Objective: Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we assessed the prevalence of bias in published meta-analyses. Design: Medline search to identify pairs consisting of a meta-analysis and a single large trial (concordance of results was assumed if effects were in the same direction and the meta-analytic estimate was within 30% of the trial); analysis of funnel plots from 37 meta-analyses identified from a hand search of four leading general medicine journals 1993-6 and 38 meta-analyses from the second 1996 issue of the Cochrane Database of Systematic Reviews . Main outcome measure: Degree of funnel plot asymmetry as measured by the intercept from regression of standard normal deviates against precision. Results: In the eight pairs of meta-analysis and large trial that were identified (five from cardiovascular medicine, one from diabetic medicine, one from geriatric medicine, one from perinatal medicine) there were four concordant and four discordant pairs. In all cases discordance was due to meta-analyses showing larger effects. Funnel plot asymmetry was present in three out of four discordant pairs but in none of concordant pairs. In 14 (38%) journal meta-analyses and 5 (13%) Cochrane reviews, funnel plot asymmetry indicated that there was bias. Conclusions: A simple analysis of funnel plots provides a useful test for the likely presence of bias in meta-analyses, but as the capacity to detect bias will be limited when meta-analyses are based on a limited number of small trials the results from such analyses should be treated with considerable caution. Key messages Systematic reviews of randomised trials are the best strategy for appraising evidence; however, the findings of some meta-analyses were later contradicted by large trials Funnel plots, plots of the trials9 effect estimates against sample size, are skewed and asymmetrical in the presence of publication bias and other biases Funnel plot asymmetry, measured by regression analysis, predicts discordance of results when meta-analyses are compared with single large trials Funnel plot asymmetry was found in 38% of meta-analyses published in leading general medicine journals and in 13% of reviews from the Cochrane Database of Systematic Reviews Critical examination of systematic reviews for publication and related biases should be considered a routine procedure

/pdf/bias-in-meta-analysis-detected-by-a-simple-graphical-test-5erh428s5c.pdf

Bias in meta-analysis detected by a simple, graphical test

ContextConventional nonsteroidal anti-inflammatory drugs (NSAIDs) are associated
with a spectrum of toxic effects, notably gastrointestinal (GI) effects, because
of inhibition of cyclooxygenase (COX)-1. Whether COX-2–specific inhibitors
are associated with fewer clinical GI toxic effects is unknown.ObjectiveTo determine whether celecoxib, a COX-2–specific inhibitor, is
associated with a lower incidence of significant upper GI toxic effects and
other adverse effects compared with conventional NSAIDs.DesignThe Celecoxib Long-term Arthritis Safety Study (CLASS), a double-blind,
randomized controlled trial conducted from September 1998 to March 2000.SettingThree hundred eighty-six clinical sites in the United States and Canada.ParticipantsA total of 8059 patients (≥18 years old) with osteoarthritis (OA)
or rheumatoid arthritis (RA) were enrolled in the study, and 7968 received
at least 1 dose of study drug. A total of 4573 patients (57%) received treatment
for 6 months.InterventionsPatients were randomly assigned to receive celecoxib, 400 mg twice per
day (2 and 4 times the maximum RA and OA dosages, respectively; n = 3987);
ibuprofen, 800 mg 3 times per day (n = 1985); or diclofenac, 75 mg twice per
day (n = 1996). Aspirin use for cardiovascular prophylaxis (≤325 mg/d)
was permitted.Main Outcome MeasuresIncidence of prospectively defined symptomatic upper GI ulcers and ulcer
complications (bleeding, perforation, and obstruction) and other adverse effects
during the 6-month treatment period.ResultsFor all patients, the annualized incidence rates of upper GI ulcer complications
alone and combined with symptomatic ulcers for celecoxib vs NSAIDs were 0.76%
vs 1.45% (P = .09) and 2.08% vs 3.54% (P = .02), respectively. For patients not taking aspirin, the annualized
incidence rates of upper GI ulcer complications alone and combined with symptomatic
ulcers for celecoxib vs NSAIDs were 0.44% vs 1.27% (P
= .04) and 1.40% vs 2.91% (P = .02). For patients
taking aspirin, the annualized incidence rates of upper GI ulcer complications
alone and combined with symptomatic ulcers for celecoxib vs NSAIDs were 2.01%
vs 2.12% (P = .92) and 4.70% vs 6.00% (P = .49). Fewer celecoxib-treated patients than NSAID-treated patients
experienced chronic GI blood loss, GI intolerance, hepatotoxicity, or renal
toxicity. No difference was noted in the incidence of cardiovascular events
between celecoxib and NSAIDs, irrespective of aspirin use.ConclusionsIn this study, celecoxib, at dosages greater than those indicated clinically,
was associated with a lower incidence of symptomatic ulcers and ulcer complications
combined, as well as other clinically important toxic effects, compared with
NSAIDs at standard dosages. The decrease in upper GI toxicity was strongest
among patients not taking aspirin concomitantly.

