Effects Of Selection Bias Research Articles

Survival of maxillary and mandibular bonded retainers 10 to 15\xa0years after orthodontic treatment: a retrospective observational study

BackgroundThe long-term evidence regarding failures of fixed retainers is limited and the aim of this cohort study was to assess the long-term risk of failure of one type of maxillary and two types of mandibular fixed lingual retainers.Trial designRetrospective cohort study.MethodsEighty-eight patients in retention 10–15 years after orthodontic treatment were included. The type of failure; number of failures per tooth, per patient, and retainer; and adverse effects were assessed by (1) a questionnaire, (2) clinical examination, and (3) screening patients’ clinical charts. Descriptive statistics were calculated and a Cox regression was used to assess possible predictors for mandibular retainer survival.Results and conclusionsIn the mandible, 47 (53.4%) .016″ × .022″ braided stainless steel retainers (SS) were bonded to all six anterior teeth, and 41 (46.6%) .027″ β-titanium (TMA) retainers were bonded to the canines only. From the SS retainers 40.4% and of the TMA retainers 61% had no failures during the whole observation period. SS failures per retainer were 2.17 (3.15) vs. 0.66 (1.03) for TMA. The type of retainer was the only significant predictor for failure. In the maxilla, 82 (93.2%) .016″ × .022″ braided SS retainers were bonded to all four incisors and six retainers (6.8%) to all six anterior teeth. The latter group was not further analyzed due to the small sample size. From the retainers bonded to all four incisors, 74.4% had no failure during the whole observation period. SS average number of failures per retainer bonded to the four incisors was 1.14 (SD 2.93). Overall, detachments were the most frequent type of first failure followed by composite damage. From the original mandibular retainers 98.9% and of the original maxillary retainers 97.6% were still in situ 10–15 years after debonding. No adverse torque changes were observed.LimitationsPotential effects of selection bias, information bias, and attrition bias as well as possible confounding factors cannot be fully excluded in this study.

Superior Located Papillary Thyroid Microcarcinoma is a Risk Factor for Lateral Lymph Node Metastasis.

It is important to identify prognostic factors for lateral lymph node metastasis (LLNM) in papillary thyroid microcarcinoma (PTMC) because they determine the extent of surgery. Several similarly designed studies have investigated predictors of LLNM, but with no more than 1000 cases. In addition, there are no recommendations or guidelines covering the differences in risk by tumor location. This study is the largest, using a papillary thyroid microcarcinoma population with 2967 patients. The purpose of this study is to address predictive factors of LLNM, focusing on lesion location. We retrospectively reviewed the data of 2967 PTMC patients who underwent total thyroidectomy and central neck dissection and/or lateral neck dissection (unilateral or bilateral) between January 1997 and June 2015. On multivariate analysis, superior lesion [adjusted odds ratio (OR) 3.32, p < 0.000], male gender (adjusted OR 1.39, p = 0.0047), age under 45years (adjusted OR 1.42, p = 0.015), and central lymph node metastasis (adjusted OR 3.40, p < 0.000) were significant predictors of high-risk LLNM. Superior lesion [hazard ratio (HR) 2.32, p = 0.005] and central lymph node metastasis (CLNM, HR 7.12, p < 0.000) were significant risk factors for locoregional recurrence (LRR). To reduce the effect of selection bias, we performed propensity score matching analysis with regard to tumor location. With a total of 1138 patients with matched data and 569 patients for each location, superior lesion (adjusted OR 3.17, p < 0.000), age under 45years (adjusted OR 1.73, p = 0.005), and CLNM (adjusted OR 2.77, p < 0.000) were independent predictive factors of LLNM. Superior lesion (HR 2.28, p = 0.04) and CLNM (HR 5.32, p = 0.001) were significant risk factors for LRR. In addition to young age, male gender, and CLNM identified in previous studies, meticulous assessment for LLNM is required in PTMC patients when lesions are located in the superior pole of the thyroid during preoperative evaluation or postoperative follow-up, because superior located papillary microcarcinoma is a risk factor for LLNM and LRR.

