A new tool for monitoring asthma outcomes: the ITG Asthma Short Form.
BACKGROUND
Asthma treatment has broadened from managing clinical markers to incorporate factors that are most meaningful to patients, collectively called health-related quality of life (HQL).


OBJECTIVE
To develop an asthma-specific HQL tool, meeting demands for brevity, usefulness and measurement precision.


METHODS
The 20-item Sydney Asthma Quality of Life Questionnaire (AQLQ) and six additional items were studied using factor analysis, reliability and validity tests among asthma patients 14 and older.


RESULTS
The 15-item Integrated Therapeutics Group Asthma Short Form (ITG-ASF) retains the validity of the AQLQ with improved scaling properties and interpretability. The ITG-ASF yields 6 scores: Symptom-Free Index, Functioning with Asthma, Psychosocial Impact of Asthma, Asthma Energy and Asthma-Confidence in Health and a Total. All items correlated 0.40 or higher with their hypothesized scales and passed discriminant validity tests, with scaling success rates from 75 to 100%. Reliability exceeded the minimum of 0.70 for group comparisons. Ceiling and floor effects were acceptable. Scales were valid in relation to changes in asthma severity and lung function. The best predictor of asthma severity (National Asthma Education and Prevention Program (NAEPP) staging) was the Symptom-Free Index. A Spanish translation is available, Chinese-American is forthcoming. The reading grade level is 4.8.


CONCLUSIONS
Development of the ITG-ASF was a data-driven process maximizing measurement precision and breadth while minimizing burden. The ITG-ASF is a brief, comprehensive and empirically valid tool that complements traditional markers of the outcomes of asthma care.
Bayliss
M S
MS
QualityMetric, Inc., Lincoln, RI, USA. mbayliss@qmetric.com
Espindle
D M
DM
Buchner
D
D
Blaiss
M S
MS
Ware
J E
JE
D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000534:rehabilitation*; D005163:Factor Analysis, Statistical; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics / Q000379:methods; D011788:Quality of Life; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D014481:United States