Differences in risk factor patterns between cervical and trochanteric hip fractures

The two types of hip fracture - cervical and trochanteric femoral fractures - are generally considered together in etiologic studies. However, women with a trochanteric fracture may be more osteoporotic than those with cervical hip fractures, and have higher postfracture mortality. To explore differences in risk factor patterns between the two types of hip fracture we used data from a large population-based case-control study in Swedish women, 50-81 years of age. Data were collected by questionnaire, to which more than 80% of subjects responded. Of the cases included, 811 had had a cervical fracture and 483 a trochanteric fracture during the study period; these cases were compared with 3312 randomly selected controls. Height and hormonal factors appeared to affect the risk of the two types of hip fracture differently. For every 5 cm of current height, women with a cervical fracture had an adjusted odds ratio (OR) of 1.23 (95% CI 1.15-1.32) compared with an OR of 1.06 (95% CI 0.97-1.15) for women with trochanteric fractures. Later menopausal age was protective for trochanteric fractures (OR 0.95, 95% CI 0.91-0.99 per 2 years) but no such association was found for cervical fractures. Compared with never smokers, current smokers had an OR of 1.48 (95% CI 1.12-1.95) for trochanteric fractures and 1.22 (95% CI 0.98-1.52) for cervical fractures. Current hormone replacement therapy was similarly protective for both fracture types, but former use substantially reduced risk only for trochanteric fractures: OR 0.55 (95% CI 0.33-0.92) compared with 1.00 (95% CI 0.71-1.39) for cervical fractures. These risk factor patterns suggest etiologic differences between the fracture types which have to be considered when planning preventing interventions.