No evidence exists to justify the use of homoeopathy in the NHS, an in-depth analysis of published data has concluded.
The study, carried out by the NHS Centre for Reviews and Dissemination, based at York University, reviewed data from over 200 randomised clinical trials of homoeopathy in a variety of conditions.
It concluded that not only was there little evidence to support the efficacy of homoeopathy, but the data that did exist were of poor quality and came from trials that were often deeply flawed.
Common problems included under-powered studies, failure to analyse by intention to treat, and failure to use allocation concealment. Some of the published systematic reviews are criticised for pooling clinically heterogeneous data.
"The evidence base for homeopathy needs to be interpreted with caution," stated the review. "All conclusions about effectiveness should be considered together with the methodological inadequacies of the primary studies and some of the systematic reviews. Many of the areas that have been researched are not representative of the condition that homeopathic practitioners usually treat."
The review, published in the same week as a study from Southampton found that homoeopathic immunotherapy was not an effective treatment for patients with asthma (2 March, p 520), counselled against increasing NHS provision of homoeopathic remedies until more convincing evidence emerges.
It cited a number of controversies surrounding the scientific validation of the current data.
These include the difficulty in providing a placebo comparison to homoeopathic treatments that have already been diluted to such an extent that not a single molecule of the starting substance remains.
"Given the absence of a plausible mechanism of action, it has been argued that the existing evidence base represents little more than a series of placebo versus placebo trials," stated the review.
It also pointed out the problem of reproducing homoeopathy's highly individualised real life practice, where two patients showing similar symptoms may be offered entirely different treatments.
Despite these longstanding doubts, however, homoeopathic remedies remain widely used in the NHS.
There are five homeopathic hospitals and it has been estimated that 39% of GP practices provide access to some form of complementary therapy for their NHS patients. Homoeopathy accounts for about half of these referrals. A BBC telephone survey in 1999 suggested that 470 000 people take homoeopathic remedies in the United Kingdom each year.
The review stops short of recommending that this NHS provision of homoeopathy should be halted. However, it urges strongly against any increase in its provision.
"There is currently insufficient evidence of effectiveness to either recommend homeopathy as a treatment for any particular condition or warrant significant changes in the current provision of homeopathy," it concluded.
The homoeopathy report is available at http://www.york.ac.uk/inst/crdwww.york.ac.uk/inst/crd