Time trends of age-adjusted incidence rates of first hip fractures: A register-based study among older people in Viborg County, Denmark, 1987-1997

A retrospective cohort study was performed to investigate if incidence rates of first hip fractures are changing in a Danish county. Study material was obtained from an excerpt from a computerized national health register and covers the period 1987-1997. First hip fractures were identified through a search 10 years back from the date of admission. To assess the 20-year trend, 1978 data were included. The study period saw inclusion of 3,036 first (1987-1997) and 122 first and recurrent (1978) hip fracture patients aged 50 years and older. Data were analyzed using weighted regression analysis. Age-adjusted first hip fracture incidence rates increased significantly (P < 0.001) for women, men, and pertrochanteric fractures. The rate of increase was 18 [95% confidence interval (CI), 12-25], 8 (95% CI, 4-12), and 10 (95% CI, 7-12) per 100,000 per year for women, men, and pertrochanteric fractures, respectively. The age-adjusted rate for both genders combined was 425 per 100,000 in 1997 (95% CI, 380-470). The incidence of cervical fractures was stable. If the rates of 1978 were included in the analysis, the cervical hip fractures also increased (P < 0.001). The weighted average of female-male ratio was a stable 2.6 (95% CI, 2.4-2.8). Cervical-pertrochanteric ratio dropped to 1.2:1 (P < 0.001). Mean age at admission rose from 78.9 to 80.8 years. In conclusion, the results provided support for an increasing incidence of first hip fractures, even when aging of the population was accounted for.