Incidence, timing and impact of comorbidity on second hip fracture: a population-based study

To quantify the incidence and timing of second hip fracture, and to evaluate the relative impact of comorbidities on risk of second hip fracture.

Hospitalization records for individuals aged ≥65, admitted to a New South Wales hospital for fall-related hip fracture between 1 January 2005 and 31 December 2009 were linked. Comorbidities were identified from the records using a 1-year look-back period. To calculate second hip fracture rates, individuals were followed until death, fracture or end of study period (31 December 2012). Time-dependent competing-risk hazards regression was used to assess the relative contribution of each comorbidity to fracture risk, adjusting for age and sex.

Of the 24 500 individuals who sustained at least one hip fracture, 2.9% experienced a second within a year, 6.1% within 3 years and 9.4% within 8 years. Malnutrition/cachexia (hazard ratio (HR): 2.47; 99.9% confidence interval (CI): 1.87-3.26), dementia (HR: 2.15; 99.9% CI: 1.80-2.57), congestive heart failure (HR: 1.62; 99.9% CI: 1.30-2.04), Parkinson's disease (HR: 1.51; 99.9% CI: 1.08-2.10), cerebrovascular disease (HR: 1.41; 99.9% CI: 1.06-1.89) and osteoporosis (HR: 1.36; 99.9% CI: 1.11-1.67) were associated with increased risk of second hip fracture within 3 years. Mortality was high; with 26% of individuals dying within a year, 44.9% within 3 years and 70.2% within 8 years.

One in 11 older individuals with an initial hip fracture sustained a second hip fracture. While the priority is to prevent the first hip fracture, those that have sustained a hip fracture should be seen as a high risk population and be targeted for future falls and fracture prevention strategies.