Incidence and risk factors of neurosurgical site infections: results of a prospective multicenter cohort study on 6359 surgeries

BACKGROUND: Neurosurgical surgical site infections (SSI) are life-threatening complications, requiring medical treatment and additional surgeries and remain a substantial cause of morbidity. In order to identify the incidence and the main risk factors for SSI, we developed the Prophylaxis with Antibiotic Protocol for Neurosurgical Site Infections Study (PASSIS), a prospective observational multicenter cohort study for examining a large number of neurosurgical procedures. METHODS: The study PASSIS involved four Italian departments of neurosurgery applying the same antibiotic prophylaxis (ABP) protocol on 6359 consecutive neurosurgical procedures. In high-risk conditions (intra-operative contamination and/or postoperative cerebro-spinal fluid [CSF], and/or subcutaneous drainage and/or postoperative hyperpyrexia) and in presence of wound complication (CSF leak and/or CSF collection and/or wound diastasis), a prolongation protocol was prescribed. RESULTS: The crude rate of SSI in the whole series was and 1.7% for patient and 1.5% for procedure. Patient related SSI risk factors: Younger patients (<= 14 years) had a significantly higher SSI risk compared with older patients (RR: 2.17; 95% CI: 1.13-4.14). Patients underwent two surgeries were at increased SSI risk (RR: 3.80; 95% CI: 2.33-6.18), and the risk increased with the number of surgeries. Surgeries lasting longer than 3 hours (RR: 2.27; 95% CI: 1.15-4.50), undergoing two or more surgeries and the presence of prosthetic implants (RR: 2.40; 95% CI: 1.53-3.77) were procedure related SSI risk factors positively associated with SSI. In high-risk conditions and in wound complication as defined previously, ABP prolongation showed limited efficacy (RR:1.97; 95% CI: 1.21-3.22 and 9.31; 95% CI: 5.90-14.68 respectively). CONCLUSIONS: The subjects submitted to complicated, repeated, long lasting craniotomies, especially if experiencing postoperative deterioration, display the higher risk of SSIs, as a final life-threatening complication. In order to reduce the SSI rate, further studies should address to design tailored prophylaxis protocols for each high risk situation as hereby defined; the wound complications deserve an increased microbiological surveillance, focusing the attention on the timing and source of infections.

Automated summary

The study revealed that the overall rate of SSI was 1.7% for patients and 1.5% for procedures. Factors such as surgeries lasting longer than 3 hours, undergoing two or more surgeries, and having prosthetic implants were positively associated with SSI risk. Prolonging antibiotic prophylaxis showed limited efficacy in high-risk conditions and wound complications.