title: The Childhood Asthma Control Test: retrospective determination and clinical validation of a cut point to identify children with very poorly controlled asthma.
abstract: BACKGROUND
  The Childhood Asthma Control Test (C-ACT) has demonstrated validity in classifying children aged 4 to 11 years as having either "well-controlled" or "not well-controlled" asthma. However, new asthma management guidelines distinguish 3 levels of asthma control.
  
  
  OBJECTIVE
  We sought to determine a second cut point on the C-ACT to identify children with "very poorly controlled" asthma.
  
  
  METHODS
  Binomial logistic regression was performed on data from 671 children. The specialist's rating of control was the criterion measure. Specialists' severity ratings, specialists' assessment of therapy, and FEV(1) percent predicted were used to assess the clinical validity of the cut point.
  
  
  RESULTS
  A cut point of 12 was selected because it correctly classified the highest percentage of participants (66.3%) as having "very poorly controlled" (vs "not well controlled") asthma and demonstrated high specificity (89.8%) and moderate positive predictive value (69.1%). Children scoring 12 or less versus 13 to 19 had lower mean FEV(1) percent predicted (79.8% vs 92.6%, P = .0002) and were more frequently stepped up in therapy (72.9% vs 53.6%, P = .0131) and rated as having severe asthma (13.6% vs 4.5%, P = .0005). One month later, significant differences in C-ACT scores and lung function between these 2 groups persisted. The mean C-ACT score of participants classified as "very poorly controlled" was significantly lower than that of participants classified as "not well-controlled" (17.2 vs 20.3, respectively; P = .0001).
  
  
  CONCLUSIONS
  A second cut point of 12 or less on the C-ACT identifies children with the lowest level of control, who are at risk for poorer outcomes, and is conceptually consistent with the classification of "very poorly controlled" asthma adopted by asthma management guidelines.
authors.affiliation: National Jewish Health and University of Colorado School of Medicine, Pediatrics/Allergy & Immunology, Denver, CO 80206-2762, USA. LiuA@NJHealth.org
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Liu
authors.forename: Robert S
authors.initials: RS
authors.lastname: Zeiger
authors.forename: Christine A
authors.initials: CA
authors.lastname: Sorkness
authors.forename: Nancy K
authors.initials: NK
authors.lastname: Ostrom
authors.forename: Bradley E
authors.initials: BE
authors.lastname: Chipps
authors.forename: Kathleen
authors.initials: K
authors.lastname: Rosa
authors.forename: Maria E
authors.initials: ME
authors.lastname: Watson
authors.forename: Michael S
authors.initials: MS
authors.lastname: Kaplan
authors.forename: John R
authors.initials: JR
authors.lastname: Meurer
authors.forename: Todd A
authors.initials: TA
authors.lastname: Mahr
authors.forename: Michael S
authors.initials: MS
authors.lastname: Blaiss
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Piault-Louis
authors.forename: Jeffrey
authors.initials: J
authors.lastname: McDonald
mesh_terms: D001249:Asthma / Q000503:physiopathology* / Q000628:therapy*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D017410:Practice Guidelines as Topic; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013997:Time Factors