Predicting Functional Impairment in patients with chronic subdural hematoma treated with burr hole Trepanation-The FIT-score

It remains difficult to estimate prolonged functional impairment in patients with chronic subdural hematoma (cSDH) treated with burr hole trepanation. We aim to establish a score that reliably predicts postoperative functional impairment.Retrospectively analysis of a prospective institutional database. cSDH patients operated in 2013-2016 were identified. Clinical outcome was dichotomized into presence (modified-Rankin-Scale (mRS) ≥ 2) or absence of functional impairment (mRS 0-1) at discharge and last follow-up. A score was developed, based on the effect sizes of a set of outcome predictors. Its accuracy was tested using Area Under the Receiver-Operating Characteristic (AUROC) curve analysis. The 2017 cohort served for internal validation.A cohort of 253 patients (mean age 75 years, 75% male) was analyzed, of which 77 patients (30%) remained functionally impaired. In multivariate analysis, severe motor deficits at admission (OR 5.84, 95% CI 2.71-12.59, p 0.001), age (≥85 years: 5.53, 2.14-14.32, p 0.0001) and disorientation at admission (2.65, 11.39-5.05, p = 0.003) were associated with persistent functional impairment. Based on those variables, we created the "Functional Impairment after burr hole Trepanation" (FIT-score), which showed an AUROC of 0.77 (95% CI 0.70-0.83) for impairment at discharge and 0.76 (0.70-0.82) for impairment at follow-up. Internal validation confirmed the model with an AUROC of 0.79 (0.68-0.91) at discharge and 0.77 (0.64-91) at follow-up.The FIT-score is likely to assist the physician when counseling patients and relatives pertaining to the need for postoperative rehabilitation and mid- to long-term supportive home care.