Role of brain natriuretic peptide in the prediction of long-term surgical outcome of chronic subdural hematoma

Objective: To investigate the role of brain natriuretic peptide (BNP) in predicting long-term functional outcome and develop a new predictive score of poor functional outcome after surgery for chronic subdural hematoma (cSDH).

Methods: Patients with cSDH that were surgically treated in our department between November 2016 and December 2019 were included in the study. Pre- and postoperative plasma BNP and clinical condition were prospectively recorded. At follow-up (5-6 months), a simplified modified Rankin Scale (mRS) questionnaire was conducted through a standardized telephone interview. A poor outcome was defined by a mRS > 3. Based on predictors of the long-term functional outcome, a score was calculated. Its accuracy was tested using the area under the curve (AUC) of the receiver operating characteristic analysis.

Results: In total, 119 patients were analyzed (median age: 76 years, range: 44-94 years). Preoperative plasma BNP (BNP-1) was elevated in 77 patients (64.7%). For the follow-up phone interview, 101 patients (84.8%) were available. In the multivariate analysis, poor outcome at follow-up could be predicted using BNP-1 (p = 0.034), age (p = 0.036), motor deficit (p = 0.013) and Glasgow coma scale score on admission (p = 0.008). The "Functional Long-term Outcome Predictive score" (FLOP-score) was therefore computed, and revealed an excellent discriminative capacity compared to other scores, with an AUC of 0.86 (0.77-0.95).

Conclusions: Preoperative plasma BNP is an independent predictor of functional outcome at follow-up. Using the FLOP-score, the risk of experiencing a poor outcome could accurately be predicted.