Table 2. Baseline Characteristics of Patients With Nontraumatic Subdural Hematoma in a 5% Nationally Representative Sample of Medicare Beneficiaries, Stratified by Whether Repeated Operation Was Required Within 90 Days.

Characteristic	Repeated Operation (n = 103)	No Repeated Operation (n = 1431)
Age, mean (SD), y	78.0 (6.8)	77.7 (7.0)
Female, No. (%)	24 (23.3)	474 (33.1)
White race/ethnicity, No. (%)	88 (85.4)	1156 (80.8)
Charlson comorbidity index score, mean (SD)	2.6 (1.7)	2.8 (1.6)