title: Chronic subdural hematoma management: clarifying the definitions of outcome measures to better understand treatment efficacy - a systematic review and meta-analysis.
abstract: A long history of inconsistencies in the definitions of the outcome measures for chronic subdural hematomas (CSDHs) has contributed to the controversy over the optimal surgical strategy for CSDH treatment. Clarifying these definitions, reassess the available data, and systematically review the prior literature may provide better insight into the differences in treatment efficacy for CSDH.
  
  
  
  The clinical course of CSDH was described with a series of strictly defined outcome measures. PubMed, Cochrane Library, and ScienceDirect databases were searched for comparative studies of two main surgical techniques for CSDH, including burr hole craniotomy (BHC) and twist drill craniotomy (TDC). Data were collected with uniform criteria and analyzed using a random-effects model to estimate the mortality, recurrence, operative failure, and cure rates of each treatment.
  
  
  
  Twelve comparative studies that examined 2,027 CSDH patients were included. The analysis results indicated that TDC and BHC treatments were similar in the mortality rates (RR, 1.25; 95% CI, 0.83-1.87; I2 = 0%; p = 0.28) and the recurrence rates (RR, 1.29; 95% CI, 0.87-1.92; I2 = 13%; p = 0.21) for CSDH patients. However, TDC had a significantly higher operative failure rate compared with BHC (RR, 0.35; 95% CI, 0.15-0.83; I2 = 0%; p = 0.02), whereas patients treated by a TDC approach tended to achieve higher cure rates compared with BHC (RR, 0.92; 95% CI, 0.86-0.99; I2 = 55%; p = 0.02).
  
  
  
  The clarification of the definitions related to CSDH outcome facilitates the interpretation of differences in treatment efficacy. The TDC approach manifested a significantly higher operative failure rate compared with the BHC approach; however, TDC showed a tendency in achieving a long-term neurologic cure.
authors.affiliation: Department of Neurology, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, Jiangsu, China. dr.chenfeng@163.com.
authors.forename: C-S
authors.initials: CS
authors.lastname: Xu
authors.forename: M
authors.initials: M
authors.lastname: Lu
authors.forename: L-Y
authors.initials: LY
authors.lastname: Liu
authors.forename: M-Y
authors.initials: MY
authors.lastname: Yao
authors.forename: G-L
authors.initials: GL
authors.lastname: Cheng
authors.forename: X-Y
authors.initials: XY
authors.lastname: Tian
authors.forename: F
authors.initials: F
authors.lastname: Xiao
authors.forename: Q
authors.initials: Q
authors.lastname: Wan
authors.forename: F
authors.initials: F
authors.lastname: Chen
mesh_terms: D003399:Craniotomy / Q000379:methods*; D020200:Hematoma, Subdural, Chronic / Q000401:mortality / Q000601:surgery*; D006801:Humans; D012008:Recurrence; D016896:Treatment Outcome