Randomization in survival studies: An evaluation method that takes into account selection and chronological bias

The random allocation of patients to treatments is a crucial step in the design and conduct of a randomized controlled trial. For this purpose, a variety of randomization procedures is available. In the case of imperfect blinding, the extent to which a randomization procedure forces balanced group sizes throughout the allocation process affects the predictability of allocations. As a result, some randomization procedures perform superior with respect to selection bias, whereas others are less susceptible to chronological bias. The choice of a suitable randomization procedure therefore depends on the expected risk for selection and chronological bias within the particular study in question. To enable a sound comparison of different randomization procedures, we introduce a model for the combined effect of selection and chronological bias in randomized studies with a survival outcome. We present an evaluation method to quantify the influence of bias on the test decision of the log-rank test in a randomized parallel group trial with a survival outcome. The effect of selection and chronological bias and the dependence on the study setting are illustrated in a sensitivity analysis. We conclude with a case study to showcase the application of our model for comparing different randomization procedures in consideration of the expected type I error probability.

Small Cell Deployment Along Roads: Coverage Analysis and Slice-Aware RAT Selection

We characterize a multi-tier wireless network consisting of multi-radio access technology (RAT) small cells, operating in both sub-6GHz and millimeter wave (mm-wave) bands, overlaid on top of traditional macro cells. To realistically characterize the user equipment (UE) performance, we model the position of the small cells along roads. First, we provide tractable, yet realistic models to characterize the mm-wave interference and the effect of vehicular blockages on the mm-wave signals. Then, we introduce an association policy, where an UE selects the serving tier using the powers measured on the sub-6GHz band, and then, using the biased power of the mm-wave band, selects the RAT. Based on this, we derive the signal to interference plus noise ratio (SINR) coverage probabilities of pedestrian UEs. We investigate the effect of the RAT selection bias on the vehicular blockage, SINR coverage, and rate coverage experienced by the UEs. Leveraging the results of our analysis, we propose to use a varied range of RAT selection biases to support the diverse applications of the fifth generation (5G) mobile networks. Accordingly, we provide a slice-aware RAT selection strategy to support three types of services, characterized by different requirements in terms of reliability, coverage, and data rates.

Extended follow-up in a randomized trial of hyperbaric oxygen for persistent post-concussive symptoms

To date, several Department of Defense (DoD) and civilian studies have evaluated hyperbaric oxygen for mild forms of traumatic brain injury. Prior to the DoD-sponsored "Brain Injury and Mechanisms of Action of Hyperbaric Oxygen for Persistent Post-Concussive Symptoms after Mild Traumatic Brain Injury (mTBI) (BIMA)" trial, none included post-intervention follow-up beyond three to six months. Post-hoc attempts at long-term follow-up were complicated by low participation and potential self-selection bias. BIMA planned for follow-up through 12 months but was amended to add post-concussive and post-traumatic stress disorder, quality of life, pain, depression, anxiety, and alcohol use assessments at 24 and 36 months. A total of 42 of 71 BIMA participants consented to extendedfollow-up, and 40 and 14 completed a 24- or 36-month visit, respectively, representing an overall response rate of 59% and 20%. Participants who completed extended follow-up were similar to the study group that did not in terms of demographics, perceived intervention allocation, and initial response to intervention. There were no significant differences at 24 or 36 months between intervention groups, and group mean scores were near pre-intervention values. This return to baseline could be due to waning treatment effect, selection bias, or participant or perception effects. Though BIMA implemented several participant retention strategies, more frequent participant contact and increased compensation might improve long-term retention in future studies. clinicaltrials.gov Identifier NCT01611194.

The Promotion Effect of Executive Compensation Stickiness on Corporate R&D Investment: Empirical Evidence Based on PSM

The impact of executive compensation stickiness on corporate R&D investment behavior is a new issue in the financial and financial field. A small amount of literature has analyzed the above issues, but they have ignored the possible adverse effects of sample selection bias on the research results. This paper takes the 2008-2016 China Shanghai and Shenzhen A-share listed companies as the research samples, uses propensity score matching (PSM) to empirically test whether the executive pay viscous significantly promotes R&D investment. The study found: under the premise of controlling sample selection bias, the R&D investment level of the executives with sticky and high-viscosity group is significantly higher than that of the sample companies with no sticky and low-viscosity groups. As a kind of salary incentive mechanism with failure tolerance characteristics, executive pay sticky has a significant promotion effect on Chinese R&D investment. Further research has also found that, especially for non-state-owned enterprises and high-tech enterprises, executive compensation stickiness has a stronger effect on corporate R&D investment.

