Laboratory Parameters Associated with Reoperation in Chronic Subdural Hematoma: A Retrospective Cohort Study with Sex-Stratified Analyses

Chronic subdural hematoma (cSDH) frequently recurs after surgery, yet the prognostic relevance of routinely available laboratory parameters remains insufficiently characterized. This study evaluated demographic and laboratory correlates of reoperation after cSDH surgery, with emphasis on sex-specific differences.

We retrospectively analyzed 310 consecutive adults undergoing cSDH surgery at a tertiary center (2015-2024). Demographic and admission laboratory variables were assessed using univariable comparisons with Benjamini-Hochberg correction, followed by multivariable logistic and LASSO regression with prespecified candidate variables, including exploratory sex-stratified analyses.

Seventy-seven patients (25%) underwent reoperation, with a median interval of 15 days. Median age was 77 years, and 70% were male. In multivariable analysis, lower platelet count was associated with reoperation in the overall cohort (OR 0.99, p = 0.021). In the sex-stratified multivariable analysis, lower body weight (OR 0.96, p = 0.033), lower platelet count (OR 0.99, p = 0.005), and higher TSH (OR 1.60, p = 0.004) were independently associated with reoperation among male patients. The female-specific LASSO model did not identify any variables with reoperation. However, the limited number of reoperation events (n = 18) in this subgroup and poor cross-validated model discrimination (AUC 0.43) substantially constrain the interpretation of this result.

Routinely available baseline laboratory parameters, particularly lower platelet count, may provide relevant prognostic information for reoperation after cSDH surgery. Sex-stratified analyses identified additional but exploratory associations, suggesting that sex may modestly influence the contribution of individual laboratory parameters to reoperation risk.