Optimal drain position after evacuation of chronic subdural hematomas: a systematic review and network meta-analysis

Background Chronic subdural hematoma (CSDH) is one of the most prevalent diseases encountered in neurosurgery. At present, burr-hole hematoma drainage has been established as the standard surgical intervention for CSDH, effectively reducing the risk of postoperative recurrence. The current study employed systematic review and network meta-analysis (NMA) to assess the impact of drain placement in three different anatomical locations—subdural drain (SDD), subperiosteal drain (SPD), and subgaleal drain (SGD)—on treatment outcomes. Methods A search was conducted across PubMed, Embase, Cochrane Library, and Web of Science up to February 14, 2026. The Newcastle–Ottawa Scale was used to assess the risk of bias. R (v4.4.0) and Stata18 were used for the NMA. Results This NMA included 14 articles comprising 4,161 patients. The drainage locations evaluated were SDD, SPD, and SGD. Pooled results were analyzed based on two classification systems: Classification I (anatomical location) and Classification II (anatomical location + technique). (1) Recurrence rate: Classification I: According to the league table, SGD was associated with a significantly lower recurrence rate versus No_drain [risk ratio (RR) = 0.43, 95% credible interval (CrI): 0.20–0.96]. Based on the surface under the cumulative ranking curve (SUCRA), SGD (78.25%) ranked as the best intervention. Classification II: According to the league table, subgaleal active drainage (SGD_a) was significantly associated with recurrence versus No_drain (RR = 0.26, 95% CrI: 0.10–0.75), and also ranked highest in SUCRA (79.83%). (2) Mortality: Classification I: SGD was associated with reduced mortality (SUCRA = 72.64%). Classification II: subdural irrigation drainage (SDD_irr) showed the best efficacy in reducing mortality (SUCRA = 63.85%). Conclusion SGD_a and SDD_irr exhibit significant potential in reducing recurrence rates and mortality, respectively, in the management of CSDH. However, due to the physiological conditions and disease features of old and high-risk populations, careful assessment is necessary when selecting treatment approaches in clinical practice. Further studies should be conducted to clarify the actual efficacy of these two treatment modalities. Systematic review registration This study is a systematic review and network meta-analysis and has been registered in the PROSPERO database. Registration ID: CRD42024587692. Official URL: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=587692 .