Preoperative CT markers and poor discharge functional status after burr-hole drainage for chronic subdural hematoma:...

Chronic subdural hematoma (CSDH) is among the most common neurosurgical conditions in older adults, yet preoperative predictors of short-term functional status after surgical evacuation remain incompletely defined. In this exploratory study we evaluated whether preoperative computed tomography (CT) markers-specifically hematoma thickness and midline shift-are associated with poor discharge functional status after burr-hole drainage for CSDH, after adjustment for established clinical factors.

We retrospectively analyzed 260 consecutive adult patients who underwent burr-hole drainage for CSDH at a single institution between January 2018 and December 2023. Because of the retrospective design and absence of prospective registration, the findings were interpreted as exploratory. The primary outcome was poor discharge functional status, defined as a modified Rankin Scale (mRS) score ≥3 at hospital discharge. Multivariable logistic regression identified factors independently associated with the primary outcome. Restricted cubic spline (RCS) analysis examined dose-response relationships. Model performance was characterized by discrimination (area under the receiver operating characteristic curve [AUC] with bootstrap optimism correction), calibration (Hosmer-Lemeshow test and calibration plot), Brier score, and decision curve analysis (DCA) across nested models.

Among 260 patients (mean age 72.9 ± 9.1 years; 70.4% male), 66 (25.4%) had poor discharge functional status. In the full multivariable model, midline shift (adjusted odds ratio [aOR] 1.11, 95% CI 1.01-1.22; p = 0.036), pre-hospital mRS (aOR 1.39, 95% CI 1.05-1.85; p = 0.022) and age (aOR 1.08, 95% CI 1.04-1.12; p < 0.001) were independently associated with the primary outcome. Hematoma thickness was numerically positively associated with poor outcome but did not meet the predefined two-sided p < 0.05 threshold (aOR 1.05, 95% CI 1.00-1.11; p = 0.067). RCS analysis was consistent with approximately linear dose-response relationships for hematoma thickness (Pnon-linearity = 0.654) and midline shift (Pnon-linearity = 0.094). The full model achieved an apparent AUC of 0.733, with bootstrap-corrected AUC of 0.721 (optimism = 0.012). Calibration was acceptable (Hosmer-Lemeshow p = 0.42; Brier score 0.168), and DCA showed positive net benefit across threshold probabilities of approximately 10-45%.

In this single-center retrospective cohort, midline shift, pre-hospital functional status and age were independently associated with poor discharge functional status after burr-hole drainage for CSDH. These exploratory, hypothesis-generating findings may assist preoperative risk stratification, patient and family counseling, postoperative monitoring intensity, and early rehabilitation planning, but should not be used as a stand-alone basis for treatment decisions. External validation in independent multicenter cohorts using longitudinal outcome scales (e.g., 3- or 6-month mRS or Glasgow Outcome Scale Extended) is required before clinical implementation.