Asthma and lower airway disease
Development and validation of the Composite Asthma Severity Index—an outcome measure for use in children and adolescents

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Background

Asthma severity is reflected in many aspects of the disease, including impairment and future risks, particularly for exacerbations. According to the Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma, however, to assess more comprehensively the severity of asthma the level of current treatment needed to maintain a level of control should be included.

Objective

Development and validation of a new instrument, the Composite Asthma Severity Index (CASI), which can quantify disease severity by taking into account impairment, risk, and the amount of medication needed to maintain control. At present, there is no instrument available to measure and assess the multidimensional nature of asthma.

Methods

Twenty-six established asthma investigators, who are part of the National Institutes of Health–supported Inner City Asthma Consortium, participated in a modified Delphi consensus process to identify and weight the dimensions of asthma. Factor analysis was performed to identify independent domains of asthma by using the Asthma Control Evaluation trial. CASI was validated by using the Inner City Anti-IgE Therapy for Asthma trial.

Results

CASI scores include 5 domains: day symptoms and albuterol use, night symptoms and albuterol use, controller treatment, lung function measures, and exacerbations. At Asthma Control Evaluation trial enrollment, CASI ranged from 0 to 17, with a mean of 6.2. CASI was stable, with minimal change in variance after 1 year of treatment. In external validation, CASI detected a 32% larger improvement than did symptoms alone.

Conclusion

CASI retained its discriminatory ability even with low levels of symptoms reported after months of guidelines-directed care. Thus, CASI has the ability to determine the level of asthma severity and provide a composite clinical characterization of asthma.

Section snippets

Overview

There were 4 distinct steps in the development of CASI (Fig 1). First, the independent outcome domains of asthma were determined via factor analysis by using data from more than 500 children and adolescents in the Asthma Control Evaluation (ACE) trial. Second, 26 asthma experts made individual and group decisions as to how the components of these domains should be weighted and combined into a final CASI score. Third, the scale properties of CASI were evaluated. Finally, CASI was externally

Determining independent dimensions of asthma severity

The factor analysis revealed 5 independent domains of asthma among the 11 commonly employed asthma outcomes. Those domains were as follows: symptoms (combining days and nights of symptoms and days and nights of albuterol usage), controller medication usage (inhaled corticosteroids prescribed and long-acting β-agonists prescribed), lung function (FEV1 percent predicted and ratio of FEV1 to forced vital capacity), oral corticosteroid bursts, and unscheduled visits (including emergency department

Discussion

Unlike many instruments that measure only asthma control, CASI quantifies asthma severity by using multiple dimensions. By incorporating symptoms, exacerbations, lung function, and treatment requirements into a single index, CASI combines domains of impairment and future risk with the level of treatment needed to reach the current clinical state, and in doing so, addresses the need for a comprehensive asthma index that reflects disease severity. This measure of asthma severity provides a means

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  • Cited by (0)

    This project was funded in whole or in part with federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, under contract nos. NO1-AI-25496 and NO1-JAI-25482. Additional funds were provided by the National Center for Research Resources, National Institutes of Health, under grants RR00052, M01RR00533, 1UL1RR025771, M01RR00071, 1UL1RR024156, 5UL1RR024992-02, and 5M01RR020359-04.

    Disclosure of potential conflict of interest: M. Kattan and G. R. Bloomberg have received research support from the National Institute of Allergy and Infectious Diseases (NIAID)/National Institutes of Health (NIH). S. J. Szefer has consulted for GlaxoSmithKline, Genentech, Merck, Boehringer-Ingelheim, Novartis, and Schering-Plough and has received research support from GlaxoSmithKline, the National Heart, Lung, and Blood Institute (NHLBI), the National Institute of Environmental Health Sciences (NIEHS), the NIAID, the NIH, and the Environmental Protection Agency. R. A. Wood has consulted for the Asthma and Allergy Foundation of America, received research support from the NIH, and served on the medical advisory board for the Food Allergy and Anaphylaxis Network. A. H. Liu has received a speaker honorarium from Merck. J. A. Pongracic has received research support from the NIAID. J.F. Chmiel has received research support from the NIH. W. J. Morgan has consulted for the Cystic Fibrosis Foundation, Genentech, and Novartis and has received research support from the NIH and Novartis. W. W. Busse has served on advisory boards for Centocor and Merck; has consulted for Amgen, AstraZeneca, Novartis, GlaxoSmithKline, MedImmune, and Genentech; and has received research support from the NIAID/NHLBI/NIH. The rest of the authors declare that they have no relevant conflicts of interest.

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