The association between control level and self-reported treatment adherence across different treatment types in Japanese asthma patients

Abstract

Background: Poor control of asthma symptoms is associated with a higher asthma disease burden, and asthma medication adherence is a known predictor for a better control status. This study sought to describe the current asthma control status, self-reported treatment adherence, and the association between them, as well as to describe how control level and better adherence impact the health outcomes of asthma patients.

Methods: This study used cross-sectional data from the 2018 Japan National Health and Wellness Survey (NHWS). Asthma control status and adherence were assessed using the Asthma Control Test (ACT) and Morisky Medication Adherence Scale-8 (MMAS-8), respectively. Asthma treatment and patients' health outcomes, i.e. health-related quality of life (HRQoL) and work productivity, were self-reported. Asthma control and self-reported treatment adherence were analyzed descriptively, and the association was investigated by comparing mean ACT scores across adherence levels. Health outcomes were compared across control and adherence levels by multivariate analyses.

Results: A total of 816 patients had a physician diagnosis of asthma, with 67.0% reporting at least well controlled (ALWC). Of 505 asthma patients receiving prescription medication, half reported low adherence to medication use. Among asthma patients reporting high adherence, 35.6% were not well controlled (NWC). After adjusting for covariates, NWC asthma patients had significantly worse health outcomes than ALWC patients.

Conclusions: One-third of asthma patients in Japan suffer from poorly controlled asthma. Results of the 2018 NHWS show that poor control status negatively affects patients' HRQoL and work productivity, suggesting an unmet need for better treatments to lessen the burden of asthma.

Keywords: Asthma; Asthma control status; Asthma treatment; Humanistic burden; Treatment adherence.