Optimal duration of postoperative drainage following burr hole surgery for chronic subdural hematoma: A systematic review and network meta-analysis

Chronic subdural hematoma (CSDH) is a prevalent neurosurgical condition with a high recurrence rate after burr-hole surgery. The optimal duration of postoperative drainage remains controversial, with varying clinical practices worldwide. This systematic review and network meta-analysis aimed to determine the optimal postoperative drainage duration to minimize recurrence while maintaining favorable clinical outcomes. A comprehensive search was conducted across five databases up to January 2025, including randomized controlled trials (RCTs) and cohort studies evaluating the postoperative drainage duration in CSDH patients undergoing burr-hole surgery. The primary outcome was recurrence rate, while the secondary outcomes included mortality and functional outcomes. A random-effects network meta-analysis was performed, and the risk of bias was assessed using standardized tools. Seven studies with 1,842 patients were included, comprising three RCTs and four cohort studies. Drainage durations of 3 and 6 days significantly reduced recurrence rates compared with shorter durations (0–8 h and 17–24 h). Notably, the 6-day drainage had the highest probability (86.2%) of minimizing recurrence, followed by the 3-day drainage (13.8%). A shorter drainage duration (< 24 h) was associated with higher recurrence risks. However, no significant differences in mortality rates were observed across the drainage durations. This study highlights that longer postoperative drainage durations (3–6 days) may reduce recurrence rates after burr-hole surgery for chronic subdural hematomas. However, its effect on mortality remains unclear. These findings support the importance of optimizing the drainage duration and call for further high-quality studies to guide clinical practice.