Hip fractures in Nordic cities: difference in incidence.

All new hip fractures referred to hospital in 1989 were recorded in seven urban populations from Denmark, Finland, Norway and Sweden. The total population at risk (50 years and older) was 588,427, and 4075 fractures were observed (76.5% women). In all cities an age-dependent increase in incidence was found, and the female incidence was highest. When comparing the incidence rates after direct standardization, significant differences in hip fracture incidence were found between the cities for both women and men. The standardized relative rates seemed to decrease when moving south and east with the lowest rates found in Tampere, Finland. This indicates that factors which differ even between urban populations within a restricted geographical region may have an important impact on hip fracture incidence.