Most randomized controlled trials for psoriasis used placebo comparators despite the availability of effective treatments

Abstract

BackgroundThe availability of effective treatments for psoriasis raises ethical questions about the use of a placebo group in therapeutic trials. We evaluated the use of the placebo over time in such trials. MethodsFrom trials in a living Cochrane review and network meta-analysis for psoriasis, we included trials comparing a biologic to a placebo or other systemic treatment. First, we tested the changes in placebo rate from 2001 to 2019 by linear regression, then constructed networks for 2004–2019 and evaluated the contribution of the placebo to the network meta-analysis estimates per trial and per comparison. ResultsWe included 81 trials (36,774 patients). The placebo rate did not decrease significantly over time. The proportion contribution of trials with a placebo decreased from 100% in 2004 to 86% in 2008 and 75% in 2019. However, the proportion contribution of trials without a placebo remained low (from 0% in 2004 to 25% in 2019). ConclusionThe design of future psoriasis trials should be reviewed to improve the number of patients to be included in a placebo group.