Efficacy and safety of subdural drains after burr-hole evacuation of chronic subdural hematomas: systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: To determine whether the use of a subdural drain after burr-hole evacuation of a chronic subdural hematoma is safe and effective in preventing recurrence and subsequent operations, and as such improving functional outcomes.

METHODS: The literature search included the following databases: PubMed, the National Institutes of Health/National Library of Medicine, Clinical Trials Registry, CENTRAL (The Cochrane Library), EMBASE, and LILACS. The search was performed in June 2013, and did not have restrictions or filters with regard to language or year of publication. Methodologic quality was assessed through the Jadad's scale. Primary outcomes were recurrence and reoperation rates. Secondary outcomes were functional outcome, mortality, and postoperative complications. Results were presented as pooled Mantel-Haenszel relative risks (RR), with 95% confidence intervals (95% CI).

RESULTS: A total of 7 randomized controlled trials were analyzed. Three studies were classified as high methodologic quality and four as low quality. Pooled RR were symptomatic recurrence (RR 0.51; 95% CI 0.36-0.75), reoperation (RR 0.5; 95% CI 0.34-0.74), poor functional outcome (RR 0.61, 95% CI 0.39-0.98), mortality (RR 0.67, 95% CI 0.37-1.22), and postoperative complications (RR 1.28, 95% CI 0.78-2.11). There was no statistically significant heterogeneity within the outcomes.

CONCLUSIONS: The meta-analysis demonstrates that the insertion of a subdural drain was associated with a statistically significant reduction in the risk of symptomatic recurrence and the requirement for further surgical intervention of chronic subdural hematoma after surgical evacuation. Furthermore, it was associated with statistically significant improvements in both short-term and long-term functional outcome.