Moving from prefabricated temporary housing to public reconstruction housing and social isolation after the Great East Japan Earthquake: a longitudinal study using propensity score matching

ObjectivesAfter the Great East Japan Earthquake (GEJE) of 2011, many survivors have been forced to live in prefabricated temporary housing, which is uncomfortable and insufficiently durable for permanent living. Public...

The Long-Term Effect of Cancer on Incident Stroke: A Nationwide Population-Based Cohort Study in Korea.

Background and Purpose: Despite the recent growing interest in the cancer–stroke association, the long-term effect, and organ-specific association with stroke incidence in subjects with cancer have not been clearly defined.Methods: Data were obtained from the Korean National Health Insurance Service National Sample Cohort database between 2002 and 2015. To investigate the effects of cancer on stroke incidence, subjects were classified into cancer and non-cancer groups based on the period after cancer diagnosis and origin organ of cancer. To minimize the effects of selection bias, we performed a propensity score matching analysis with covariates of demographic data, vascular risk factors, antithrombotics use and statin use. Incident stroke was diagnosed based on operational definition and classified into ischemic stroke and hemorrhagic stroke.Results: Data of 20,707 subjects with cancer and 675,594 without cancer were analyzed for 7 follow-up years. The subjects with cancer had higher risk of any stroke (subdistribution hazard ratio [SHR], 1.13; 95% confidence interval [CI], 1.02–1.26; p = 0.0181) than those without cancer. Similar trend was found for ischemic stroke (SHR, 1.17; 95% CI, 1.05–1.31; p = 0.0054), but not for hemorrhagic stroke. The risk of stroke was increased in subjects with cancer in the digestive organ, respiratory and intrathoracic organ, and “others (such as breast and female and male reproductive organs)” in 3 years; however, the association disappeared thereafter except those with “others” cancer. Chemotherapy increased the risk of ischemic stroke (SHR 1.21; 95% CI, 1.03–1.41).Conclusions: Cancer increases the risk of stroke at 3 years after the diagnosis of cancer, and the effect was maintained for 7 years. The association between cancer and stroke incidence depends on the organ from which the cancer originated and chemotherapy.

Retrospectively validating the results of the ACOSOG Z0011 trial in a large Asian Z0011-eligible cohort.

The Z0011 trial demonstrated that axillary dissection (ALND) could be omitted during breast-conserving therapy for cT1-2N0 breast cancers with 1-2 metastatic SLNs. However, that result has not been validated in a larger cohort and the significance of the small number of SLNs remains unclear. This study aimed to validate the Z0011 results within an Asian Z0011-eligible cohort and determine whether the number of sentinel lymph nodes (SLNs) influenced the Z0011-based outcomes. Data from Asian patients who fulfilled the Z0011 criteria were collected from five hospitals. Disease recurrence (DR) was compared between patients who underwent ALND or SLN dissection (SLND) alone. Propensity-score matching was performed to reduce the effects of potential selection biases. During 2010-2016, 1750 Asian patients had 1-2 SLN metastases and fulfilled the Z0011 criteria. These patients included 707 cases treated using SLND alone (40%) and 967 patients with ≤ 2 SLNs (55%). Ninety-five patients (5.4%) experienced DR at a median interval of 50 months, although the rates of DR were similar in the ALND and SLND groups. The adjusted hazard ratios for DR after ALND omission were 0.95 (95% CI 0.55-1.64) among the entire cohort and 0.83 (95% CI 0.34-2.03) among patients with ≤ 2 SLNs. In this Asian Z0011-eligible cohort, ALND omission did not increase risk of DR, even among patients with ≤ 2 SLNs. Therefore, the Z0011 strategy might be safely applied in Asia, and a small number of SLNs did not significantly influence this strategy.

Defining Exposures in Professional Football: Professional American-Style Football Players as an Occupational Cohort.

