title: Mathematical weighting of the pediatric Crohn's disease activity index (PCDAI) and comparison with its other short versions.
abstract: BACKGROUND
  The Pediatric Crohn's Disease Activity Index (PCDAI) has become the standard outcome measure in pediatric Crohn's disease (CD) clinical research. Other versions have been proposed but without systematic evaluation. The aim was to assess validity and responsiveness of the abbreviated PCDAI (abbrPCDAI), short PCDAI (shPCDAI), and modified PCDAI (modPCDAI) as measures of disease activity and to compare these with a mathematically weighted version developed here (wPCDAI).
  
  
  METHODS
  The raw data from four prospectively collected datasets were used, totaling 437 children with CD (including two clinical trials). Discriminant validity utilized physician global assessment of disease activity (PGA), and construct validity the correlation with PGA and laboratory results. Feasibility and face validity were ascertained by a survey of 33 experts in pediatric CD.
  
  
  RESULTS
  The wPCDAI had better performance than the PCDAI in construct validity and responsiveness and it discriminated better between the disease activity categories (area under the receiver operator characteristic [ROC] 0.97; 95% confidence interval [CI]: 0.95-0.99). In comparison to the original PCDAI, the noninvasive versions (abbrPCDAI and shPCDAI) had lower face, construct, and discriminant validity but were judged to be significantly more feasible. The modPCDAI performed well in the construct validation but was consistently inferior in all other parameters. Cutoffs that correspond to remission, response, and gradations of disease activity were determined for each index.
  
  
  CONCLUSIONS
  The newly weighted wPCDAI performed better than the original PCDAI and is more feasible. The noninvasive versions (shPCDAI and abbrPCDAI) are inferior to the full PCDAI, but when needed in retrospective studies either may be equally used.
authors.affiliation: Pediatric Gastroenterology Unit, Shaare Zedek Medical Center, Hebrew University of Jerusalem, Israel. turnerd@szmc.org.il
authors.forename: Dan
authors.initials: D
authors.lastname: Turner
authors.forename: Anne M
authors.initials: AM
authors.lastname: Griffiths
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Walters
authors.forename: Tong
authors.initials: T
authors.lastname: Seah
authors.forename: James
authors.initials: J
authors.lastname: Markowitz
authors.forename: Marian
authors.initials: M
authors.lastname: Pfefferkorn
authors.forename: David
authors.initials: D
authors.lastname: Keljo
authors.forename: Jacob
authors.initials: J
authors.lastname: Waxman
authors.forename: Anthony
authors.initials: A
authors.lastname: Otley
authors.forename: Neal S
authors.initials: NS
authors.lastname: LeLeiko
authors.forename: David
authors.initials: D
authors.lastname: Mack
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Hyams
authors.forename: Arie
authors.initials: A
authors.lastname: Levine
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003424:Crohn Disease / Q000473:pathology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008432:Mathematical Computing; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D055815:Young Adult