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Evidence-Based Medicine Is A Questionable Basis For Allocating National Health Service Resources

Evidence-based medicine, the supposedly objective assessment of the outcomes of medical interventions, is increasingly popular in the NHS. The hope is that it will offer opportunities for controlling the escalating costs of health care. But according to David Whynes, writing in the latest issue of the Economic Journal, evidence-based medicine could have highly undesirable effects on the allocation of NHS resources. What''s more, he points out, there is a certain irony about the current enthusiasm for evidence, given that the massive recent restructuring of the UK health care system took place in the complete absence of any officially sanctioned evaluation.

Whynes notes that health care is expensive and is becoming increasingly so. Estimates for 1995 indicate that the OECD countries devoted an average of 10.4% of their GDPs to public and private health care spending, more than double the 1960 proportion of 4.7%. On the outcome side, all OECD countries have consistently experienced reductions in infant mortality and increases in average life expectancy since the 1960s.

What remains far from clear is whether these gains can be attributed to increased health care spending alone rather than to improvements in living standards or changes in lifestyle. The question at issue is whether each of the vast and ever increasing number of different medical interventions currently being undertaken is actually effective in improving the health of patients.

Uncertainty is endemic in medicine practice, some of which arises because the symptoms and needs of each individual patient are in some degree unique. Beyond this, however, the fact remains that the effectiveness of only a surprisingly small proportion of the thousands of existing medical interventions is actually supported by robust experimental evidence. Nevertheless, there has been an emergence of interest in the objective assessment of the
outcomes of medical interventions. From the economic point of view, it is hoped that evidence-based medicine will offer opportunities for controlling the escalating costs of health care. The identification of ineffective treatments in general will permit the elimination of unnecessary expenditures. Moreover, evidence should permit health authorities to discriminate between high cost providers that are simply inefficient and those that are genuinely more cost-effective. If ''better'' evidence of effectiveness in the future offers the prospect of reducing uncertainty
within the practice of medicine, the corollary is presumably that ''better'' decisions will result. But studies suggest that practical responses to medical evidence are variable.

Individual physicians might legitimately disagree about whether the outcomes established by medical trials are actually the most appropriate outcomes for their own patients. Difficulties in agreeing on an initial diagnosis provide further scope for genuine disagreement about appropriate therapies. On the basis of evidence collection, uncertainty can be reduced though such a reduction comes at a price. For a health care system like the NHS, where budgets are fixed, the opportunity cost of obtaining data to refine the certainties surrounding the effectiveness of one intervention will be the evaluation of therapies as yet poorly evaluated or even restriction on the use of other interventions, possibly including those with proven efficacy.

In terms of patterns of resource allocation, much depends on how evidence is used. If we accept that the majority of current medical interventions remain to be evaluated for effectiveness, then the potential economic implications of the possible responses to evidence are enormous. Some commentators are extremely nervous about the current popularity of evidence-based medicine, fearing that it might legitimate the rationing of NHS resources to only those interventions where positive effectiveness has been demonstrated. Such a strategy would introduce considerable bias into resource allocation. On the other hand, allowing the NHS to undertake treatments in all cases where no adverse evidence exists could legitimate even greater expense than is currently undertaken. There is a certain irony about the current enthusiasm for evidence in the NHS, given that the massive recent restructuring of the UK health care system took place in the complete absence of any officially sanctioned evaluation. The current official position appears to be that evidence is important enough to inform any one resource allocation decision within the health service but not sufficiently important to inform a decision about resource allocation for the health service as a whole.

''Towards an Evidence-based National Health Service?'' by David K. Whynes is published in the November 1996 issue of the Economic Journal. Whynes is at the University of Nottingham. His work on the NHS forms part of the Economic and Social Research Council''s research programme on Economics Beliefs and Behaviour.