title: Ankylosing spondylitis antirheumatic drug trials. II. Tables for calculating sample size for clinical trials.
abstract: The calculation of sample size requires knowledge of the standard deviation (SD) of index variables. Unfortunately, there are no published lists of standard deviations and it is exceedingly difficult to locate variance estimates based on relevant populations. We used standardized procedures to determine in 60 patients with ankylosing spondylitis (AS) the SD of key outcome measures recommended in current Food Drug Administration and European League Against Rheumatism guidelines for AS clinical trials. We anticipate that these tables will be useful to clinical researchers in selecting outcome measures as well as for calculating sample size requirements for future clinical studies in AS.
authors.affiliation: Division of Rheumatology, University of Western Ontario, London, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Bellamy
authors.forename: W W
authors.initials: WW
authors.lastname: Buchanan
authors.forename: J M
authors.initials: JM
authors.lastname: Esdaile
authors.forename: A G
authors.initials: AG
authors.lastname: Fam
authors.forename: W F
authors.initials: WF
authors.lastname: Kean
authors.forename: J M
authors.initials: JM
authors.lastname: Thompson
authors.forename: G A
authors.initials: GA
authors.lastname: Wells
authors.forename: J
authors.initials: J
authors.lastname: Campbell
mesh_terms: D000704:Analysis of Variance; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D002986:Clinical Trials as Topic / Q000379:methods*; D006801:Humans; D012015:Reference Standards; D012107:Research Design; D013167:Spondylitis, Ankylosing / Q000188:drug therapy*
chemical_list: D000893:Anti-Inflammatory Agents