Incidence and risk factors associated with surgical site infection after surgically treated hip fractures in older adults: a retrospective cohort study

Background Surgical site infection (SSI) is one of the most common complications in the traumatic orthopedics field, but remains not adequately studied after hip fractures. Aims This study aims to investigate the incidence and risk factors associated with SSI after surgically treated hip fractures in older adults. Methods A retrospective cohort study including 2932 older adult patients (1416 with femoral neck fracture and 1516 with intertrochanteric fracture) surgically treated from Jan 2015 to Dec 2019 due to hip fractures was performed. Their data on demographics, injury-related data, surgery-related data, and preoperative laboratory test results were collected from hospitalization medical records. Univariate analyses were used to compare between the patients with and without SSI, and multivariate logistic regression analyses were used to identify the risk factors. Results A total of 89 patients developed SSI, with an accumulated incidence rate of 3.04% (95%CI 2.41-3.66). Staphylococcus aureus was the most common source of infection. In univariate analysis, 11 items were found to be significant in femoral neck fractures and 5 items were found to be significant in intertrochanteric fracture. In the multivariable logistic regression model, cerebrovascular disease (OR 2.17, 95%CI 1.14-4.15) and hematocrit (HCT) (< Lower limit) (OR 3.46, 95%CI 1.13-10.56) were independent risk factors for SSI in femoral neck fracture. Heart disease (OR 2.13, 95%CI 1.18-3.85) was a risk factor for SSI, while LDH (> 250 U/L) (OR 0.44, 95%CI 0.20-0.95) was a protective factor for SSI in intertrochanteric fracture. Discussion We observed 89 cases (3.04%) of SSI in 2932 older adult patients with hip fractures in this study. Cerebrovascular disease and lower HCT were two independent risk factors for SSI in femoral neck fracture, whereas heart disease was a risk factor and LDH was a protective factor for SSI in intertrochanteric fracture. Conclusions Targeted preoperative management, such as predicting the probability of SSI and taking appropriate measures accordingly is essential and highly regarded. Future multicentric studies with more patients evaluated are expected to better address the risk factors for SSI in older hip fracture patients.