Longitudinal validation of a tool for asthma self-monitoring.
OBJECTIVE
To establish longitudinal validation of a new tool, the Asthma Symptom Tracker (AST). AST combines weekly use of the Asthma Control Test with a color-coded graph for visual trending.


METHODS
Prospective cohort study of children age 2 to 18 years admitted for asthma. Parents or children (n = 210) completed baseline AST assessments during hospitalization, then over 6 months after discharge. Concurrent with the first 5 AST assessments, the Asthma Control Questionnaire (ACQ) was administered for comparison.


RESULTS
Test-retest reliability (intraclass correlation) was moderate, with a small longitudinal variation of AST measurements within subjects during follow-ups. Internal consistency was strong at baseline (Cronbach's α 0.70) and during follow-ups (Cronbach's α 0.82-0.90). Criterion validity demonstrated a significant correlation between AST and ACQ scores at baseline (r = -0.80, P < .01) and during follow-ups (r = -0.64, -0.72, -0.63, and -0.69). The AST was responsive to change over time; an increased ACQ score by 1 point was associated with a decreased AST score by 2.65 points (P < .01) at baseline and 3.11 points (P < .01) during follow-ups. Discriminant validity demonstrated a strong association between decreased AST scores and increased oral corticosteroid use (odds ratio 1.13, 95% confidence interval, 1.10-1.16, P < .01) and increased unscheduled acute asthma visits (odds ratio 1.23, 95% confidence interval, 1.18-1.28, P < .01).


CONCLUSIONS
The AST is reliable, valid, and responsive to change over time, and can facilitate ongoing monitoring of asthma control and proactive medical decision-making in children.
Primary Children's Medical Center, Division of Pediatric Inpatient Medicine, University of Utah School of Medicine, 100 North Medical Dr, Salt Lake City, UT 84113. flory.nkoy@hsc.utah.edu.
Flory L
FL
Nkoy
Bryan L
BL
Stone
Bernhard A
BA
Fassl
Derek A
DA
Uchida
Karmella
K
Koopmeiners
Sarah
S
Halbern
Eun H
EH
Kim
Allison
A
Wilcox
Jian
J
Ying
Tom H
TH
Greene
David M
DM
Mosen
Michael N
MN
Schatz
Christopher G
CG
Maloney
D000293:Adolescent; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy / Q000628:therapy; D002648:Child; D002675:Child, Preschool; D003661:Decision Support Techniques; D018450:Disease Progression; D016903:Drug Monitoring; D005260:Female; D006760:Hospitalization; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires
D018927:Anti-Asthmatic Agents
asthma control; pediatrics; self-management; self-monitoring