Optimal Drainage Duration Following Chronic Subdural Hematoma Evacuation: A Systematic Review and Meta-analysis

Introduction: Postoperative drainage following chronic subdural hematoma (CSDH) evacuation is known to reduce recurrence risk, but the optimal drainage duration remains unclear. This study aims to determine the most effective drainage time that minimizes recurrence rates and improves patient outcomes.

Methods: A systematic review of PubMed, Cochrane, and Embase databases was conducted, focusing on English-language studies comparing drainage durations after CSDH evacuation. Hematoma recurrence was the primary outcome, with mortality and complications as secondary outcomes. Proportions and Risk Ratios (RRs) with 95% confidence intervals (CIs) were calculated using RStudio V4.4.0 with a random-effects model, and heterogeneity was assessed with the I² statistic.

Results: A total of 2,011 patients from nine studies were included. Recurrence rates were significantly higher when drainage was limited to ≤12 hours, with 23.57 events per 100 observations (95% CI 18.31–28.83). For drainage durations of ≤24 hours and ≤48 hours, the recurrence rates were 13.31 per 100 observations (95% CI 8.75–17.87) and 11.75 per 100 observations (95% CI 7.53–15.98), respectively. The lowest recurrence rate was observed with drainage durations exceeding 48 hours, with a pooled event rate of 7.83 per 100 observations (95% CI 4.86–10.80). No significant differences in mortality (RR 1.35, 95% CI 0.46–3.98, p = 0.586), respiratory infections (RR 1.07, 95% CI 0.60–1.92, p = 0.811), or seizures (RR 0.97, 95% CI 0.37–2.60, p = 0.959) were found between drainage times of ≤24h and >24h.

Conclusion : Drainage lasting over 48 hours showed the lowest recurrence rates after CSDH evacuation, indicating a possible advantage of extended drainage. No significant differences in mortality, infections, or seizures were found between ≤24h and >24h drainage durations. Further studies are needed to confirm the optimal drainage time.