Early and late mortality in elderly patients after hip fracture: a cohort study using administrative health databases in the Lazio region, Italy

Background: Hip fractures represent one of the most important causes of morbidity and mortality in elderly people. We evaluated the risk and the potential determinants of early, mid and long term mortality, in a population-based cohort of subjects aged >= 65 years old. Methods: Using hospital discharge database we identified all hospitalized hip fracture cases of 2006, among residents in Lazio Region aged >= 65 years old. The mortality follow-up was performed through a deterministic record-linkage between the cohort and the death registry for the years 2006 and 2007. Kaplan-Meier method was used to calculate cumulative survival probability after admission. Shared frailties Cox regression model was used to estimate adjusted hazard ratios (HRs) for early (within 1 month), mid (1-6 months) and long term (6-24 months) mortality. As possible cofactors we considered age, gender, marital status, education degree, comorbidities, surgical intervention, and hospital volume of surgical treatment for hip fracture. Results: We identified 6,896 patients; 78% were females, median age was 83 and 9% had two or more comorbidities. Five percent died during hospital stay; the cumulative probability of dying at 30, 180 days, and at 2 years was 7%, 18% and 30%. In the first month following admission, we found a significantly increased HR with older age, male sex, not married status, history of hearth disease, chronic pulmonary and renal disease; for those who had surgery there was a significantly increased HR within two days after surgical intervention and a significantly decreased HR thereafter compared to those who received a conservative management. Between 1 and 6 months significantly increased HRs were for older age, male sex and higher hospital volume of surgical treatment. After six months, significantly increased HRs were for older age, male sex, presence of dementia and other low prevalence diseases. Conclusion: In Lazio region the risk of dying after hip fracture is similar to that found in high-income countries. Both clinical and organizational factors of acute care are associated with the risk of early mortality. As time passes, some of these factors tend to become less important while older age, male gender, the presence of cognitive problems and the presence of other comorbidities remain significant.