Relationship Between Asthma Control Status and Health-Related Quality of Life in Japan: A Cross-Sectional Mixed-Methods Study.

Abstract

There is limited information regarding multidimensional relationships between asthma control and health-related quality of life (HRQoL), work productivity, and asthma symptom burden in Japan. Furthermore, systematic qualitative investigations about asthma burden have not been performed. This cross-sectional, mixed-methods study included Japanese patients (≥ 20years) with asthma adherent to inhaled corticosteroids/long-acting β2-agonists (ICS/LABA). The primary endpoint was impact of asthma on HRQoL, measured using the Asthma Health Questionnaire-33 (AHQ-33). Secondary endpoints were cough burden (Japanese-adapted Leicester Cough Questionnaire [J-LCQ]) and impact of asthma on work/activities (asthma-specific Work Productivity and Activity Impairment Questionnaire [WPAI:Asthma]). Quantitative data were assessed for the overall population and for well-controlled (WC) and not well-controlled (NWC) asthma subgroups. Qualitative verbal interviews further assessed the impact of NWC asthma on patients' HRQoL; emergent themes were extracted using thematic analyses. Of 454 patients, 45.2% (n = 205) had NWC asthma. Patients with NWC asthma had significantly worse asthma- and cough-related HRQoL across all AHQ-33 and J-LCQ domains and significantly greater work and activity impairment versus patients with WC asthma, across all assessed WPAI:Asthma domains. AHQ-33 total score was highly correlated with J-LCQ total and domain scores (r = -0.8132 to r = -0.7407). Nine themes emerged from qualitative interviews and confirmed that patients with NWC asthma had considerable HRQoL impairment due to asthma symptoms. Patients with NWC asthma had higher symptom burden and worse HRQoL than patients with WC asthma, despite ICS/LABA adherence. Cough burden correlated with HRQoL, suggesting cough may be one of the key markers to inform treatment strategy for patients with asthma.