Studies of professional American football players have shown that football-related activities lead to acute injuries and may have long-term adverse health outcomes including osteoarthritis, neurocognitive impairment, and cardiovascular disease. However, the full complement of what constitutes professional football exposure has yet to be effectively articulated. Most likely, professional football exposure encompasses a multifaceted array of experiences including head impacts and joint stresses, long-term pain medication use, dietary restrictions, and strenuous training regimens. To study the health of professional American football players, characterizing the group as an occupational cohort and taking advantage of methods established within the discipline of occupational epidemiology may be beneficial. We conducted a narrative review of existing football research, occupational epidemiological methods papers, and occupational medicine studies. Here we describe the traditional occupational epidemiological approach to assessing exposure in a novel cohort and show how this framework could be implemented in studies of professional football players. In addition, we identify the specific challenges associated with studying an elite athletic occupational group, including the healthy worker effect and other types of selection and information biases, and explore these in the context of existing studies of football-related health. The application of well-established occupational epidemiological methods to professional football players may yield new insights into the effects of playing exposure and may provide opportunities for interventions to reduce harm.

Multicenter, retrospective, comparative study of laparoscopic and open Kasai portoenterostomy in children with biliary atresia from Japanese high‐volume centers

Multicenter study was undertaken to analyze the results of laparoscopic and open Kasai portoenterostomy. Subjects were infants with type III biliary atresia who underwent open operation (n = 106) or laparoscopic operation (n = 21) between January 2012 and December 2015. Clinical data were compared between open and laparoscopic operations (2016-0534). Propensity score matching was performed to reduce the effect of treatment selection bias. Multivariate analyses were used to estimate the effect of the surgical approach on the jaundice clearance rate and the native liver survival rate. The postoperative jaundice clearance rate and the 1-year native liver survival rate were not significantly different between open and laparoscopic operations. Rates of cholangitis and major complications of laparoscopic operation were comparable to those of open operation. Blood loss, time to resume oral intake, time to drain removal, and duration of analgesic usage of laparoscopic operation were significantly superior to those of open operation. Similar results were observed when analysis was adjusted based on propensity score. Multivariate analyses demonstrated that only age at operation was a poor prognostic factor. Laparoscopic Kasai portoenterostomy was associated with several favorable perioperative outcomes compared with open Kasai portoenterostomy. The difference of surgical approach was not a significant independent predictor.

Colorectal polyps located across a fold are difficult to resect completely using endoscopic mucosal resection: A propensity score analysis.

Incomplete polyp resection during colorectal endoscopic mucosal resection (EMR) might contribute to the development of interval cancer. This retrospective study aimed to determine the incidence of incomplete polyp resection during EMR of colorectal polyps located across a fold compared with that of colorectal polyps located between folds. In total, 262 patients with 262 lesions that were ≥10 mm in diameter and treated with conventional EMR were enrolled. The main outcome was the incidence of incomplete polyp resections. Propensity score matching and inverse probability of treatment weighting (IPTW) were performed to reduce the effects of selection bias. Fifty-seven lesions (21.8%) were incompletely resected. After propensity score matching, the lesions located across a fold were at higher risk of incomplete resection than those between folds (26/68, 38.2% vs 7/68, 10.3%; odds ratio (OR): 3.71; 95% confidence interval (CI): 1.61-8.56; p < 0.01). These findings persisted after adjusting for the differences at baseline using the IPTW method (OR: 3.63; 95% CI: 1.72-7.63; p = 0.001). There is an increased risk of an incomplete polyp resection for a colorectal polyp that is located across a fold compared with that for a polyp that is located between folds.

Quantifying codon usage in signal peptides: Gene expression and amino acid usage explain apparent selection for inefficient codons

The Sec secretion pathway is found across all domains of life. A critical feature of Sec secreted proteins is the signal peptide, a short peptide with distinct physicochemical properties located at the N-terminus of the protein. Previous work indicates signal peptides are biased towards translationally inefficient codons, which is hypothesized to be an adaptation driven by selection to improve the efficacy and efficiency of the protein secretion mechanisms. We investigate codon usage in the signal peptides of E. coli using the Codon Adaptation Index (CAI), the tRNA Adaptation Index (tAI), and the ribosomal overhead cost formulation of the stochastic evolutionary model of protein production rates (ROC-SEMPPR). Comparisons between signal peptides and 5′-end of cytoplasmic proteins using CAI and tAI are consistent with a preference for inefficient codons in signal peptides. Simulations reveal these differences are due to amino acid usage and gene expression – we find these differences disappear when accounting for both factors. In contrast, ROC-SEMPPR, a mechanistic population genetics model capable of separating the effects of selection and mutation bias, shows codon usage bias (CUB) of the signal peptides is indistinguishable from the 5′-ends of cytoplasmic proteins. Additionally, we find CUB at the 5′-ends is weaker than later segments of the gene. Results illustrate the value in using models grounded in population genetics to interpret genetic data. We show failure to account for mutation bias and the effects of gene expression on the efficacy of selection against translation inefficiency can lead to a misinterpretation of codon usage patterns.

