Hip fractures in Norway 1999–2008: time trends in total incidence and second hip fracture rates. A NOREPOS study

Declining incidences of hip fractures are reported from western countries. Norway has among the highest rates in the world. The aim of this study was to investigate trends in total hip fracture rates in Norway between 1999 and 2008 and risk of second hip fractures. All hospitalizations given a hip fracture diagnosis code (International Classification of Diseases (ICD) 9 or ICD 10) (cervical, trochanteric or subtrochanteric) in Norwegian hospitals were retrieved with accompanying surgical procedure codes and additional diagnoses. A total of 93,123 hip fractures were identified between 1999 and 2008 in persons ≥50 years. Annual incidences of hip fractures were calculated and tested for trends. Rates of first and second hip fractures (2006–2008) were compared. The age-standardized total incidence of hip fracture decreased by 13.4 % (95 % confidence interval (CI): 11.0–15.6) in women and 4.8 % (95 % CI: 0.7, 8.7) in men. Age-adjusted rates of second hip fractures did not change in the observation period. In those with a prior hip fracture, the age-standardized risk of a subsequent hip fracture was 2.5-fold (95 % CI: 2.5, 2.6) in women, and 4.6-fold (95 % CI: 4.5, 4.7) in men. Total hip fracture rates declined in both genders during 1999–2008, whereas rates of second hip fractures did not change.