Asthma Symptom Utility Index: Reliability, validity, responsiveness, and the minimal important difference in adult asthmatic patients - 31/10/12
Corresponding author: Robert A. Wise, MD, Johns Hopkins Asthma and Allergy Center–4B.72, Division of Pulmonary and Critical Care Medicine, 5501 Hopkins Bayview Circle, Baltimore, MD 21224.Abstract |
Background |
The evaluation of asthma symptoms is a core outcome measure in asthma clinical research. The Asthma Symptom Utility Index (ASUI) was developed to assess the frequency and severity of asthma symptoms. The psychometric properties of the ASUI are not well characterized, and a minimal important difference (MID) is not established.
Objectives |
We assessed the reliability, validity, and responsiveness to change of the ASUI in a population of adult asthmatic patients. We also sought to determine the MID for the ASUI.
Methods |
Adult asthmatic patients (n = 1648) from 2 previously completed multicenter randomized trials were included. Demographic information, spirometric results, ASUI scores, and other asthma questionnaire scores were obtained at baseline and during follow-up visits. Participants also kept a daily asthma diary.
Results |
The internal consistency reliability of the ASUI was 0.74 (Cronbach ⍺). Test-retest reliability was 0.76 (intraclass correlation). Construct validity was demonstrated by significant correlations between ASUI scores and Asthma Control Questionnaire scores (Spearman correlation r = −0.79; 95% CI, −0.85 to −0.75; P < .001) and Mini Asthma Quality of Life Questionnaire scores (r = 0.59; 95% CI, 0.51-0.61; P < .001). Responsiveness to change was demonstrated, with significant differences between mean changes in ASUI scores across groups of participants differing by 10% in percent predicted FEV1 (P < .001) and by 0.5 points in Asthma Control Questionnaire scores (P < .001). Anchor-based and statistical methods support an MID for the ASUI of 0.09 points.
Conclusions |
The ASUI is reliable, valid, and responsive to changes in asthma control over time. The MID of the ASUI (range of scores, 0-1) is 0.09.
Le texte complet de cet article est disponible en PDF.Key words : Asthma Symptom Utility Index, reliability, validity, responsiveness, minimal important difference
Abbreviations used : ACQ, AQLQ, ASUI, EPAC, MID, PEFR, SARA, SIIVA
Plan
| The Study of Acid Reflux and Asthma was supported by the National Institutes of Health (NIH)/National Heart, Lung, and Blood Institute (NHLBI; 5U01HL072968) and the American Lung Association and is registered at clinicaltrials.gov as NCT00069823. The Safety of Inactivated Influenza Vaccine in Asthma trial was supported by grants from the American Lung Associations of Alabama, Central Florida, Colorado, Delaware, Eastern Missouri, Finger Lakes (New York), Georgia, Gulfcoast Florida, Hudson Valley (New York), Illinois, Indiana, Louisiana, Maine, Metropolitan Chicago, Michigan, Mid-Ohio, Minnesota, Nashua–Suffolk (New York), New Hampshire, New York City, North Carolina, Northeast Florida, Ohio, Oklahoma, Pennsylvania, South Florida, Southeast Florida, Texas, Vermont, Western Missouri, Wisconsin, Greater Norfolk County (Massachusetts), Hawaii, Middlesex County (Massachusetts), New York State, Northern Rockies, Queens (New York), Western Massachusetts, and Virginia; Baylor College of Medicine; the Thalheim Family; Duke University; the Ernest N. Morial Asthma, Allergy, and Respiratory Disease Center; the Merck Foundation; and GlaxoSmithKline. |
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| Disclosure of potential conflict of interest: C. Bime has received support for travel from the American Lung Association. J. T. Holbrook has been supported by one or more grants from and has received support for travel from the American Lung Association and has received one or more payments for lecturing from or is on the speakers’ bureau for ARVO and the American Thoracic Society. M. M. Sockrider has received grants and support for travel from the American Lung Association and has received one or more grants from or has one or more grants pending with the National Heart, Lung, and Blood Institute. R. A. Wise is a member of the Clinical Endpoint Committee for GlaxoSmithKline, the Data and Safety Monitoring Board (SC) for BIPI, the Mortality Review Committee for Mylan, the Scientific Advisory Board for AstraZeneca, the Steering Committee for Spiration, and the Scientific Advisory Board for Sunovion and has received one or more grants from or has one or more grants pending with BIPI, Merck, and GlaxoSmithKline. The rest of the authors declare that they have no relevant conflicts of interest. |
Vol 130 - N° 5
P. 1078-1084 - novembre 2012 Retour au numéro
Article précédent
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- Correction
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