Preventive medicine: the objectives

The objectives of preventive medicine are to prolong life and to reduce disability. Improvements in the standard of living and in medical treatment and specific measures to reduce the incidence of disease have greatly reduced mortality over the last century. The distribution of deaths by age has altered dramatically and, at current rates, the great majority of deaths will occur at 80-85 years of age. Improvement has continued to the present and is still not slackening. It seems unlikely that many deaths can be postponed much beyond 100 years, but a realistic objective would be to raise the median age of death to about 90 years. This would require a substantial reduction in mortality from three groups of diseases that are now the main cause of life lost under 85 years of age: neoplasms, ischaemic heart disease, and other vascular disease. Watch will also need to be kept on diseases that threaten to become more common, so that we can abort new epidemics. Whether a reduction in age-specific mortality rates will also bring a reduction in the prevalence of disability at each age is unclear. Some believe that it will, so that if we concentrate on reducing age-specific mortality, everyone will eventually survive to such an age that failure of homeostasis will bring about a sudden collapse. Others suspect that postponing death will lead to a greater prevalence of pre-terminal disability, due to the prevalence of diseases that are largely independent of or even inversely related to mortality. The objectives of preventive medicine are realizable only in so far as they are perceived to be desirable by society. The perception of what is desirable depends not only on objective quantification, but also on a variety of subjective assessments. Preventive medicine must, therefore, allow for the factors that produce these assessments and educate the public to give them appropriate weight.