Predictors of Thirty-day Mortality and Length of Stay in Operative Subdural Hematomas

The rate of postoperative morbidity and mortality after subdural hematoma (SDH) evacuation is high. The aim of this study was to compare mortality statistics from a high-volume database to historical figures and determine the most significant preoperative predictors of mortality and length of stay (LOS). The National Surgical Quality Improvement Program registry was searched (2005-2016) for patients with operatively treated SDHs, of which 2709 were identified for univariate analysis. After exclusion for missing data, 2010 individuals were analyzed with multivariable logistic regression. Primary outcome was 30-day mortality. The average patient age was 68.8 +/- 14.9 years, and 64.1% were males. Upon multivariate analysis, nine variables were found to be associated with increased mortality: platelet count < 135,000 (OR 2.04, 95% CI 1.39-2.99), INR >1.2 (OR 1.87, 95% CI 1.34-2.6), bleeding disorder (OR 1.80, 95% CI 1.32-2.46), need for dialysis within two weeks preoperatively (OR 5.69, 95% CI 3.15-10.27), ventilator dependence in the 48 hours preceding surgery (OR 3.99, 95% CI 2.82-5.63), disseminated cancer (OR 2.95, 95% CI 1.34-6.47), WBC count >10,000 (OR 1.55, 95% CI 1.15-2.08), totally dependent functional status (OR 1.84, 95% CI 1.2-2.8), and each increasing year of age (OR 1.04, 95% CI 1.031-1.05). It is not surprising that chronic conditions and functional status were associated with increased mortality. However, specific laboratory abnormalities were also associated with increased mortality at levels generally considered within normal limits. More studies are needed to determine if correcting lab abnormalities preoperatively can improve outcomes in patients with intrinsic coagulopathy.