title: Application of beta regression to analyze ischemic stroke volume in NINDS rt-PA clinical trials.
abstract: OBJECTIVE
  Ischemic stroke lesion volumes have proven difficult to analyze due to the extremely skewed shape of their underlying distribution. We introduce an extension of generalized linear models, beta regression, as a possible method of modeling extremely skewed distributions as evidenced in ischemic stroke lesion volumes.
  
  
  METHODS
  The NINDS rt-PA clinical trials measured ischemic stroke lesion volume as a secondary trial outcome. Three-month lesion volumes from these trials were analyzed using beta regression. A multi-variable regression model associating explanatory variables with ischemic stroke lesion volumes was constructed using accepted model building strategies and compared with the previously published volumetric analysis.
  
  
  RESULTS
  Beta regression produced a similar model when compared to the previous analysis published by the study group. All previously identified variables of importance were detected in the model building process. The age by treatment interaction described in previous studies was also found in this analysis, confirming the strong effect age has on stroke outcomes. Further, a treatment effect was elicited in terms of odds ratios, yielding a previously unknown quantification of the effect of rt-PA on lesion volumes.
  
  
  CONCLUSIONS
  Beta regression proved adept in modeling ischemic stroke lesions and offered the interpretation of covariates in terms of odds ratios. Beta regression is seen as a legitimate alternative to analyze ischemic stroke volumes.
authors: Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72202, USA. cswearingen@uams.edu
authors: Christopher J
authors: CJ
authors: Swearingen
authors: Barbara C
authors: BC
authors: Tilley
authors: Robert J
authors: RJ
authors: Adams
authors: Zoran
authors: Z
authors: Rumboldt
authors: Joyce S
authors: JS
authors: Nicholas
authors: Dipankar
authors: D
authors: Bandyopadhyay
authors: Robert F
authors: RF
authors: Woolson
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000188:drug therapy* / Q000453:epidemiology / Q000503:physiopathology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055825:National Institute of Neurological Disorders and Stroke (U.S.) / Q000706:statistics & numerical data; D012044:Regression Analysis; D020521:Stroke / Q000188:drug therapy* / Q000453:epidemiology / Q000503:physiopathology; D013318:Stroke Volume / Q000187:drug effects* / Q000502:physiology; D010959:Tissue Plasminogen Activator / Q000494:pharmacology / Q000627:therapeutic use*; D014481:United States / Q000453:epidemiology
chemical_list: D010959:Tissue Plasminogen Activator