Chronic subdural haematoma (CSDH) is common in the elderly, with approximately 40% of patients with CSDH taking anti-thrombotic medications. Surgery necessitates temporary cessation. The optimal time of postoperative antithrombotic resumption is not known, with the risk of recurrence balanced against the risk of thrombosis. A systematic review was carried out (registration number:CRD42023427275). Medline and EMBASE databases were searched. The primary outcome of this study was recurrence. Late and early resumption was defined by study authors - a final definition was not possible given the heterogeneity amongst papers. 7 studies were included in the final analysis (3,195 patients total). Generally, studies reported higher risk of thromboembolic events in patients in late resumption groups (n = 4). On meta-analysis, there was no increased risk of recurrence in the early vs late groups (OR 0.61, 95% CI [0.016; 2.40], I² = 0%, p = 0.26). Most studies reported that early resumption was not associated with increased adverse events. Definitions of early and late varied by study (earliest range <3 days to <30 days). We found no significant difference in rates of recurrence, or thromboembolic events in those receiving early or late resumption of antithrombotic medication. Prospective studies with consensus definitions are required to inform clinical decision making and guidelines.

Chronic subdural haematoma (CSDH) is common in the elderly, with approximately 40% of patients with CSDH taking anti-thrombotic medications. Surgery necessitates temporary cessation. The optimal time of postoperative antithrombotic resumption is not known, with the risk of recurrence balanced against the risk of thrombosis. A systematic review was carried out (registration number:CRD42023427275). Medline and EMBASE databases were searched. The primary outcome of this study was recurrence. Late and early resumption was defined by study authors - a final definition was not possible given the heterogeneity amongst papers. 7 studies were included in the final analysis (3,195 patients total). Generally, studies reported higher risk of thromboembolic events in patients in late resumption groups (n = 4). On meta-analysis, there was no increased risk of recurrence in the early vs late groups (OR 0.61, 95% CI [0.016; 2.40], I² = 0%, p = 0.26). Most studies reported that early resumption was not associated with increased adverse events. Definitions of early and late varied by study (earliest range <3 days to <30 days). We found no significant difference in rates of recurrence, or thromboembolic events in those receiving early or late resumption of antithrombotic medication. Prospective studies with consensus definitions are required to inform clinical decision making and guidelines.