The Asthma Control Test as a predictive tool for hospitalization and death

<bold>Background:</bold> The Asthma control test (ACT) is a valid instrument to identify patients with uncontrolled asthma. However, studies on the ACT as a predictive tool for serious adverse outcomes are lacking. <bold>Aim:</bold> To study uncontrolled asthma and the association with future hospitalization and death. <bold>Methods:</bold> In 2015 to 2020 (index date), 89 959 adult asthma patients with a registered ACT score were identified in the Swedish National Airway Register. Patients were followed from index date until death or end of study period December 2022 whichever occurred first. Uncontrolled asthma was defined as ACT <20, and very poorly controlled asthma as ACT ≤15. The outcomes, overall hospitalization, and mortality, were obtained from the National Patient Register and the Swedish Cause of Death Register, identified by ICD codes. <bold>Results:</bold> In total, 38364 patients (44%) had uncontrolled asthma, and of these were 18338 (48%) very poorly controlled. Female sex, younger age, higher BMI, and lower lung function were more common among patients with uncontrolled asthma than those with controlled asthma. In multivariable logistic regression analyses adjusted for sex, age, previous treatment for cardiovascular disease and dose of inhaled corticosteroids, uncontrolled asthma was associated with all cause hospitalization (OR 1.31 95% CI 1.27-1.35) and all cause death (OR 1.42, 95% CI 1.28-1.54). Very poorly controlled asthma yielded even higher odds (OR 1.48, 95% CI 1.42-1.53), and (OR 1.58, 95% CI 1.41-1.79), respectively. <bold>Conclusion:</bold> Using the ACT cut off <20 is valuable to identify asthma patients at risk for hospitalization and death. Patients with an ACT score of ≤15 had an even higher risk for adverse outcomes.