Risk Factors for Acute Surgical Site Infection after Spinal Instrumentation Procedures: A Case-Control Study

Background Surgical site infection (SSI) prevalence in spinal instrumentation varies, depending on patient and surgery factors. This study aims to identify patient- and procedure-related factors associated with SSI after spinal instrumentation in 3 patient-specific groups: those undergoing surgery for degenerative, trauma-related, and pediatric deformity conditions.

Methods A case-control (1:2 ratio) analysis of SSI after spinal instrumentation, from 2009 to 2017, in a University Hospital and Spinal Trauma Centre was performed.

Results From a total of 2582 surgeries, 33 cases (1.3%) were identified with SSI according to study inclusion criteria: 14 (out of 1326) in the degenerative group, 11 (out of 207) in the trauma group, and 8 (out of 850) in the pediatric deformity group. Cases were matched with controls (n = 66) of the same group. Univariate analysis identified procedure and anesthesia duration in the degenerative group (P = .032 and .038, respectively), age (P = .014) and need for intraoperative and postoperative blood transfusions (both P = .039) in the trauma group and American Society of Anesthesiologists score (P = .022) and neuromuscular scoliosis (P = .002) in the pediatric deformity group as associated with SSI. After multivariate analysis, procedure duration was independently associated with SSI in degenerative surgery (odds ratio [OR], 2.23; 95% confidence interval [CI], 1.03–4.82) and procedure duration (OR, 3.79; 95% CI, 1.27–11.32) and number of levels instrumented (OR, 11.77; 95% CI, 1.55–89.40) in the trauma group.

Conclusions This study identified procedure duration as a risk factor for SSI after spinal instrumentation in degenerative and trauma spine surgery and the number of levels instrumented in trauma spine surgery. Awareness of these factors will help develop strategies to improve patient and health system overall outcomes.