title: Comparing and combining studies of bronchial responsiveness.
abstract: BACKGROUND
  There is no standardised protocol for the measurement of bronchial responsiveness. Results from different studies are difficult to compare and combine.
  
  
  METHODS
  Analyses are divided between those of a continuous outcome, which can be directly standardised as effect size, and those based on a binary outcome. A published method is used to convert an odds ratio to equivalent effect size.
  
  
  RESULTS
  The use of effect size allows comparison between studies using a continuous outcome but different protocols, provided the relevant standard deviation is reported. Effect size from a continuous outcome and that derived from an odds ratio from an equivalent analysis gave similar results.
  
  
  CONCLUSIONS
  Systematic reviews which include both continuous effect estimates and odds ratios can include both in one meta-analysis, provided relevant standard deviations are published for the former. Authors are encouraged to report these in all fields in which measurement protocols vary.
authors.affiliation: Department of Public Health Sciences, King's College, Capital House, 42 Weston Street, London SE1 3QD, UK. sue.chinn@kcl.ac.uk
authors.forename: Susan
authors.initials: S
authors.lastname: Chinn
mesh_terms: D001249:Asthma / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000503:physiopathology*; D002985:Clinical Protocols; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D016017:Odds Ratio; D012044:Regression Analysis; D012964:Sodium / Q000652:urine
chemical_list: D007074:Immunoglobulin G; D012964:Sodium