Indika Mallawaarachchi

Gastric polyps: Association with Helicobacter pylori status and the pathology of the surrounding mucosa, a cross sectional study.

AIM To assess the endoscopic characteristics of gastric polyps and their association with Helicobacter pylori (H. pylori) status in a predominantly Hispanic population. METHODS We conducted a retrospective study of all esophagogastroduodenoscopies performed at our institution. Demographic, endoscopic and histopathological data were reviewed. Categorization of patients into Hispanic and Non-Hispanic was based on self-identification. Patients without resection/biopsy were not included in the analysis. Identification of polyps type was based on histological examination. One way analysis of variance was used to compare continuous variables among different polyp types and Fishers exact test was used compare categorical variables among polyp types. Unadjusted and adjusted comparisons of demographic and clinical characteristics were performed according to the H. pylori status and polyp type using logistic regressions. RESULTS Of 7090 patients who had upper endoscopy, 335 patients had gastric polyps (4.7%). Resection or biopsy of gastric polyps was performed in 296 patients (88.4%) with a total of 442 polyps removed or biopsied. Of 296 patients, 87 (29%) had hyperplastic polyps, 82 (28%) had fundic gland polyps and 5 (1.7%) had adenomatous polyps. Hyperplastic polyps were significantly associated with positive H. pylori status compared with fundic gland polyps (OR = 4.621; 95%CI: 1.92-11.13, P = 0.001). Hyperplastic polyps were also found to be significantly associated with portal hypertensive gastropathy compared with fundic gland polyps (OR = 6.903; 95%CI: 1.41-33.93, P = 0.0174). Out of 296 patients, 30 (10.1%) had a follow-up endoscopy with a mean duration of 26 ± 16.3 mo. Interval development of cancer was not noted in any of the patients during follow up period. CONCLUSION Gastric hyperplastic polyps were significantly associated with positive H. pylori status and portal hypertensive gastropathy as compared with fundic gland polyps.

Methods for estimating relative risk in studies of common binary outcomes

Studying the effect of exposure or intervention on a dichotomous outcome is very common in medical research. Logistic regression (LR) is often used to determine such association which provides odds ratio (OR). OR often overestimates the effect size for prevalent outcome data. In such situations, use of relative risk (RR) has been suggested. We propose modifications in Zhang and Yu and Diaz-Quijano methods. These methods were compared with stratified Mantel Haenszel method, LR, log binomial regression (LBR), Zhang and Yu method, Poisson/Cox regression, modified Poisson/Cox regression, marginal probability method, COPY method, inverse probability of treatment weighted LBR, and Diaz-Quijano method. Our proposed modified Diaz-Quijano (MDQ) method provides RR and its confidence interval similar to those estimated by modified Poisson/Cox and LBRs. The proposed modifications in Zhang and Yu method provides better estimate of RR and its standard error as compared to Zhang and Yu method in a variety of situations with prevalent outcome. The MDQ method can be used easily to estimate the RR and its confidence interval in the studies which require reporting of RRs. Regression models which directly provide the estimate of RR without convergence problems such as the MDQ method and modified Poisson/Cox regression should be preferred.

A prospective study of the risk of bacteremia in directed cholangioscopic examination of the common bile duct.

BACKGROUND AND AIMS The frequency of bacteremia during ERCP with cholangioscopy has not been well studied. There are no formal guidelines regarding antibiotic prophylaxis before ERCP with cholangioscopy. The aim was to estimate the frequency of bacteremia and subsequent infectious adverse events after ERCP with cholangioscopy. METHODS This prospective nonrandomized study performed in a single tertiary referral center included adult patients who were undergoing ERCP with cholangioscopic examination of the common bile duct. Blood cultures were drawn from patients before the procedure and 5 and 30 minutes after the procedure. Antibiotics were not given before or after the procedure. Patients were followed up after 24 hours and 1 week after the procedure for infectious adverse events. The primary outcome was bacteremia rate, and secondary outcomes were cholangitis rate and adverse events. RESULTS Fifty-seven patients were enrolled in the study with 60 procedures performed. The first procedure from each patient was considered in the analysis, and thus we included 57 patients with 57 procedures in this study analysis. Postprocedure bacteremia was seen in 5 of 57 procedures (8.8%; 95% confidence interval, 2.9%-19.3%). Four patients were readmitted with cholangitis (7.0%). Bacteremia was more common in patients who had cholangioscopy with biopsy sampling compared with patients who had cholangioscopy without biopsy sampling (P = .011). Cholangitis was significantly more common in patients with bacteremia than in those patients with a negative blood culture (P = .035). CONCLUSION ERCP with cholangioscopy is associated with a bacteremia rate of 8.8% and a cholangitis rate of 7.0%. Preprocedural antibiotics may be considered before cholangioscopy, especially if tissue acquisition with biopsy sampling is expected. ( CLINICAL TRIAL REGISTRATION NUMBER NCT01673269.).

