Intended for healthcare professionals


The costs of prevention

BMJ 1995; 311 doi: (Published 09 December 1995) Cite this as: BMJ 1995;311:1520
  1. John Cairns
  1. Director Health Economics Research Unit, Aberdeen AB9 2ZD

    Not necessarily better than cure

    To many doctors it seems fundamentally wrong to let people become ill before intervening when it would be possible to take effective action at an earlier stage—for example, by screening. Delayed intervention results in avoidable suffering and possibly a much poorer prognosis. People are also willing to believe that screening is a good investment, whereby costs are incurred now to avoid greater costs in the future. This faith in early action is part of folk wisdom, captured in aphorisms such as “a stitch in time saves nine.” In short, there is a widely held view that prevention is better than cure.

    If women aged 65-69 are not routinely screened for breast cancer, or are screened every three years rather than every two years, some will not receive care that would benefit them. However, the view that it is wrong not to benefit a particular group of patients when it is possible is based on too narrow a perspective. If the health care system is to serve the greater good of the population then resources must be directed to where they will be most highly valued. In economists' jargon, consideration must be given to the opportunity cost of any given use of resources. It is possible that a greater gain in health could be achieved by directing the resources elsewhere.

    The underlying assumption is that there are areas where additional expenditure would generate net benefits. But the answer is not simply to spend more. The increasing numbers of elderly citizens, rising expectations of health care, and advances in technology (which on balance tend not to reduce costs) suggest that substantial increases in spending would be required before we reached the point at which further spending brought no additional benefit. Even if it were possible to approach this point by feasible increases in spending, it would not be appropriate to do so unless the potential for health benefits from relieving poverty, improving education, and housing conditions were also exhausted. Opportunity cost will not go away.

    We need evidence if we are to argue that prevention can be justified on economic grounds. Part of the evidence on the costs and benefits of screening compared with those of not screening concerns the effectiveness of screening in improving both mortality and quality of life. Quality of life is likely to be influenced not only by treatment but also by the reassurance or anxiety generated by screening. We also need detailed information on the differences in use of resources between those screened and those not screened.1 It is generally necessary to distinguish between the costs of treating cancers detected by screening and those detected without.2 Any future savings in the costs of detection and treatment must be compared with the costs of screening. These are not simply the costs of the screening test but also the costs of such things as additional recruitment of patients and follow up of those with positive results.

    The position is further complicated by the timing of the use of resources. Costs incurred further in the future are generally valued less highly than those incurred in the near future. This is not simply myopia: it is another instance of opportunity cost. If current consumption is reduced in favour of greater investment then more resources will be available for consumption in the future. The opportunity cost of higher current health spending is that less money will be available for future expenditure and health benefits will be forgone as a consequence. The impact of such discounting strategies on the evaluation of screening is important since the typical screening programme involves a stream of costs starting now and stretching away into the future. The benefits in terms of illness or costs avoided do not occur immediately, and the difference in timing can be substantial.3

    Extensions to national breast screening programmes or any other forms of screening should not take place simply because some patients have a capacity to benefit from the activity. In an environment of scarce resources such decisions should be informed by an evaluation of the costs and benefits relative to those available from other interventions. Decisions on spending on prevention should not be taken in isolation from other decisions on how to allocate health care resources. Prevention is not necessarily better than cure.


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