Asthma diagnosis and treatment
Asthma Control Test: Reliability, validity, and responsiveness in patients not previously followed by asthma specialists

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Background

The development of the Asthma Control Test (ACT), a short, simple, patient-based tool for identifying patients with poorly controlled asthma, was recently described in patients under the routine care of an asthma specialist.

Objectives

We sought to evaluate the reliability and validity of the ACT in a longitudinal study of asthmatic patients new to the care of an asthma specialist.

Methods

Patients (n = 313) completed the ACT and the Asthma Control Questionnaire (ACQ) at 2 physician visits (4-12 weeks apart). Pulmonary function was measured, and asthma specialists rated asthma control.

Results

Internal consistency reliability of the ACT was 0.85 (baseline) and 0.79 (follow-up). Test-retest reliability was 0.77. Criterion validity was demonstrated by significant correlations between baseline ACT scores and baseline specialists' ratings of asthma control (r = 0.52, P < .001) and ACQ scores (r = −0.89, P < .001). Discriminant validity was demonstrated, with significant (P < .001) differences in mean ACT scores across patients differing in asthma control, pulmonary function, and treatment recommendation. Responsiveness of the ACT to changes in asthma control and lung function was demonstrated with significant correlations between changes in ACT scores and changes in specialists' ratings (r = 0.44, P < .001), ACQ scores (r = −0.69, P < .001), and percent predicted FEV1 values (r = 0.29, P < .001). An ACT score of 19 or less provided optimum balance of sensitivity (71%) and specificity (71%) for detecting uncontrolled asthma.

Conclusions

The ACT is reliable, valid, and responsive to changes in asthma control over time in patients new to the care of asthma specialists. A cutoff score of 19 or less identifies patients with poorly controlled asthma.

Clinical implications

In a clinical setting the ACT should be a useful tool to help physicians identify patients with uncontrolled asthma and facilitate their ability to follow patients' progress with treatment.

Section snippets

ACT survey

The ACT survey is a patient-completed questionnaire with 5 items assessing asthma symptoms (daytime and nocturnal), use of rescue medications, and the effect of asthma on daily functioning (Fig 1). Each item includes 5 response options corresponding to a 5-point Likert-type rating scale. In scoring the ACT survey, responses for each of the 5 items are summed to yield a score ranging from 5 (poor control of asthma) to 25 (complete control of asthma). Details of the development of the ACT are

Sample

The number of patients participating in the study was 313. The mean age of the patients was 35 years (SD, 15.3), with a range of 12 to 84 years. At the baseline visit, specialists rated asthma control as well controlled or completely controlled in 48% of the 301 patients for whom data were available, somewhat controlled in 29% of the patients, and poorly controlled or not controlled at all in 23% of patients. The mean percent predicted FEV1 value at the baseline visit for the 301 patients for

Discussion

A cornerstone of the NAEPP guidelines for managing asthma is the ongoing assessment of asthma control, which is crucial for optimizing care and reducing the humanistic, economic, and societal burdens of the disease. Data suggest that patients with asthma and their physicians often overestimate the degree to which asthma is controlled.12 Overestimation of asthma control can result in failure to use needed interventions or to make necessary adjustments to medication regimens; the lack of

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    The research described in this article was funded by GlaxoSmithKline.

    Disclosure of potential conflict of interest: M. Schatz has received grants–research support from GlaxoSmithKline and Sanofi-Aventis and is on the speakers' bureau for AstraZeneca and Merck. C. A. Sorkness has consultant arrangements with GlaxoSmithKline and AstraZeneca, has received grants–research support from GlaxoSmithKline, and is on the speakers' bureau for GlaxoSmithKline and Genentech. J. T. Li has had consultant arrangements with GlaxoSmithKline and has received grants–research support from GlaxoSmithKline. P. Marcus has consultant arrangements with Altana, has received grants–research support from GlaxoSmithKline and AstraZeneca, and is on the speakers' bureau for GlaxoSmithKline, Genentech, Novarits, Merck, and Aventis. J. J. Murray has consultant arrangements with GlaxoSmithKline, has received grants–research support from GlaxoSmithKline, and is on the speakers' bureau for GlaxoSmithKline. R. A. Nathan has consultant arrangements with Amgen, Altana, AstraZeneca, Aventis, Genentech, GlaxoSmithKline, Merck, Novartis, Pfizer, Schering/Key, Sepracor, and Viropharm; has received grants–research support from Abbot, Altana, Aventis, AstraZeneca, Bayer, Berlex, Boehringer Ingelheim, Bristol-Myers Squibb, Ciba-Geigy, Dura, Forest, GlaxoSmithKline, Immunex, Janssen, Parke-Davis, Pfizer, 3-M Pharmaceuticals, Proctor & Gamble, Roberts, Sandoz, Sanofi, Schering/Key, Sepracor, Sterling, Tap Pharmaceuticals, Wallace, and Wyeth; and is on the speakers' bureau for AstraZeneca, Aventis, Genentech/Novartis, GlaxoSmithKline, Pfizer, and Schering/Key. M. Kosinski—none declared. T. B. Pendergraft is employed by GlaxoSmithKline. P. Jhingran has stock or other equity ownership in and is employed by GlaxoSmithKline.

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