Evidence-based medicine is a worthy objective. According to the Oxford-based Centre for Evidence Based Medicine, “Evidence-based medicine is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients. The practice of evidence-based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research.”

The present campaign against homeopathy and other complementary therapies makes extensive use of these aims to justify calls for these therapies’ exclusion from the NHS on the grounds that there is “no evidence” for their efficacy. I’ve gone into the evidence question in relation to homeopathy in other posts. This one looks at the evidence base for biomedical treatment. After all, if biomedical treatment is to be so clearly preferred over the complementary therapies which presently lack the robust evidence base being demanded, then one would assume that biomedical treatments have a clear advantage here.

One would assume wrongly.

This from BMJ Clinical Evidence:

What proportion of commonly used treatments are supported by good evidence, what proportion should not be used or used only with caution, and how big are the gaps in our knowledge? Of around 2500 treatments covered 13% are rated as beneficial, 23% likely to be beneficial, 8% as trade off between benefits and harms, 6% unlikely to be beneficial, 4% likely to be ineffective or harmful, and 46%, the largest proportion, as unknown effectiveness (see figure 1). Dividing treatments into categories is never easy hence our reliance on our large team of experienced information specialists, editors, peer reviewers and expert authors. Categorisation always involves a degree of subjective judgement and is sometimes controversial. We do it because users tell us it is helpful, but judged by its own rules the categorisation is certainly of unknown effectiveness and may well have trade offs between benefits and harms. However, the figures above suggest that the research community has a large task ahead and that most decisions about treatments still rest on the individual judgements of clinicians and patients.

Clinical effectiveness

So let’s get this straight. Just 13% of the 2,500 treatments assessed — around 325 treatments — have been shown to have clear benefit. A further 23% are “likely to be beneficial”. The remainder, a staggering 64%, have either too many harmful side effects to be of clear benefit, are just plain ineffective and/or harmful, or have unknown effectiveness.

Yet so many of these drugs are presently being prescribed to the population of the United Kingdom that not only is the NHS close to bankruptcy, but traces of them are even showing up in rivers and drinking water supplies, including cytotoxic chemotherapy drugs which, according to figures publicised in 2003 by GlaxoSmithKline’s Allen Roses, have a response rate of only 25%. Further, for those that do respond to the therapy, a 2004 study concluded that “the overall contribution of curative and adjuvant cytotoxic chemotherapy to 5-year survival in adults was estimated to be 2.3% in Australia and 2.1% in the USA.” The authors went on to say “it is clear that cytotoxic chemotherapy only makes a minor contribution to cancer survival. To justify the continued funding and availability of drugs used in cytotoxic chemotherapy, a rigorous evaluation of the cost-effectiveness and impact on quality of life is urgently required.”

In the context of these figures, the present campaign against complementary therapies seems completely indefensible. Until biomedical treatments can provide robust evidence that their continued use is justified in terms of the benefit they provide to patients, then they too should be dropped from the NHS. And perhaps some of the enormous savings this would achieve could be spent on funding a better evidence base for complementary therapies …