The epidemiology of osteoporosis. A selective overview.

The epidemiology of osteoporosis is usually studied in its manifestations and not as a condition as such because it is difficult to measure, and measurements are difficult to interpret. Is osteoporosis not only a condition with less bone, but also a process implying reduction of bone or both? Beyond doubt, these manifestations by fractures of various types constitute a major health problem in terms of morbidity, mortality, socio-economy, and quality of life. Furthermore, an increasing incidence of hip fractures that remain after age standardization have occurred e.g. in the Scandinavian countries. Little is known about fractures other than hip fractures and Colles's fractures. There is some evidence that ethnic and/or racial differences in the occurrence of osteoporosis and its manifestations might be 20-fold. The web of explanations for these differences, be it nature or nurture, is insufficiently known although some risk factors are identified. The pattern of prevention of osteoporosis includes several important issues. Does an increased bone mass or a reduction of the speed of loss of bone mass in fact mean a reduction in the number of fractures? Which are the prospects of prevention within an epidemiological framework and how can these possibilities be envisaged on a time scale?