The epidemiologic transition and morbidity.

In essays about the theory of epidemiologic transition, Abdel Omran has argued that demographic change in the last century occurred in stages that can be characterized by their leading causes of death. The transition consists of a change in leading causes from infectious to degenerative and man-made diseases. In that version of the theory, the death rate is held to approximate the sickness rate. This essay identifies an epidemiologic transition in morbidity, using insurance records and health surveys to assess the morbidity trend. Two morbidity rates -incidence and prevalence- are distinguished. Each describes a trend independent from the mortality trend. While the risk of death declined sharply after 1870 in Britain, the age-specific incidence of disease and injury remained approximately level and the age-specific of duration increased. These independent trends are explained in part by ways the mortality decline affected the composition of the population. And they in turn affect interpretation of the mortality decline and the epidemiologic transition by suggesting that a key change occurred in the outeome of maladies. Sicknesses were more prolonged, but more people recovered.