Clinical value of Oxford acute severity of illness score in identifying quick sequential organ failure assessment-negative patients with sepsis

Objective: The quick sequential organ failure assessment (qSOFA) score has been proposed as part of diagnostic criteria for sepsis, but there might be an underestimation of the incidence of qSOFA-negative sepsis according to a few recent studies. The purpose of this study was to evaluate the value of Oxford acute severity of illness score (OASIS) in identifying qSOFA-negative (qSOFA<2) patients with sepsis. Methods: Sepsis patients with negative qSOFA scores were selected from the Medical Information Mart for Intensive Care Ⅲ(MIMIC-Ⅲ), a database comprising de-identified health-related data from patients staying in the critical care units of Beth Israel Deaconess Medical Center between 2001 and 2012. Non-infectious patients with both qSOFA and SOFA scores less than 2 were enrolled as controls. Propensity score matching (PSM) analysis was used to reduce the effects of selection bias. Receiver operating characteristic (ROC) curve analysis was performed to assess the value of OASIS in discriminating qSOFA-negative patients with sepsis and to determine its optimal cut-off. Associations of OASIS with 28-day mortality after intensive care unit (ICU) admission, ICU mortality, and hospital mortality were further examined using multivariate Cox regression and multivariate logistic regression analysis. Results: 2 273 qSOFA-negative patients with sepsis and 3 342 non-sepsis controls were included finally with a PSM cohort consisted of 1 677 sepsis patients and 1 677 controls. Results of ROC analysis showed that the area under ROC curve was 0.753 [95% confidence interval (CI) 0.741-0.765] and the optimal OASIS threshold according to the Youden index was 26.5 and yielded a 67.2% sensitivity and 70.8% specificity. Multivariate regression analysis indicated that OASIS>26 was an independent risk factor for 28-day mortality (hazard ratio 2.80, 95% CI 2.15-3.65, P<0.01), ICU mortality (odds ratio 4.69, 95% CI 2.60-8.49, P<0.01), and hospital mortality (odds ratio 4.48, 95% CI 3.13-6.42, P<0.01). Analysis of the PSM cohort presented consistent results. Conclusions: OASIS had a good discriminative value to differentiate qSOFA-negative patients with sepsis from those without sepsis.

Impact of Breast Reconstruction on Time to Definitive Surgical Treatment, Adjuvant Therapy, and Breast Cancer Outcomes.

Delays in surgery and adjuvant treatment for breast cancer are associated with decreased survival. However, the time between diagnosis and surgery is rising, partly attributed to the added complexity of immediate breast reconstruction (IBR). We sought to investigate time to treatment and survival outcomes in breast cancer patients undergoing IBR. We performed a retrospective review of 2004-2014 California Cancer Registry data for stage 0-III breast cancer patients undergoing mastectomy. Time to surgery, adjuvant systemic therapy and radiation therapy, propensity score, and covariate-adjusted overall mortality hazard ratios (HRs) were assessed by IBR status. Of 56,782 patients, 13,738 (24.2%) underwent IBR, with a median follow-up of 68.8months. Median time between diagnosis and surgery was increased for patients undergoing IBR compared with those without {49days (interquartile range [IQR] 34-73) vs. 35days (IQR 21-56), p < 0.001}. IBR did not affect the interval from surgery to adjuvant chemotherapy or radiation, but prolonged time to endocrine therapy by 5days (p = 0.014). Significantly lower survival was observed when time to surgery exceeded 120days (vs. 0-30days; HR 1.14 [1.02-1.28], p = 0.023), and improved survival with IBR (vs. without; HR 0.67 [0.61-0.74], p < 0.001). The benefit associated with reconstruction persisted for all age groups except age 80 + years, while surgical delay > 120days demonstrated significantly lower survival in women < 60years of age. While IBR delays time to definitive surgery, its use did not substantially affect time to adjuvant treatment or survival outcomes. Further research is ongoing to mitigate the effects of potential selection bias in favor of IBR.

