS rates not differing significantly between the OICR and LICR groups.The performance of additional procedures was an independent risk factor for surgical recurrence[hazard ratio(HR):3.28,P=0.02].CONCLUSION LICR yielded better short-term outcomes and postoperative recovery than OICR,with no differences in long-term outcomes.LICR may provide greater benefits in selected patients with primary CD.

Comparison of peg-interferon, ribavirin plus telaprevir vs simeprevir by propensity score matching

AIM: To compare efficacy of telaprevir(TVR) and simeprevir(SMV) combined with pegylated interferon(PEG-IFN) and ribavirin(RBV) while treating chronic hepatitis C(CHC). METHODS: In all, 306 CHC patients were included in this study. There were 159 patients in the TVR combination therapy group and 147 patients in the SMV combination therapy group. To evaluate pretreatment factors contributing to sustained virological response at 12 wk(SVR12), univariate and multivariate analyses were performed in TVR and SMV groups. To adjust for patient background between TVR and SMV groups, propensity score matching was performed. Virological response during treatment and SVR12 were evaluated.RESULTS: Overall rates of SVR12 [undetectable serum hepatitis C virus(HCV) RNA levels] were 79.2% and 69.4% in TVR and SMV groups, respectively. Patients in the SMV group were older, had higher serum HCV RNA levels, lower hemoglobin, higher prevalence of unfavorable interleukin-28B(IL28B) genotype(rs8099917), and poorer response to previous PEG-IFN and RBV treatment. Propensity score matching was performed to adjust for backgrounds(n = 104) and demonstrated SVR12 rates of 74.0% and 73.1% in the TVR and SMV groups, respectively. In the TVR group, discontinuation rates were higher because of adverse events; however, breakthrough and nonresponse was more frequent in the in SMV group. Multivariate analysis revealed IL28 B genotype(rs8099917) as the only independent predictive factor of SVR12 in both groups.CONCLUSION: SVR12 rates were almost identical following propensity score matching.

Clinicopathological characteristics and longterm survival of patients with synchronous multiple primary gastrointestinal stromal tumors: A propensity score matching analysis

BACKGROUND Multiple gastrointestinal stromal tumors(MGISTs)are specific and rare.Little is known about the impact of MGISTs on the survival of patients with gastrointestinal stromal tumors(GIST).The diagnosis,treatment and follow-up strategies of MGISTs is not specifically described in guidelines.AIM To compare the clinicopathological characteristics and prognosis of MGISTs and solitary GISTs(SGISTs)METHODS Patients diagnosed with primary GISTs from March 2010 to January 2020 were included.Due to the inhomogeneous distribution of several baseline characteristics and uneven MGIST and SGIST group sizes,propensity score matching was performed according to comorbidities,body mass index,tumor location,mitotic index,sex,age and American Society of Anesthesiologists score.Differences in clinicopathological characteristics and prognosis between patients with MGISTs and patients with SGISTs were compared.RESULTS Among the entire cohort of 983 patients,the incidence of MGISTs was 4.17%.Before matching,patients with MGISTs and those with SGISTs had disparities in body mass index,surgical approach,tumor size and mitotic index.After 1:4 ratio matching,the clinical baseline data were comparable.The 5-year progression-free survival rate was 52.17%in the MGIST group and 75.00%in the SGIST group(P=0.031).On multivariate analysis,tumor location,tumor size,mitotic index,imatinib treatment and MGISTs(hazard ratio=2.431,95%confidence interval=1.097-5.386,P=0.029)were identified as independent prognostic factors of progression-free survival.However,overall survival was similar between the SGIST and MGIST groups.CONCLUSION Patients with MGISTs had poorer progression-free survival than patients with SGISTs.Risk criteria and diagnostic and treatment strategies should be developed to achieve personalized precision therapy and maximize the survival benefit.

Real-world local recurrence rate after cold polypectomy in colorectal polyps less than 10 mm using propensity score matching

BACKGROUND Cold polypectomy(CP)is a simple and safe procedure for polyps less than 10 mm in size;however,there is concern about local recurrence following CP because of unidentified margins of excised specimens and the lack of tumor suppression effect by coagulation.Some clinical trials have evaluated local persistent recurrence;their results suggest that a higher rate of local recurrence has not been documented so far.There were few reports that observed the course over long periods of time after CP in clinical practice.AIM To evaluate the presence of local recurrence following CP and hot polypectomy(HP)using propensity score matching.METHODS We analyzed 275 patients who underwent polypectomy for non-pedunculated colorectal polyps less than 10 mm(959 Lesions)between October 2016 and 2017 and underwent follow-up endoscopy subsequently.We divided them into the CP group(706 Lesions),wherein CP was performed,and the HP group(253 Lesions),wherein HP was performed.Using propensity score matching,we extracted 215 Lesions in each group and evaluated the local recurrence and content of CP in the real clinic and adverse events using medical records.RESULTS After propensity score matching,there were no significant differences in the patients’and their endoscopic background(age,use of antithrombotics,indications,size,morphology,location of polyps,and polypectomy device)between the groups.The mean duration between colorectal polypectomy and the next follow-up colonoscopy was 17.5±7.1(range,6-39)mo in the CP group and 15.7±6.0(range,6-35)mo in the HP group,which was significantly longer in the CP group(P=0.005).The local recurrence rate was 0.93%in the CP group and 0.93%in the HP group,without a significant difference(P=0.688).Additionally,no differences were observed in the macroscopic en bloc resection rate,histopathological complete resection rate,and pathological results between the groups.Adverse events did not occur in either group.CONCLUSION Local recurrence after CP was equivalent to that following HP in clinical practice.CP is useful and safe in the treatment of non-pedunculated polyps of less than 10 mm.