Deep infection after hip fracture surgery: predictors of early mortality

Abstract

Introduction: This study analysed the predictors of mortality in patients who are diagnosed with deep infection following hip fracture surgery.

Methods: Data were prospectively collected for 3 years from all patients undergoing hip fracture surgery and who had developed a subsequent deep infection. Infection was defined as positive microbiology culture from deep tissue or fluid samples. Demographic data, treatment, complications and subsequent surgeries were analysed. Potential predisposing factors including chronic medical co-morbidities, American Society of Anesthesiologists (ASA) grade, alcohol excess and smoking were assessed. The main outcome measures were 30-day and 1-year mortality.

Results: There were 2718 consecutive operations performed for a fracture of the proximal femur over a 3-year period. Forty-three (1.6%) patients had a deep postoperative infection diagnosed on fluid and/or tissue sampling. The mean age was 73 years (25-94) and 65% were female. Of the 43 patients who developed deep infection, the primary procedure in 25 (58%) patients was reduction and internal fixation, with 18 (42%) undergoing hemi-arthroplasty. The most common causative organism was Staphylococcus epidermidis (n=13, 30%), with methicillin-resistant Staphylococcus aureus (MRSA) accounting for 23% (n=10). The 30-day mortality was significantly higher than that of patients with no deep infection (19% vs. 6.5%; p=0.004). On univariate analysis, increasing age, dementia and diabetes were predictive of both 30-day and 1-year mortality (all p<0.05). S. aureus (sensitive or resistant) was approaching significance at 1 year (p=0.065). On multivariate analysis, dementia and diabetes were independent predictors of 30-day mortality, with dementia and S. aureus predictive at 1 year.

Conclusions: The 30-day mortality rate in patients diagnosed with deep infection following hip fracture surgery is higher than those without infection. Dementia, diabetes and S. aureus infection are independent predictors of mortality following deep infection.