Randomized controlled trials of antidepressants: clinically and scientifically irrelevant

Withdrawal effects confounding in clinical trials: another sign of a needed paradigm shift in psychopharmacology research

Randomized controlled trials' ability to produce evidence useful for people to decide whether to take, continue taking, or stop taking psychotropic drugs has been intensely critiqued, along with the trials' commercial, ideological, and regulatory contexts. This article applies the critique to the topic of withdrawal effects confounding the outcomes of relapse-prevention trials where prescribed psychotropic drugs are discontinued. Until recently, the complexity and reach of withdrawal and post-withdrawal effects were neglected by mainstream psychiatry, but not by lay users of prescribed psychotropics. This article discusses withdrawal effects as part of the pharmacology of psychotropic drugs but shaped by psychosocial factors, and possibly shaping the presentation of psychological distress generally. It outlines biases and misconceptions in assumptions, design, and reporting of general efficacy trials and findings from a recent review of 80 discontinuation trials. In theory, relapse-prevention trials are tautological and exaggerate efficacy. In publications, they pay little attention to the central feature of their design, favor abrupt or rapid discontinuations, do not attend to environmental factors, and provide insufficient data to allow re-analyses. Thus, relapse-prevention RCTs likely confound the detection of their main outcome of interest: "relapse." Using slower tapers, active placebo controls, and specific covariates in analyses would reduce the risk of withdrawal confounding, and better reporting would reduce the opaqueness of trials. The crisis in psychopharmacology is fueled partly by the disconnect between claims of therapeutic efficacy from so-called best-evidence methods despite unchanging population-level indicators of psychiatric sickness. Only by "stacking the deck" against trial sponsors' hoped-for outcomes can psychopharmacology trials regain scientific credibility.

Active placebo control groups of pharmacological interventions were rarely used but merited serious consideration: a methodological overview

OBJECTIVES

Active placebos are control interventions that mimic the side effects of the experimental interventions in randomized trials and are sometimes used to reduce the risk of unblinding. We wanted to assess how often randomized clinical drug trials use active placebo control groups; to provide a catalog, and a characterization, of such trials; and to analyze methodological arguments for and against the use of active placebo.

STUDY DESIGN AND SETTING

An overview consisting of three thematically linked substudies. In an observational substudy, we assessed the prevalence of active placebo groups based on a random sample of 200 PubMed indexed placebo-controlled randomized drug trials published in October 2013. In a systematic review, we identified and characterized trials with active placebo control groups irrespective of publication time. In a third substudy, we reviewed publications with substantial methodological comments on active placebo groups (searches in PubMed, The Cochrane Library, Google Scholar, and HighWirePress).

RESULTS

The prevalence of trials with active placebo groups published in 2013 was 1 out of 200 (95% confidence interval: 0-2), 0.5% (0-1%). We identified and characterized 89 randomized trials (published 1961-2014) using active placebos, for example, antihistamines, anticholinergic drugs, and sedatives. Such trials typically involved a crossover design, the experimental intervention had noticeable side effects, and the outcomes were patient-reported. The use of active placebos was clustered in specific research settings and did not appear to reflect consistently the side effect profile of the experimental intervention, for example, selective serotonin reuptake inhibitors were compared with active placebos in pain trials but not in depression trials. We identified and analyzed 25 methods publications with substantial comments. The main argument for active placebo was to reduce risk of unblinding; the main argument against was the risk of unintended therapeutic effect.

CONCLUSION

Pharmacological active placebo control interventions are rarely used in randomized clinical trials, but they constitute a methodological tool which merits serious consideration. We suggest that active placebos are used more often in trials of drugs with noticeable side effects, especially in situations where the expected therapeutic effects are modest and the risk of bias due to unblinding is high.