title: Monitoring childhood asthma: web-based diaries and the asthma control test.
abstract: BACKGROUND
  Data from asthma diaries are frequently used as an end point in asthma studies; however, data on the validity of Web-based diaries are scarce.
  
  
  OBJECTIVE
  First, we examined the validity of a Web-based diary in assessing asthma control. Second, we determined the cutoff points for well-controlled asthma of the Childhood Asthma Control Test (C-ACT) and the Asthma Control Test (ACT), and calculated the minimal important difference for both tests.
  
  
  METHODS
  Children with asthma, ages 4-18 years (n = 228) completed a 4-week Web-based diary, C-ACT, ACT, and an asthma-related quality-of-life questionnaire at baseline and after 1-year follow-up.
  
  
  RESULTS
  The completion rate of the Web-based diaries was 89%. The diary scores correlated strongly with C-ACT and ACT scores (r = -0.73, P < .01; r = -0.64, P < .01, respectively) and the changes in diary scores correlated well with changes in C-ACT and ACT scores. The best cutoff points for well-controlled asthma were C-ACT ≥ 22 and ACT ≥ 23. The minimal important differences were 1.9 (95% CI, 1.3-2.5) for ACT and 1.6 (95% CI, 1.1-2.1) for C-ACT, and -0.7 points/d (95% CI, -1.1 to -0.4) for the Web-based diary.
  
  
  CONCLUSIONS
  Our Web-based diary was valid for recording asthma symptoms. Cutoff points of ≥22 (C-ACT) and ≥23 (ACT) define well-controlled asthma. We recommend a 2 C-ACT and ACT points difference as minimally important.
authors.affiliation: Department of Pediatric Pulmonology, Erasmus University Medical Centre - Sophia Children's Hospital, Rotterdam, The Netherlands.
authors.forename: Sandra
authors.initials: S
authors.lastname: Voorend-van Bergen
authors.affiliation: Department of Pediatrics, Amphia Hospital, Breda, The Netherlands.
authors.forename: Anja A
authors.initials: AA
authors.lastname: Vaessen-Verberne
authors.affiliation: Department of Pediatrics, Rijnstate Hospital, Arnhem, The Netherlands.
authors.forename: Anneke M
authors.initials: AM
authors.lastname: Landstra
authors.affiliation: Department of Pediatrics, Catharina Hospital, Eindhoven, The Netherlands.
authors.forename: Hein J
authors.initials: HJ
authors.lastname: Brackel
authors.affiliation: Department of Pediatrics, Flevo Hospital - De Kinderkliniek, Almere, The Netherlands.
authors.forename: Norbert J
authors.initials: NJ
authors.lastname: van den Berg
authors.affiliation: Department of Pediatric Pulmonology, Erasmus University Medical Centre - Sophia Children's Hospital, Rotterdam, The Netherlands.
authors.forename: Daan
authors.initials: D
authors.lastname: Caudri
authors.affiliation: Department of Pediatric Pulmonology, Erasmus University Medical Centre - Sophia Children's Hospital, Rotterdam, The Netherlands.
authors.forename: Johan C
authors.initials: JC
authors.lastname: de Jongste
authors.affiliation: Department of Pediatric Pulmonology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Merkus
authors.affiliation: Department of Pediatric Pulmonology, Erasmus University Medical Centre - Sophia Children's Hospital, Rotterdam, The Netherlands. Electronic address: m.pijnenburg@erasmusmc.nl.
authors.forename: Mariëlle W
authors.initials: MW
authors.lastname: Pijnenburg
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D045853:Exhalation; D005260:Female; D055991:Health Records, Personal; D006801:Humans; D020407:Internet; D008297:Male; D009569:Nitric Oxide / Q000032:analysis; D010349:Patient Compliance; D011788:Quality of Life; D012129:Respiratory Function Tests; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
chemical_list: D009569:Nitric Oxide
keywords: Asthma; GINA; Internet diaries; asthma diaries; asthma-related quality of life; childhood asthma control test; minimal important difference; pediatrics; validity