Risk factors correlated with post-operative mortality for hip fracture surgery in the elderly: a population-based approach.

Objectives: To estimate the effect of waiting time for surgery and volume of surgical activity on mortality in patients with hip fracture and to compare risk-adjusted outcomes between hospitals providing surgery for such patients.
Design: Retrospective cohort study.
Setting: Friuli Venezia Giulia, Italy.
Participants: A total of 6,629 elderly people who underwent surgery for hip fracture between 1st January 1996 and 31th December 2000.
Main Outcome Measures: In-hospital, 6-month and 1-year mortality rate.
Results: In-hospital mortality rate was 5.4%. At six months, the mortality rate was 20.0%, and at 1 year 25.3%. Age, male sex, and comorbidity were significant predictors of mortality. Logistic regression analysis indicated that, after controlling for main patients risk factors and taking into account the hospital level variability, there was no significant association between increase in mortality rate and more than 1 day of waiting time for surgery (OR 0.90; 95% CI 0.58-1.40 for in-hospital mortality). One hospital had a significantly higher mortality rate than the others; high hospital volume for hip fracture surgery was associated with worse outcomes (OR 1.57; 95% CI 1.38-1.78 for in-hospital mortality). Mortality after hip fracture decreased significantly from 1996 to 2000 (OR 0.85; 95% CI 0.80-0.90).
Conclusions: Longer waiting time for surgery was not associated with mortality after adjusting for patient risk factors, and taking into account hospital level variability. Hospital level variability was statistically significant, and was partially explained by the total volume of hospital surgical activity. The decrease in mortality between 1996 and 2000 was confirmed by multivariate models.