The Relationship Between the “Adherence Starts with Knowledge-20” Questionnaire and Clinical Factors in Patients with COPD: A Multi-Center, Cross-Sectional Study

PURPOSE: Inhaler therapy is the mainstay of chronic obstructive pulmonary disease (COPD) management. Poor adherence causes disease exacerbation and affects patient mortality. Although the Adherence Starts with Knowledge-20 (ASK-20) questionnaire is a reliable tool for assessing medication adherence, the relationship between the ASK-20 and clinical factors in patients with COPD remains unknown. We investigated the relationship between the ASK-20 and clinical factors, and assessed real-world inhaler therapy use. PATIENTS AND METHODS: A multicenter, cross-sectional study of outpatients with COPD undergoing inhaler treatment who completed the ASK-20 questionnaire was performed. We investigated COPD-related health status using the COPD Assessment Test (CAT), psychological status using the Hospital Anxiety and Depression Scale (HADS-anxiety and HADS-depression), respiratory function, patient satisfaction levels, and real-world inhaler therapy use. RESULTS: Of the total 319 patients, 87% were male with a median age of 74 years. Most patients had mild or moderate COPD, according to Global Initiative for Chronic Obstructive Lung Disease stage. The total ASK-20 scores correlated significantly with the CAT, HADS-anxiety, and HADS-depression scores (r = 0.27, 0.33, and 0.29, respectively, p < 0.01). Multivariable analysis showed that CAT and HADS-anxiety scores had an independent and significant impact on the ASK-20 scores [β, standardized regression coefficient: 0.18 (95% CI, 0.03–0.35; p = 0.02), and 0.29 (95% CI, 0.17–0.42; p < 0.01), respectively]; however, the ASK-20 scores were not correlated with age, sex, body mass index, cohabitation, modified Medical Research Council Dyspnea Scale score, pulmonary function, disease duration, number of COPD exacerbations per year, comorbidities, inhaler numbers, nor inhaler components. CONCLUSION: The ASK-20 scores in patients with COPD were significantly associated with CAT and HADS scores. In Japan, Respimat was prescribed to younger patients and patients with lower CAT scores. The ASK-20, a simple evaluation method, is useful for identifying clinical factors affecting adherence in patients with COPD.