BMJ. 1991 Feb; 302(6772): 316-23.

Clinical trials of homoeopathy.

Kleijnen J, Knipschild P, ter Riet G.

Department of Epidemiology and Health Care Research, University of Limburg, Maastricht, The Netherlands.

OBJECTIVE--To establish whether there is evidence of the efficacy of homoeopathy from controlled trials in humans. DESIGN--Criteria based meta-analysis. Assessment of the methodological quality of 107 controlled trials in 96 published reports found after an extensive search. Trials were scored using a list of predefined criteria of good methodology, and the outcome of the trials was interpreted in relation to their quality. SETTING--Controlled trials published world wide. MAIN OUTCOME MEASURES--Results of the trials with the best methodological quality. Trials of classical homoeopathy and several modern varieties were considered separately. RESULTS--In 14 trials some form of classical homoeopathy was tested and in 58 trials the same single homoeopathic treatment was given to patients with comparable conventional diagnosis. Combinations of several homoeopathic treatments were tested in 26 trials; isopathy was tested in nine trials. Most trials seemed to be of very low quality, but there were many exceptions. The results showed a positive trend regardless of the quality of the trial or the variety of homeopathy used. Overall, of the 105 trials with interpretable results, 81 trials indicated positive results whereas in 24 trials no positive effects of homoeopathy were found. The results of the review may be complicated by publication bias, especially in such a controversial subject as homoeopathy. CONCLUSIONS--At the moment the evidence of clinical trials is positive but not sufficient to draw definitive conclusions because most trials are of low methodological quality and because of the unknown role of publication bias. This indicates that there is a legitimate case for further evaluation of homoeopathy, but only by means of well performed trials.