Subdural Hematoma: Predictors of Outcome and a Score to Guide Surgical Decision-Making

There is little evidence to guide patient selection for subdural hemorrhage (SDH) evacuation. This study was designed to assess the benefit of surgical evacuation of SDH, identify predictors of functional outcome, and create a bedside score to guide the clinical management of SDH.

A cohort of 331 patients presenting to a single center from 2010 to 2014 with a principal diagnosis of subdural hemorrhage was identified. Clinical and radiographic information were extracted from the medical record. Outcomes of interest were (1) the occurrence of surgical evacuation of SDH, and (2) an unfavorable 90-day functional status represented by a modified Rankin score (mRS) ≥ 3. Propensity score matching and adjustment techniques were employed to assess the benefit of surgery accounting for confounding by indication. Multivariable logistic regression models predicting follow-up functional outcome were generated and bootstrapped separately among those with acute SDH and those with either subacute or chronic SDH. Clinical scores were created using model coefficients.

In this cohort [65% male, mean age 67 years], 47% underwent surgery. Age, focal neurologic deficit, SDH thickness > 10 mm, midline shift > 5mm, and SDH acuity predicted undergoing surgery. Propensity score matching analysis demonstrated that operated patients overall were less likely to have unfavorable 90-day mRS outcome (OR 0.35, 95% C.I. 0.15-0.82). Among patients with acute SDH, age, female sex, pre-admission mRS, focal neurologic deficit, and neuropsychiatric symptoms predicted 90-day functional outcome (c-statistic 0.89, optimism-corrected c-statistic 0.87) and were incorporated into an acute SDH score (range 1-10). Patients with SDH score > 4 were significantly more likely to have an unfavorable outcome if treated medically versus surgically; there was no difference in 90-day functional status by treatment strategy among patients with SDH score ≤ 4. No difference in outcome was seen by surgical status across the spectrum of chronic SDH scores.

Surgical evacuation of subdural hematomas overall is associated with favorable outcome. Patient selection for evacuation is enhanced by the application of the acute SDH score. Future studies are necessary to validate the SDH score in an external cohort.