Ten-year risk of second hip fracture. A NOREPOS study

Abstract

Background: Second hip fracture risk is elevated after the first, however whether risk differs with age, by sex or over time is not well known.

Objective: To examine the risk of second hip fracture by sex, age and time after first hip fracture.

Design: Data on all hip fractures in subjects 50 years and older and treated in Norwegian hospitals during 1999-2008 were retrieved. Surgical procedure codes and additional diagnosis codes were used to define incident fractures. Survival analyses with and without adjustment for competing risk of death were used to estimate the risk of second hip fracture.

Results: Among the 81,867 persons who sustained a first hip fracture, 6161 women and 1782 men suffered a second hip fracture during follow-up. The overall age-adjusted hazard ratio (HR) of a second hip fracture did not differ between the sexes (women versus men, HR=1.03; 95% confidence interval (CI): 0.98-1.09). Taking competing risk of death into account, the corresponding age-adjusted HR of a second hip fracture was 1.40 (95% CI: 1.33-1.47) in women compared to men. The greater risk in women was due to a higher mortality in men. Based on competing risk analyses, we estimate that 15% of women and 11% of men will have suffered a second hip fracture within 10 years after the first hip fracture. The ten-year cumulative incidence was above 10% in all age-groups, except in men 90 years and older.

Conclusion: Fracture preventive strategies have a large potential in both women and men who suffer their first hip fracture due to the high risk of another hip fracture.