Reporting Bias in Randomized Controlled Trials of Homeopathy: A Critical Assessment and Re-Analysis of Published Work

Reporting bias is widespread in clinical trials, yet a 2022 assessment of reporting bias specifically in homeopathy claimed to show 'a concerning lack of scientific and ethical standards.' If true, decisive action is needed. The aim of this study was thus to assess the reliability of these published claims.

Critical assessment of the 2022 published data (N = 231 studies) was performed through in-depth literature/trial registry searching and systematic data extraction. Substantial inaccuracies were identified and corrected. Reporting bias in homeopathy was then re-analyzed (N = 181 studies) emphasizing trial registration, publication rates and primary outcome change.

Re-analysis of the corrected data showed that 93% of registered homeopathy trials are published; 60% of published trials are registered; 64% of registered trials were registered before trial completion; and 11% of prospectively registered and published trials had a primary outcome change. Compared to the published 2022 values (62%, 48%, 50% and 25% respectively), reporting bias in homeopathy is less common than claimed. Furthermore, 88% of homeopathy trials mentioned ethical approval, and 70% of journals publishing homeopathy trials comply with the International Committee of Medical Journal Editors' recommendations.

This re-analysis shows that levels of reporting bias in homeopathy trials are at least comparable to those in the wider medical literature where half of registered trials remain unpublished and primary outcome change occurs in ~30%. Researchers in all medical disciplines, including homeopathy, should continue to strive towards the highest level of research standards, following international recommendations for registration and publication of all trials.