https://jamanetwork.com/journals/jama/articlepdf/193062/JOC01227.pdf

Gastrointestinal Toxicity With Celecoxib vs Nonsteroidal Anti-inflammatory Drugs for Osteoarthritis and Rheumatoid Arthritis: The CLASS Study: A Randomized Controlled Trial

One hundred years have passed since Felix Hoffman, working at Bayer Industries, reported the successful synthesis of acetylsalicylic acid as the first nonsteroidal antiinflammatory drug (NSAID).1,2 At the suggestion of Hermann Dreser, Bayer's chief pharmacologist at the time,3 the compound was called “aspirin” and was purported to represent a convenient mechanism for the delivery of salicylic acid in the treatment of rheumatic diseases, menstrual pain, and fever.2 Approximately 40 years elapsed before Douthwaite and Lintott4 provided endoscopic evidence that aspirin could cause gastric mucosal damage. Numerous reports have corroborated this observation,5–8 and the introduction of more potent agents . . .

Gastrointestinal toxicity of nonsteroidal antiinflammatory drugs.

The intestinal epithelium is a single-cell layer that constitutes the largest and most important barrier against the external environment. It acts as a selectively permeable barrier, permitting the absorption of nutrients, electrolytes, and water while maintaining an effective defense against intraluminal toxins, antigens, and enteric flora. The epithelium maintains its selective barrier function through the formation of complex protein-protein networks that mechanically link adjacent cells and seal the intercellular space. The protein networks connecting epithelial cells form 3 adhesive complexes: desmosomes, adherens junctions, and tight junctions. These complexes consist of transmembrane proteins that interact extracellularly with adjacent cells and intracellularly with adaptor proteins that link to the cytoskeleton. Over the past decade, there has been increasing recognition of an association between disrupted intestinal barrier function and the development of autoimmune and inflammatory diseases. In this review we summarize the evolving understanding of the molecular composition and regulation of intestinal barrier function. We discuss the interactions between innate and adaptive immunity and intestinal epithelial barrier function, as well as the effect of exogenous factors on intestinal barrier function. Finally, we summarize clinical and experimental evidence demonstrating intestinal epithelial barrier dysfunction as a major factor contributing to the predisposition to inflammatory diseases, including food allergy, inflammatory bowel diseases, and celiac disease.

Intestinal barrier function: molecular regulation and disease pathogenesis.

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(09)60938-7.pdf

Peptic ulcer disease

Risks of bleeding peptic ulcer associated with individual non-steroidal anti-inflammatory drugs

Prophylactic aspirin and peptic ulcer bleeding

AIMS—To determine risk factors for peptic ulcer bleeding other than non-steroidal anti-inflammatory drugs (NSAIDs).
Methods—Data on possible antecedent risk factors obtained in a large case control study of 1121 patients admitted to hospitals in Glasgow, Newcastle, Nottingham, Oxford, and Portsmouth with bleeding peptic ulcers were compared with the same information obtained in 989 population controls. Data were analysed by logistic regression with the calculation of odds ratios (OR) and 95% confidence intervals (CI).
RESULTS—From a logistic regression model, oral anticoagulants (OR 7.8; 95% CI 2.8-21.5), previous peptic ulcer (3.8; 2.6-4.9), treatment for heart failure (5.9; 2.3-13.1), oral corticosteroid use (2.7; 1.3-4.5), treatment for diabetes (3.1; 1.2-4.3), and current smoking (1.6; 1.2-2.0) were all independent risk factors. No association was found with use of calcium channel antagonists. Odds ratios for concomitant NSAID usage were multiplicative with the exception of current smoking.
CONCLUSIONS—Some 45% of admissions for peptic ulcer bleeding in England and Wales in those aged 60 or more are calculated to be attributable to, or associated with, these accessory risk factors, which, together with those associated with aspirin or other NSAID use will account for over 80% of predisposing factors to ulcer bleeding.


Keywords: peptic ulcer; risk factors; anti-inflammatory drugs

https://gut.bmj.com/content/gutjnl/46/1/27.full.pdf

Peptic ulcer bleeding: accessory risk factors and interactions with non-steroidal anti-inflammatory drugs

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Risks of bleeding peptic ulcer associated with individual non-steroidal anti-inflammatory drugs

Prophylactic aspirin and peptic ulcer bleeding

Peptic ulcer bleeding: accessory risk factors and interactions with non-steroidal anti-inflammatory drugs