The new studies suggest that the review was not based on a comparative analysis and is unjustified because of the heterogeneity of trials and lack of sensitivity analysis.
"The review gave no indication of which trials were analysed nor of the various vital assumptions made about the data. This is not usual scientific practice. If we presume that homeopathy works for some conditions but not others, or change the definition of a 'larger trial', the conclusions change. This indicates a fundamental weakness in the conclusions: they are not reliable", said George Lewith, Professor of Health Research at Southampton University
In August 2005, The Lancet published an editorial entitled 'The End of Homeopathy', prompted by a review comparing clinical trials of homeopathy with trials of conventional medicine.
The claim that homeopathic medicines are just placebo was based on 6 clinical trials of conventional medicine and 8 studies of homeopathy but did not reveal the identity of these trials.
The review was criticised for its opacity as it gave no indication of which trials were analysed or the various assumptions made about the data.
Sufficient detail to enable a reconstruction was eventually provided and the two new studies are based on such a reconstruction and challenge the Lancet review.
These two studies show that analysis of all high quality trials of homeopathy yields a positive conclusion.
The 8 larger higher quality trials of homeopathy were all for different conditions. Homeopathy works for some of these but not others, implying that homeopathy is not placebo.
The comparison with conventional medicine was meaningless. Doubts remain about the opaque, unpublished criteria used in the review, including the definition of 'higher quality'.
This reconstruction casts serious doubts on the Lancet review, showing that it was based on a series of hidden judgments unfavourable to homeopathy.
An open assessment of the current evidence suggests that homeopathy is probably effective for a number of conditions including allergies, upper respiratory tract infections and 'flu, but more research is desperately needed.
Prof Matthias Egger of the Department of Social and Preventive Medicine at the University of Berne, who led The Lancet trial, declined to comment on these findings.