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

Abstract

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.