Measuring Asthma Control

Abstract

Daily symptom, peak expiratory flow rate (PEFR), and medication diaries are often used in clinical trials of treatments for asthma on the assumption that they provide a better estimate of clinical status than does a questionnaire completed in the clinic. We conducted a study with the aim of comparing the measurement properties of the clinic-completed Asthma Control Questionnaire with those of the Asthma Control Diary. The diary is composed of questions and response options almost identical to those of the questionnaire, but uses PEFR instead of FEV(1) as the measure of airway caliber. In an observational study, 50 adults with symptomatic asthma attended a McMaster University asthma clinic at 0, 1, 5, and 9 wk to complete the Asthma Control Questionnaire and other measures of asthma status. For 1 wk before each follow-up visit, patients completed the Asthma Control Diary every morning and evening. Concordance between the questionnaire and diary was high (intraclass correlation coefficient [ICC] = 0.87). Both reliability (ICC: questionnaire = 0.90; diary = 0.86) and responsiveness (responsiveness index: questionnaire = 1.06; diary = 0.90; p = 0.005) were better with the questionnaire than with the diary. Correlations between the two instruments and other measures of clinical asthma status were similar and close to a priori predictions. Both the Asthma Control Questionnaire and the Asthma Control Diary are valid instruments for measuring asthma control, but the questionnaire has slightly better discriminative and evaluative measurement properties than does the diary.

Asthma outcomes: Symptoms

“…4, 43 The disadvantages of electronic diaries include the costs of handheld devices (as high as hundreds of dollars per unit), the need for user-friendly interfaces for data entry and download, equipment malfunction, and availability and adequacy of technical support. Because evidence is insufficient to indicate that daily diary data are superior to interval questionnaires 44 and because of potential disadvantages of electronic diaries compared with paper-and-pencil versions of daily diaries, we do not advocate their routine use in studies of asthma at the present time. Decisions regarding the use of electronic diaries should be made by investigators in light of the research objectives and resources available to complete the studies.…”

Lessons Learned for the Study of Childhood Asthma from the Centers for Children’s Environmental Health and Disease Prevention Research

“…Juniper et al (1996, 2000) developed a series of questions to assess the effect of symptoms on a child’s quality of life. These provide a composite assessment of disease activity and tend to correlate better with daily lung function measures than do symptom questionnaires.…”

Changes in Exhaled Nitric Oxide and Breath pH during Fluticasone Wean in Asthma

“…Two measurements have received particular attention: the fraction of expired nitric oxide (F ENO ) [6,7,8,9] and exhaled breath condensate (EBC) pH [10,11,12]. F ENO is high in patients with allergic asthma and generally decreases with ICS therapy; it is likely to be a useful adjunct to symptoms analysis in ICS dose titration [6,7,8,13,14]. Breath condensate pH is low during acute asthma exacerbations and increases with corticosteroid dosing [10].…”