Factors associated with success of conservative therapy in chronic subdural hematoma: a single-center retrospective analysis

Introduction: Conservative therapy is a viable option for patients with chronic subdural hematoma (cSDH) who express no, or only mild symptoms. It is not clear which factors are associated with success of conservative therapy. This study aims to determine conservative therapy's success rate and to identify features possibly associated with success. Methods: A monocenter retrospective cohort study, including cSDH patients treated conservatively (wait-and-watch) from 2012 to 2022, was performed. The primary outcome was success of conservative therapy, defined as ‘no crossover to surgery’ during the follow-up period. Secondary outcomes were (1) factors associated with success, analyzed with univariate and multivariable logistic regression analyses, (2) 30-day mortality (3) time to crossover and (4) reasons for crossover. Results: We included 159 patients. Conservative therapy was successful in 96 (60%) patients. Hematoma volume (OR 0.79, 95% CI 0.69–0.92) and hypodense hematoma type (OR 3.57, 95% 1.38–9.23) were associated with success. Thirty-day mortality rate was 5% and the median duration between diagnosis and surgery was 19 days (IQR 8–39). Clinical deterioration was the most frequent reason for crossover (in 61/63 patients, 97%) and was accompanied by radiological hematoma progression in 42 patients (67%). Conclusion: In this selected group of patients, conservative therapy was successful in 60%. Smaller hematoma volume and hypodense hematoma type were associated with success. As time until crossover was approximately three weeks, deploying conservative therapy as primary treatment seems safe and could be rewarding as surgical complications can be avoided. Improvement in patient selection in future cohorts remains warranted.