Association between peri-operative angiotensin-converting enzyme inhibitors and angiotensin-2 receptor blockers and acute kidney injury in major elective non-cardiac surgery: a multicentre, prospective cohort study.

The peri-operative use of angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers is thought to be associated with an increased risk of postoperative acute kidney injury. To reduce this risk, these agents are commonly withheld during the peri-operative period. This study aimed to investigate if withholding angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers peri-operatively reduces the risk of acute kidney injury following major non-cardiac surgery. Patients undergoing elective major surgery on the gastrointestinal tract and/or the liver were eligible for inclusion in this prospective study. The primary outcome was the development of acute kidney injury within seven days of operation. Adjusted multi-level models were used to account for centre-level effects and propensity score matching was used to reduce the effects of selection bias between treatment groups. A total of 949 patients were included from 160 centres across the UK and Republic of Ireland. From this population, 573 (60.4%) patients had their angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers withheld during the peri-operative period. One hundred and seventy-five (18.4%) patients developed acute kidney injury; there was no difference in the incidence of acute kidney injury between patients who had their angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers continued or withheld (107 (18.7%) vs. 68 (18.1%), respectively; p = 0.914). Following propensity matching, withholding angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers did not demonstrate a protective effect against the development of postoperative acute kidney injury (OR (95%CI) 0.89 (0.58-1.34); p = 0.567).

116 SUCCESSFUL ERADICATION OF HELICOBACTER PYLORI REDUCES THE DEVELOPMENT OF METACHRONOUS GASTRIC CANCER AFTER ENDOSCOPIC SUBMUCOSAL DISSECTION FOR EARLY GASTRIC CANCER: A PROPENSITY MATCHING ANALYSIS

Helicobacter pylori infection is the most important risk factor for gastric cancer. Some randomized studies showed that successful H. pylori eradication after endoscopic resection of early gastric cancer (EGC) significantly reduced metachronous gastric cancer (MGC), whereas others showed that H. pylori eradication did not significantly contribute to reducing MGC. Our aim was to investigate the effect of H. pylori eradication on the development of MGC after endoscopic submucosal dissection (ESD) for EGC. Between October 2007 and October 2015, at our hospital, 701 consecutive patients with EGC underwent curative resection using the expanded indications for ESD according to the criteria in the Japanese Gastric Cancer Treatment Guidelines 2014. Of these patients, 378 who contracted H. pylori infection at the time of ESD were enrolled. Patients with familial adenomatous polyposis, those who had undergone surgical gastrectomy, or those whose follow-up duration was less than 1 year, were excluded. The patients included were divided into two groups as follows: those who failed or did not undergo H. pylori eradication (persistent group, n = 220), and those who successfully underwent H. pylori eradication (eradicated group, n = 128). We retrospectively compared the incidence of the development of MGC between the groups by using propensity score (PS) matching to reduce the effects of selection bias and potential confounding factors. The patients in the persistent group had significantly older age, lighter weight, and larger tumor size than the patients in the eradicated group (p < 0.01, p = 0.05, p = 0.01). After PS matching, 128 pairs of patients between the persistent and eradicated groups showed no significant difference in any covariate. The MGC developed in 22 patients (10.0%) in the persistent group and 5 patients (3.9%) in the eradicated group during the median follow-up period of 38.8 months (range, 12.4–114.0 months) and 40.5 months (range, 25.9–105.7 months), respectively. Before matching, the 5-year cumulative incidence rate of MGC was not significantly different between the persistent and eradicated groups (11.3% vs 3.8%, p = 0.06). After matching, the rate was significantly higher in the persistent group than the eradicated group (14.2% vs 3.8%, p = 0.01). In the Cox proportional hazard analysis, the eradicated group was not significantly associated with preventing MGC before matching (HR = 0.40, p = 0.07). However, the eradicated group was significantly associated with preventing MGC after matching (HR = 0.30, p = 0.02). Although this is a retrospective cohort study conducted at a single institution by using PS matching to adjust the background factors in the real world, it demonstrated that successful H. pylori eradication may reduce the development of MGC after ESD of EGC.

Risk of fragility fracture among patients with gout and the effect of urate-lowering therapy.

