A structured review evaluating content validity of the Asthma Control Test, and its consistency with US guidelines and patient expectations for asthma control

Objective To assess whether the content of the Asthma Control Test (ACT) served as a valid measure of asthma control (i.e., content validity) by mapping ACT items to the National Heart, Lung and Blood Institute (NHLBI) guideline asthma control definitions, and to language used by patients to describe their asthma. Data sources PubMed and EMBASE databases were used for a structured literature analysis. Study selections Full-text, English-language articles that reported findings from qualitative studies conducted in adults, focusing on patient descriptors of asthma symptoms, impacts, or severity, were included. Pediatric studies, studies conducted in patients without asthma, and studies that did not contain qualitative data were excluded. Results ACT items reflected all domains of asthma impairment described in the NHLBI guidelines, except pulmonary function. Following the literature review, 28 full-text publications were identified that included patient descriptors that could be mapped to ACT items. For example, per ACT Item 1, patients described having trouble at work, school, and completing household chores; and, per ACT Item 2, patients used the phrase "short of breath" to describe asthma-associated symptoms. Conclusion ACT item content corresponded well with the NHLBI guideline definitions of the impairment domain of asthma control (focused on asthma symptoms and impact), and we identified numerous examples in the literature indicating that ACT concepts and item content mirror the language patients use when discussing asthma symptoms and impact, and their degree of asthma control. This provides further evidence to support content validity of the ACT as a measure of asthma control.