A German team of researchers has recently concluded that placebo effects in classical homeopathy did not appear to be larger than placebo effects in conventional medicine.
Critics argue that homeopathy is something like a super-placebo, saying that homeopathy has the ability to evoke large nonspecific health effects. It is said that the long interview carried out by an empathetic practitioner during diagnosis may explain why people report improvements in their health.
The research team therefore investigated whether contextual effects in classical homeopathy are higher than in conventional medicine. For this they compared the changes in the placebo groups of RCTs from classical homeopathy and matching conventional trials.
The authors performed a systematic literature analysis on placebo-controlled doubleblind RCTs on classical homeopathy. Each trial was matched to three placebo-controlled double-blind RCTs from conventional medicine (mainly pharmacological interventions) involving the same diagnosis. Matching criteria included severity of complaints, choice of outcome parameter, and treatment duration. Outcome was measured as the percentage change of symptom scores from baseline to end of treatment in the placebo group. 35 RCTs on classical homeopathy were identified. 10 were excluded because no relevant data could be extracted, or less than three matching conventional trials could be located.
The results showed that in 13 matched sets the placebo effect in the homeopathic trials was larger than the average placebo effect of the conventional trials, in 12 matched sets it was lower (P = 0.39). Additionally, no subgroup analysis yielded any significant difference.
The authors conclude that placebo effects in placebo-controlled double-blind clinical trials (RCTs) on classical homeopathy did not appear to be larger than placebo effects in conventional medicine.
Reference : Nuhn T, Lüdtke R, Geraedts M (2010). Placebo effect sizes in homeopathic compared to conventional drugs – a systematic review of randomised controlled trials. Homeopathy, 99: 76–82.
PubMed abstract available : http://www.ncbi.nlm.nih.gov/pubmed/20129180