Objectives: External Ventricular Drain (EVD) insertion is a common neurosurgical procedure. EVD-related infection (ERI) is a major complication that can lead to morbidity and mortality. In this study, we aimed to establish a national ERI rate in the United Kingdom (UK) and Ireland and determine key factors influencing the infection risk.
Methods: A prospective multi-centre cohort study of EVD insertions in 21 neurosurgical units was performed over 6 months. The primary outcome measure was 30-day ERI. A Cox Regression Model was used for multivariate analysis to calculate Hazard Ratios (HR).
Results: A total of 495 EVD catheters were inserted into 452 patients with EVDs remaining in-situ for 4700 days (median 8 days; interquartile range 4-13). Of the catheters inserted, 188 (38%) were antibiotic-impregnated, 161 (32.5%) were plain and 146 (29.5%) were silver-bearing. A total of 46 ERIs occurred giving an infection risk of 9.3%. Cox regression analysis demonstrated that factors independently associated with increased infection risk included duration of EVD placement for ≥8 days [HR=2.47 (1.12-5.45); p=0.03], regular sampling (daily sampling [HR=4.73 (1.28-17.42), p=0.02] and alternate day sampling [HR=5.28 (2.25-12.38); p<0.01]). There was no association between catheter type or tunnelling distance and ERI.
Conclusions: In the UK and Ireland, the ERI rate was 9.3% during the study period. The study demonstrated that EVDs left in situ for ≥8 days and those sampled more frequently were associated with a higher risk of infection. Importantly, the study showed no significant difference in ERI risk between different catheter types.