Prevention is considered a good thing to aspire to: preventing a disease occurring in the first place is clearly preferable to treating it once it has developed. By adopting this approach, surely we must be preventing suffering and death and prolonging life? For an individual who is certain to develop a serious disease in the future, taking effective preventive measures now definitely seems worthwhile. In some cases, however, a disease may get better spontaneously without any treatment, may take a long time to develop or never cause serious problems during the lifetime of the affected individual. Taking preventive measures in these circumstances will not benefit the individual concerned and may cause harm, inconvenience or expense if those measures have side effects or involve lifestyle changes, taking long-term medication or regular tests such as radiographs.
Provided there is full information available on the potential benefits and risks of the preventive measures proposed, individuals can decide for themselves whether to follow them or take the risk of developing the disease. The balance of risks and benefits, however, is different for prevention compared with treatment for symptomatic disease; the benefit occurs in the future, while risks associated with the preventive measure occur now (e.g. taking antihypertensive medication to prevent strokes). At a population level, it may be necessary to apply preventive measures to many people, some of whom would never develop the disease in question, in order to prevent a few people dying or getting serious disease (e.g. compulsory wearing of car seat belts). This prevention paradox