Risk of acute renal failure and mortality after surgery for a fracture of the hip: a population-based cohort study

Abstract

Aims: We examined risk of developing acute renal failure and the associated mortality among patients aged > 65 years undergoing surgery for a fracture of the hip.

Patients and methods: We used medical databases to identify patients who underwent surgical treatment for a fracture of the hip in Northern Denmark between 2005 and 2011. Acute renal failure was classified as stage 1, 2 and 3 according to the Kidney Disease Improving Global Outcome criteria. We computed the risk of developing acute renal failure within five days after surgery with death as a competing risk, and the short-term (six to 30 days post-operatively) and long-term mortality (31 days to 365 days post-operatively). We calculated adjusted hazard ratios (HRs) for death with 95% confidence intervals (CIs).

Results: Among 13 529 patients who sustained a fracture of the hip, 1717 (12.7%) developed acute renal failure post-operatively, including 1218 (9.0%) with stage 1, 364 (2.7%) with stage 2, and 135 (1.0%) with stage 3 renal failure. The short-term mortality was 15.9% and 5.6% for patients with and without acute renal failure, respectively (HR 2.8, 95% CI 2.4 to 3.2). The long-term mortality was 25.0% and 18.3% for those with and without acute renal failure, respectively (HR 1.3, 95% CI 1.2 to 1.5). The mortality was higher in patients with an increased severity of renal failure.

Conclusion: Acute renal failure is a common complication of surgery in elderly patients who sustain a fracture of the hip, and is associated with increased mortality up to one year after surgery despite adjustment for coexisting comorbidity and medication before surgery. Cite this article: Bone Joint J 2016;98-B:1112-18.

Keywords: Acute renal failure; Hip fracture; Mortality.