Previous studies that quantified the risk of fracture among patients with gout and assessed the potential effect of urate-lowering therapy have provided conflicting results. Our study aims to provide better estimates of risk by minimizing the effect of selection bias and confounding on the observed association. We used data from the Clinical Practice Research Datalink, which records primary care consultations of patients from across the United Kingdom. We identified patients with incident gout from 1990 to 2004 and followed them up until 2015. Each patient with gout was individually matched to 4 controls on age, sex and general practice. We calculated absolute rate of fracture and hazard ratios (HRs) using Cox regression models. Among patients with gout, we assessed the impact of urate-lowering therapy on fracture, and used landmark analysis and propensity score matching to account for immortal time bias and confounding by indication. We identified 31 781 patients with incident gout matched to 122 961 controls. The absolute rate of fracture was similar in both cases and controls (absolute rate = 53 and 55 per 10 000 person-years, respectively) corresponding to an HR of 0.97 (95% confidence interval 0.92-1.02). Our finding remained unchanged when we stratified our analysis by age and sex. We did not observe statistically significant differences in the risk of fracture among those prescribed urate-lowering therapy within 1 and 3 years after gout diagnosis. Overall, gout was not associated with an increased risk of fracture. Urate-lowering drugs prescribed early during the course of disease had neither adverse nor beneficial effect on the long-term risk of fracture.

Comparison of endoscopic submucosal dissection and surgery for superficial esophageal squamous cell carcinoma: a propensity score-matched analysis

Endoscopic submucosal dissection (ESD) has been widely accepted for treating superficial esophageal squamous cell carcinoma (SESCC). However, long-term outcomes of ESD and esophagectomy for SESCC have not been compared. We compared the clinical outcomes of ESD and esophagectomy in a matched cohort. Patients who underwent ESD and esophagectomy for SESCC were included. We selected SESCCs without obvious submucosal invasion from the surgical database by reviewing endoscopic images. To minimize the effect of selection bias, propensity score matching was performed. Overall survival (OS), disease-specific survival (DSS), recurrence-free survival (RFS), and metachronous RFS were compared between the 2 groups. Adverse event rates were also compared. In a matched cohort of 120 pairs, OS, DSS, and RFS were comparable between the 2 groups. The 5-year OS, DSS, and RFS rates were 93.9% versus 91.2%, 100% versus 97.4%, and 92.8% versus 95.3% for the ESD and esophagectomy groups, respectively. The metachronous RFS was worse in the ESD group than in the esophagectomy group (P= .004). The 5-year metachronous RFS rates were 90.3% versus 100% for the ESD and esophagectomy groups, respectively. The esophagectomy group showed a higher overall adverse event rate than the ESD group (55.5% vs 18.5%, P< .0001). In each subgroup of mucosal and submucosal cancer, OS, DSS, and RFS were also comparable between the 2 groups. ESD provides long-term outcomes comparable with esophagectomy in patients with SESCC without endoscopic evidence of obvious submucosal invasion. ESD should be considered as the first-line treatment for these patients.

Long-term survival of patients with thyroid cancer according to the methods of tumor detection: A nationwide cohort study in Korea.

In this retrospective cohort study, we compared the survival of patients detected by screening with those detected based on symptoms, according to their tumor stages. After propensity score matching, 2,130 patients with papillary or follicular thyroid cancer, identified by screening detection (SD) and clinical detection (CD), were included. We compared the survival rates of patients identified by SD and CD in the early and advanced stages of thyroid cancer. Cox proportional hazard models were used to compare the hazard ratios (HRs) for mortality between the two groups. Of the 1,065 patients in each group, 12 (1.1%) died in the SD group, compared to 44 (4.1%) in the CD group, during an average 9.4 years (p<0.001). For early stage, there was no significant difference in all-cause and thyroid cancer-specific mortality between the two groups (p = 0.08, p = 0.0502). However, for advanced stage, the survival rates in the SD group were significantly higher than in the CD group (p<0.001, p = 0.004). Moreover, after adjusting for covariates, the HRs of all-cause mortality of the SD group was significantly lower than that of the CD group for the advanced stage patients (HRs: 0.37 [95% CIs: 0.17–0.80]), while no significant difference was observed in the early stage. While screening for thyroid cancer was not beneficial for early stage patients, our findings suggest that detection via screening is associated with better survival for patients with advanced stage cancer. However, the effects of selection bias and lead time bias could not be entirely excluded.