[Epidemiology of osteoporosis].

Osteoporosis is a systemic disease of the skeleton characterized by decreased bone mass and a disturbed microarchitecture of the bone. Its consequences is an increase in fracture risk. In women, the risk of experiencing an osteoporotic fracture once in life is twice as high (30-40%) as in men. In a model using population-based data, it is estimated that 54% of 50-year-old women present an osteoporotic fracture once in their remaining life. Typical osteoporotic fractures involve vertebral bodies, the proximal femur and the forearm. The number of fractures caused by osteoporosis is steadily increasing, due to greater life expectancy in particular. In addition, there is a secular increase in the incidence of fractures. In Switzerland, the number of fractures of the hip per year increased from 5,500 in 1980 to 9,800 in 1990 (VESKA data). The consequences of these fractures for the patients and their life quality and the direct and indirect effects on society are generally underestimated. Mortality and morbidity are both increased in comparison with unfractured persons of the same age. One of the most serious consequences of hip fractures is the loss of functional independence in the elderly; 10% of patients lose their functional independence after such fractures, and about 10% need to be placed in homes. Fractures of the waist lead to hospitalization in about 70% of patients aged over 85, and in many patients with forearm fractures algodystrophy occurs. Hip fractures are responsible for about 175,000 days in hospital per year for all Switzerland. Applied to all fractures caused by osteoporosis, this number may be much higher. Lack of epidemiological data, insufficient methods of investigation and the symptomless and silent development of osteoporosis in its beginnings have in many respects led to severe underestimation of this disease in the past. The extension of this growing worldwide health problem has only recently become apparent in Switzerland, essentially because of increasing life expectancy. The frequency of hip fractures is well documented in Switzerland and comparable with that in the US. It justifies in itself the development of a strategy for prevention and treatment. But because osteoporosis is a systemic disease of the skeleton, additional Swiss data on fractures other than that of the hip, such as vertebral and forearm fractures, would be of great interest, especially in the sector of ambulatory medicine.