Characterization of low adherence population in asthma patients from Japan using Adherence Starts with Knowledge-12

Adherence Starts with Knowledge-12 (ASK-12) is a useful indicator of drug adherence. In this study, we analyzed patient background including social and psychological factors in a low-adherence group of patients with asthma defined using ASK-12.

From a questionnaire survey for patients with asthma from the Niigata Prefecture, Japan, conducted in the fall of 2016, we enrolled patients who answered all ASK-12 items and underwent a measured respiratory function test within 1 year. The low-adherence group (ASK-12 ≥ 28) was compared with the control group (ASK-12 < 28), and we conducted a cluster analysis of the low-adherence group.

There were 170 patients in the low-adherence group and 402 patients in the control group. There was a significant difference between age, gender, working status, smoking history, the percentage of forced expiratory volume in one second (%FEV₁), asthma control test (ACT), and Patient Health Questionnaire-9 (PHQ-9) score between the two groups. Logistic analysis revealed that working status (working), % FEV₁ (<90%), and PHQ-9 score (>5) were independent factors for the low-adherence group. The cluster analysis identified three clusters in the low-adherence group. Among these, one cluster was characterized by elderly males with chronic obstructive pulmonary disease and another by middle-aged nonsmoking females with a depression tendency, had problems with asthma control.

Several factors were considered to be attributed to low drug-adherence. There were several phenotypes in the low-adherence population correlated with incomplete asthma control. Intervention with drug adherence should be a future goal for asthma treatment.