Analysis of small sample size studies using nonparametric bootstrap test with pooled resampling method

Experimental studies in biomedical research frequently pose analytical problems related to small sample size. In such studies, there are conflicting findings regarding the choice of parametric and nonparametric analysis, especially with non-normal data. In such instances, some methodologists questioned the validity of parametric tests and suggested nonparametric tests. In contrast, other methodologists found nonparametric tests to be too conservative and less powerful and thus preferred using parametric tests. Some researchers have recommended using a bootstrap test; however, this method also has small sample size limitation. We used a pooled method in nonparametric bootstrap test that may overcome the problem related with small samples in hypothesis testing. The present study compared nonparametric bootstrap test with pooled resampling method corresponding to parametric, nonparametric, and permutation tests through extensive simulations under various conditions and using real data examples. The nonparametric pooled bootstrap t-test provided equal or greater power for comparing two means as compared with unpaired t-test, Welch t-test, Wilcoxon rank sum test, and permutation test while maintaining type I error probability for any conditions except for Cauchy and extreme variable lognormal distributions. In such cases, we suggest using an exact Wilcoxon rank sum test. Nonparametric bootstrap paired t-test also provided better performance than other alternatives. Nonparametric bootstrap test provided benefit over exact Kruskal-Wallis test. We suggest using nonparametric bootstrap test with pooled resampling method for comparing paired or unpaired means and for validating the one way analysis of variance test results for non-normal data in small sample size studies. Copyright

Estimation of the Adenoma Detection Rate From the Polyp Detection Rate by Using a Conversion Factor in a Predominantly Hispanic Population.

Background: Calculating the adenoma detection rate (ADR) is a complex process in contrast to the polyp detection rate (PDR) that can be easily calculated. The average adenoma to polyp detection rate quotient (APDRQ) was proposed as a conversion factor to estimate the ADR for individual endoscopists from the endoscopist’s PDR. However, this conversion factor was not validated in different practice settings. Goal: To validate the use of the proposed conversion factor in a practice setting with a predominantly Hispanic population. Study: We conducted a retrospective, cross-sectional study (December 2007 to November 2012) of screening colonoscopies at a university practice setting with an 86.9% Hispanic population. The actual ADR and PDR were calculated for all endoscopists. The weighted average of ADR to PDR ratio for each endoscopist was used to obtain APDRQ. The APDRQ was used as a conversion multiplier to estimate each endoscopist’s ADR using the single endoscopist’s PDR. Results: A total of 2148 screening colonoscopies were included. The average PDR for the whole group was 36.9% (range, 11% to 49%). The actual ADR was estimated as 25.5% (range, 11% to 37%). The average APDRQ for our group was 0.68. The estimated ADR was 25.48% (range, 8% to 33%). There was a high correlation between actual ADR and the estimated ADR (Pearson correlation=0.92). Conclusions: In a practice setting with a predominantly Hispanic population, a conversion factor can be used to estimate ADR from PDR providing a high degree of correlation with the actual ADR.

Glucose Levels and Depression in Hispanic Patients Admitted to the Cardiovascular Intensive Care Unit A Cross-Sectional Study

Depression is frequently associated with diabetes mellitus (DM) and may worsen DM-related morbidity and mortality. We determined the potential association of glucose levels with depression in Hispanic patients admitted to the Cardiovascular Intensive Care Unit. Patients were given the Center for Epidemiologic Studies—Depression scale survey within 24 hours of admission. Glycated hemoglobin and fasting blood glucose levels within 30 days of admission were extracted. The HbA1c levels remained significantly associated with both presence of depression and depression levels. Histories of DM, myocardial infarction, and percutaneous coronary intervention as well as baseline brain natriuretic peptide levels were also significantly associated with depression levels. The presence of a significant association between glucose levels and depression in Hispanic patients indicates that there is a need for optimal management of glycemic levels. This may then lead to better health outcomes in Hispanics with cardiovascular disease.

