title: A multistudy analysis investigating systematic differences in cardiovascular trial results between Europe and Asia.
abstract: OBJECTIVE
  To assess whether there are differences in the results of cardiovascular trials between Europe and Asia using data from an extensive collection of randomised controlled trials.
  
  
  METHODS
  All meta-analyses containing randomised controlled trials (RCT's) for the treatment or prevention of cardiovascular diseases were searched for in The Cochrane Library (2000-2008) and MEDLINE (2005-2008). Analysis was then conducted within and over each meta-analysis which satisfied given criteria. Separate estimates of treatment effect were calculated for Europe and Asia in each meta-analysis and then compared. Estimates of a common inter-continental difference over all meta-analyses were also calculated and meta-regression was performed. This was performed for both fatal and non-fatal end points.
  
  
  RESULTS
  The literature search identified 59 meta-analyses that satisfied the inclusion criteria. After exclusion, the number of meta-analyses reporting greater effect sizes in Asia than in Europe was significantly more than would be expected by chance (fatal 12/14, p=0.013; non-fatal 23/32, p=0.020).
  
  
  CONCLUSIONS
  This study provides some evidence that for cardiovascular interventions treatment effect estimation differs between Europe and Asia, with respect to both fatal and non-fatal end points.
authors.affiliation: Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry, UK School of Health and Population Sciences, University of Birmingham, Birmingham, UK.
authors.forename: Louise C
authors.initials: LC
authors.lastname: Hartley
authors.affiliation: School of Health and Population Sciences, University of Birmingham, Birmingham, UK.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Girling
authors.affiliation: Faculty of Engineering, Universidad Autónoma de Querétaro, Cerro de las Campanas, Santiago de Querétaro, Qro, Mexico.
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Bowater
authors.affiliation: School of Health and Population Sciences, University of Birmingham, Birmingham, UK.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Lilford
mesh_terms: D001208:Asia / Q000453:epidemiology; D002318:Cardiovascular Diseases / Q000401:mortality / Q000628:therapy*; D003431:Cross-Cultural Comparison; D016206:Databases, Bibliographic; D023381:Endpoint Determination; D005060:Europe / Q000453:epidemiology; D006801:Humans; D010043:Outcome and Process Assessment, Health Care / Q000706:statistics & numerical data*; D017594:Publication Bias; D016032:Randomized Controlled Trials as Topic / Q000592:standards / Q000706:statistics & numerical data*; D012107:Research Design
keywords: Cardiovascular disease; META ANALYSIS; SYSTEMATIC REVIEWS