OBJECTIVES: Poor control of day-to-day asthma symptoms has been associated with increased exacerbation risk and reduced health-related quality of life. Our objective was to quantify the relationship between Asthma Control Questionnaire (ACQ) scores and exacerbation rates, healthcare resource utilization (HCRU), and utility values in adults with moderate-to-severe asthma using data from a phase 3 asthma trial (CAPTAIN) for use in economic modeling analyses.
METHODS: CAPTAIN was a 24- to 52-week, phase 3, randomized controlled trial in adults (≥18 years) with inadequately controlled asthma (ACQ-6≥1.5) despite medium- to high-dose inhaled corticosteroid/long-acting beta-agonist maintenance therapy. We used patient-level data from the CAPTAIN intention-to-treat population regardless of treatment assignment (N=2,436). Negative binomial models were estimated for moderate and severe exacerbation rates using time-varying ACQ-7 score, prestudy inhaled corticosteroid dose, and severe exacerbation history as covariates. Poisson models were estimated for unscheduled HCRU rates (physician, urgent care, and emergency department visits) using time-varying ACQ-7 score as a covariate. For the utility analysis, Asthma Qualify of Life Questionnaire (AQLQ) responses were mapped onto Asthma Quality of Life–5 Dimensions (AQL-5D) responses, to which a published time trade-off valuation was applied, and a fractional polynomial model for AQL-5D utility values was estimated using time-varying ACQ-7 as a covariate.
RESULTS: In our analysis, each 1-point increase in ACQ-7 score was associated with 34.3% and 52.4% increases in annualized moderate and severe exacerbation rates, respectively, and 34.1%, 41.2%, and 89.0% increases in annualized physician, urgent care, and emergency department visit rates, respectively. Utility values from the AQLQ/AQL-5D analysis ranged from 0.982 to 0.540 across the ACQ-7 range (0.14-4.71) observed at baseline.
CONCLUSIONS: This study quantifies the relationship between poorer symptom control ( measured by ACQ-7) and worse exacerbation, HCRU, and utility outcomes in a moderate-to-severe asthma population. Our results may support future economic evaluations in asthma.
FUNDING: GSK (206918, HO-17-17257)
