Incidence and patient-related risk factors for external ventricular drain-related cerebrospinal fluid infections

Despite procedural standardization, external ventricular drain-related infections (EVD-RI) remain frequent, with reported incidences of 5–30%. The underlying risk factors, however, remain insufficiently understood and have been debated for decades. To address this, patient-related and periprocedural risk factors for EVD-RI in adults undergoing EVD placement were analyzed. This single-center cohort included adults receiving EVD implantation between 2014 and 2022. Suspected EVD-RI was defined according to Infectious Diseases Society of America (IDSA). Confirmed EVD-RI required a positive CSF culture and/or broad-range eubacterial PCR. The primary outcome was suspected EVD-RI. Patient-related factors were assessed for their role as independent predictors or confounders using a multivariable Cox proportional hazards model with purposeful variable selection. A total of 387 patients with 421 EVDs were included. Suspected EVD-RI occurred in 104 (26.9%) patients and confirmed EVD-RI in 63 (16.3%) patients. EVD exchange (HR: 3.13, 95% CI: 2.02-4.85, p < 0.001), aneurysmal subarachnoid hemorrhage (aSAH) (HR: 2.56, 95% CI: 1.40-4.68, p = 0.002), and non-aneurysmal SAH (HR: 2.11, 95% CI: 0.90-4.96, p = 0.09) were associated with a significantly higher risk, whereas postoperative systemic antibiotics given for other suspected infections (HR: 0.33, 95% CI: 0.21-0.51, p < 0.001) and additional implantation of neuromonitoring (HR: 0.54, 95% CI: 0.30-0.97, p = 0.04) were associated with a significantly lower risk for EVD-RI. EVD-RI risk is driven primarily by periprocedural rather than patient-related factors. Avoiding EVD exchanges, preventing leaks/obstruction, minimizing drainage duration, and early definitive diversion may reduce infections. • Purposeful Cox modelling identified independent predictors without confounding • Confirmed EVD-RI occurred in 16.3% of patients. • Periprocedural factors, not comorbidity, primarily drove EVD-RI risk • EVD exchange and subarachnoid hemorrhage increased infection risk • Postoperative systemic antibiotics and additional neuromonitoring reduced EVD-RI