Older persons who have suffered a hip fracture (HFx) are at increased risk of subsequent hip fractures. The cumulative incidence of a second hip fracture (SHFx) has been estimated in 8.4%; however, no studies have been carried out in our country, and the information on risk markers of SHFx is limited. The aim of this study was to estimate the incidence, explore trends, and examine predictors of SHFx in a suburban population of Spain. An observational longitudinal retrospective study was performed in a universal health coverage setting (Alcorcón, 1999-2011). Data were obtained from the area hospital discharge database. Annual incidence of HFx was estimated over 100,000 population (general and persons with HFx), and median time to SHFx by Kaplan-Meier tables. Cox regression was used for the analysis of association between SHFx and baseline predictors, measured by hazard ratio (HR). Among the 3430 patients who suffered a first HFx in the study period, 255 (7.4%) experienced a SHFx (4.5% of men and 8.5% of women). Median time between the first and second HFx was 3.7 years (SD 3.2). Annual incidence of HFx in population over 45 was 290.5 per 100,000 inhabitants (131.03 in men and 433.11 in women). Annual incidence of SHFx among persons with a HFx was 956.7 per 100,000 (1052.1 in women and 595.5 in men). There was a decline trend along the study period with an annual reduction of 10.4% (95% CI 7.7-13.0%; p < 0.001) in both sexes. The following associations were found: female sex (HR 1.41, 95% CI 0.97-2.02), age (HR 1.03, 95% CI 1.01-1.04), living in a nursing house (HR 1.46, 95% CI 1.10-1.94), and moderate to severe liver disease (HR 4.96, 95% CI 1.23-20.06). In our environment the occurrence of a SHFx is 7.4%, three-fold risk compared to no previous HFx. Being woman, elderly, living in a nursing home, and having severe to moderate liver disease may be important predictors of a SHFx. There seems to be adequate time between the first and the SHFx for interventions that may reduce the risk.
Keywords: Epidemiology; Incidence; Osteoporosis; Second Hip Fracture.