Prior Hospitalization as an Independent Risk Factor for Surgical Site Infection in Spinal Surgery: A Retrospective Multicenter Study of 3275 Cases

Study Design: A retrospective multi-center study. Objective: To examine the relationship between prior hospitalization and surgical site infection (SSI) following spine surgery. Summary of Background Data: SSI is a major complication after spine surgery, resulting in a prolonged hospital stay, increased medical costs, and worsened patient outcomes. Despite a possible link between prior hospitalization and an increased risk of SSI, the impact of prior hospitalization on the risk of SSI following spine surgery has not been investigated. Materials and Methods: We retrospectively analyzed the data of patients who underwent spine surgery at three institutions in Japan between April 2019 and March 2024. SSI was defined in accordance with the guidelines of the Centers for Disease Control and Prevention and the National Healthcare Safety Network. Prior hospitalization was defined as an inpatient admission requiring a stay of at least two consecutive days. Multivariate logistic regression was performed to identify independent predictors of SSI. Results: A total of 3275 patients were included in the study (women, 41.3%; mean age: 65.8 yr old). Of these, 638 (19.5%, mean age: 69.7 yr) had a history of hospitalization. Overall, deep SSI occurred in 40 patients (1.2%). Prior hospitalization was associated with a higher incidence of SSI after spinal surgery (4.0% vs . 0.6%, P <0.001). Prior hospitalization was an independent risk factor for deep SSI (odds ratio, 6.98; 95% confidence interval, 3.54–13.70; P <0.001). Among SSI patients with prior hospitalization, those with drug-resistant bacteria (DRB) had a shorter interval between their last hospitalization and surgery than those with DRB-negative SSI (17.4 vs . 92.1 mo) ( P =0.013). Conclusions: A history of hospitalization was associated with an increased risk of deep SSI after spine surgery. Information on prior hospitalization may help to identify patients at an increased risk of SSI and should be included in the preoperative assessment.