Hip fracture mortality and morbidity in Switzerland and Japan: a cross-cultural comparison.

Based on national mortality data, the frequency of hip fractures in elderly people was compared between Switzerland and Japan. Age-adjusted annual incidence rates per 100,000 population estimated for Swiss persons over 60 years were around 150 and 200 in males and around 450 in females, while for the Japanese they were only 132 in males and 285 in females. Age-adjusted death rates from hip fracture for the Swiss over 60 were 20.0 in males and 28.9 in females, while for the Japanese they were only 1.6 in males and 2.7 in females. The inclination of the age-dependent slope in hip fracture mortality rates was substantially the same in both countries, but there was a "lag time" of approximately 10 years in Japan. Remarkably, the proportion of deaths due to falls among all accidental deaths was several times greater in both sexes for the Swiss than for the Japanese. This differential might be an important underlying reason for the observed difference between death rates of hip fracture in Switzerland and Japan. Other known behavioral risk factors for hip fracture such as diet, exercise, estrogen use etc. are unlikely to explain the observed difference in hip fracture mortality and morbidity between Switzerland and Japan. However, given the doubts on the reliability and thus comparability of the available data on mortality and morbidity, the present findings should be regarded as preliminary. In conclusion, we believe that the unexplained and large difference in the burden of hip fracture between Switzerland and Japan merits further studies, including new aetiological hypotheses.