Aggression toward Familiar People, Strangers, and Conspecifics in Gonadectomized and Intact Dogs

Gonadectomy is widely used to treat and prevent behavior problems including the aggressive behavior of dogs. The aim of this study was to determine whether aggressive behavior toward familiar people, strangers, or other dogs was significantly different in dogs gonadectomized at various ages vs. intact dogs using the Canine Behavioral Assessment Research Questionnaire (C-BARQ) with multivariate analysis. Of 15,370 initial surveys, those for dogs reported to have been gonadectomized at less than 6 weeks of age or to correct a behavior problem, and those with incomplete answers to questions regarding independent or dependent variables were excluded, leaving 13,795 for the analysis of aggressive behavior toward familiar people: 13,498 for aggressive behavior toward strangers and 13,237 for aggressive behavior toward dogs. Aggressive behavior was defined (a) using mean scores for all questions on the C-BARQ for aggressive behavior (range 0–4) and (b) comparing dogs with no aggressive behavior (all questions answered 0) to dogs with moderate or severe aggression (at least one score of 2, 3, or 4). Data for intact dogs were compared with those for dogs gonadectomized at 6 months or less, 7–12 months, 11–18 months, and >18 months. Neither gonadectomy nor age at gonadectomy showed an association with aggression toward familiar people or dogs. However, there was a low but significant increase in the odds of moderate or severe aggression toward strangers for all gonadectomized dogs compared with intact dogs, but this effect was driven entirely by data for dogs gonadectomized at 7–12 months of age, which were 26% more likely to demonstrate aggression toward strangers. This large, comprehensive study of the relationships between gonadectomy and aggressive behavior in dogs demonstrates that when the many factors affecting aggressive behavior are considered, there is no evidence that gonadectomy at any age alters aggressive behavior toward familiar people or dogs, and there is only a minimal increase in aggression toward strangers. Given the increasing evidence of significant negative health effects of gonadectomy, there is an urgent need to systematically examine other means of preventing unwanted procreation, such as vasectomy and hysterectomy.

Effects of Starting a Gastroenterology Fellowship Training Program on Quality Measures of Colonoscopy.

Objectives Adenoma detection rate (ADR) is the most established indicator of the quality of screening colonoscopy. The effect of gastroenterology (GI) fellows on the quality of screening colonoscopies has been evaluated previously; however, the effect of starting a new GI fellowship program on the quality of screening colonoscopies has not been studied. The aim of our study was to assess the effects of starting a GI fellowship program and the participation of fellows in screening colonoscopies on ADR and other measures of quality. Methods This was a retrospective, cross-sectional study of all screening colonoscopies performed 20 months before and 20 months after starting the GI fellowship at our medical center (November 2010–February 2014). Colonoscopy procedure notes and pathology records were reviewed for each patient. Data from the two periods were compared using either the Fisher exact test or the two-sample t test. Results A total of 2127 complete colonoscopies were included in the analysis. The mean age of patients was 58.8 ± 6.6 years. Of the 2127 colonoscopies, GI fellows were involved in 385 (18%), whereas 1742 (82%) were performed solely by GI attendings (attending physicians). Multivariate analysis using relative risk (RR) of regression was done. The after starting the GI fellowship period was significantly associated with an increase in ADR (RR 1.19, 95% confidence interval 1.10–1.30, P < 0.001) and advanced adenoma detection rate (RR 1.17, 95% confidence interval 1.00–1.38, P < 0.001) compared with the before starting the GI fellowship period. In the after starting the GI fellowship period, the polyp detection rate and ADR for colonoscopies performed by the attending physicians with the fellows were significantly higher than colonoscopies performed solely by the same attendings (58.4% vs 44.5%, P = 0.001, 42.0% vs 32.9%, P = 0.017, respectively). Conclusions Starting a GI fellowship program significantly increased the polyp detection rate, ADR, and advanced ADR.