Regional differences in hip fracture risk in Turkey.

The aims of this study were to compare the incidence of hip fracture in different regions of Turkey and to investigate causes for potential differences. Hip fracture cases from two cities (Istanbul and Ankara) and three rural regions (Samsun, Erzurum and Diyarbakir) were compared with non-fractured controls from the same area with similar age and of the same sex. The risk of hip fracture was higher among persons living in rural areas than among persons living in urban areas, RR = 3.2 (p < 0.001) and 2.3 (p = 0.009) in men and women, respectively. Adjustment for differences in age and BMI between cases and controls did not substantially change these findings, RRadj = 2.7 (p < 0.001) and 2.1 (p = 0.036), neither did adjustment for exercise or differences in gonadal status in women. Education was the only adjustment factor that seemed to reduce differences between urban and rural areas, RRadj = 2.0 (p = 0.109) and 1.2 (p = 0.816). No difference in the risk of hip fracture could be detected between persons who migrated from rural to urban areas and persons born in urban areas. When restricting the analyses of differences between rural and urban areas to low-energy fractures, no difference in risk could be detected. When adjusting for differences in age and body mass index (BMI) the relative risks were RRadj = 0.8 (p = 0.873) and 1.2 (p = 0.852). The conclusion of these results is that the observed higher total risk of hip fracture in the rural areas of Turkey primarily can be explained by a larger proportion of high-energy fractures in the rural areas, whereas the risk of low-energy fractures seems to be similar.