Abstract
Randomized controlled trials are the principal means of establishing the efficacy of drugs. However pre-marketing trials are limited in size and duration and exclude high-risk populations. They have limited statistical power to detect rare but potentially serious adverse events in real-world patients. We summarize the principal methodological challenges in the reporting, analysis and interpretation of safety data in clinical trials using recent examples from systematic reviews. These challenges include the lack of an evidentiary gold standard, the limited statistical power of randomized controlled trials and resulting type 2 error, the lack of adequate ascertainment of adverse events and limited generalizability of trials that exclude high risk patients. We discuss potential solutions to these challenges. Evaluation of drug safety requires careful examination of data from heterogeneous sources. Meta-analyses of drug safety should include appropriate statistical methods and assess the optimal information size to avoid type 2 errors. They should evaluate outcome reporting biases and missing data to ensure reliable and accurate interpretation of findings. Regulatory and academic partnerships should be fostered to provide an independent and transparent evaluation of drug safety.
Highlights
Randomized controlled trials are primarily designed to provide reliable information on the efficacy of interventions [1]
The role of drug safety regulation is to protect patients from rare, severe adverse reactions; most efforts are directed at early detection and prevention of serious events such as that seen with thalidomide
This review summarizes the principal methodological challenges in the reporting, analysis and interpretation of safety data in clinical trials
Summary
Randomized controlled trials are primarily designed to provide reliable information on the efficacy of interventions [1]. They form the primary basis of regulatory approval for a drug in the US, which involves demonstrating evidence of efficacy and safety in two well-conducted studies With rare exceptions, these are generally interpreted as statistically significant data from two randomized clinical trials. A meta-analysis of 14 double-blind placebocontrolled randomized controlled trials reported a statistically significant increase in serious adverse cardiac events with varenicline [3] Another intensive postmarketing cohort study reported on the underlying mechanisms by which this cardiovascular hazard is mediated [5]. The apparent safety of omeprazole when used together in a trial with clopidogrel has been questioned because of the proprietary formulation used [30] In another example, a meta-analysis of 17 clinical trials reported a statistically significant increased risk of MI, stroke and CV death with inhaled anticholinergics (ipratropium bromide and tiotropium bromide) [7].
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