RISK-FACTORS FOR NEUROSURGICAL SITE INFECTIONS AFTER CRANIOTOMY - A PROSPECTIVE MULTICENTER STUDY OF 2944 PATIENTS

OBJECTIVE: To determine the incidence and risk factors of surgical sit e infections (SSIs) after craniotomy and to test the risk index score proposed by the National Nosocomial infections Surveillance (NNIS) sys tem, which, to our knowledge, has not been validated in neurosurgery t o date. METHODS: During a 15-month period, every adult patient undergo ing craniotomy in 10 neurosurgical units was prospectively evaluated f or development and risk factors of SSI. The follow-up period was at le ast 30 days. SSIs were defined according to the Center for Disease Con trol definitions. Incidence was calculated per patient. Multivariate a nalyses were conducted at first to include all significant risk factor s of univariate analysis and then only those known preoperatively. Fin ally, the NNIS risk index was tested in this population, RESULTS: Of a total of 2944 patients, 117 patients (4%) with SSIs were observed, in cluding 30 with wound infections, 14 with bone flap osteitis, 56 with meningitis, and 17 with brain abscesses. independent risk factors for SSIs were postoperative cerebrospinal fluid leakage (odds Patio, 145; 95% confidence interval, 72-293) and subsequent operation (odds ratio, 7; 95% confidence interval, 4-12). Independent predictive risk factor s were emergency surgery, clean-contaminated and dirty surgery, an ope rative time longer than 4 hours, and recent neurosurgery. Absence of a ntibiotic prophylaxis was not a risk factor. The NNIS risk index was e ffective in identifying at-risk patients. CONCLUSION: Independent risk factors for SSIs after craniotomy involve postoperative events. Howev er, the NNIS risk index is effective in identifying at-risk patients.