Adherence to dipeptidyl peptidase‐4 inhibitor therapy among type 2 diabetes patients with employer‐sponsored health insurance in Japan

AIMS/INTRODUCTION Dipeptidyl peptidase-4 inhibitors (DPP-4i) are a common first-line treatment for type 2 diabetes in Japan. However, little is known about patients' medication adherence, persistence and discontinuation in this setting. MATERIALS AND METHODS This was a retrospective cohort study of new DPP-4i users in a Japanese claims database. Adult patients (age 18-65 years) with type 2 diabetes diagnosis and no diagnosis of other diabetes or pregnancy during the study period were included if they were prescribed a DPP-4i as monotherapy or combination oral therapy. Adherence to therapy was measured using the proportion of days covered method over a fixed period of 1 year. The proportion of days covered of ≥80% was considered adherent. Persistence was defined as continuing index DPP-4i treatment with <90-day gap between refills. Patient baseline characteristics were explored as potential predictors of DPP-4i discontinuation and adherence in multivariable models. RESULTS The final sample contained 2,874 monotherapy and 3,016 dual therapy patients. The mean age was approximately 51 years, and 75% were men. The mean proportion of days covered was 76.6% among monotherapy patients and 82.5% among dual therapy patients, with 67.2% of monotherapy and 74.4% of dual therapy patients classified as adherent. At 12 months, 72.2% of monotherapy and 79.2% of dual therapy patients were persistent. In adjusted models, younger age and having fewer concomitant medications were significantly associated with lower adherence and higher discontinuation, in both treatment groups. CONCLUSIONS Those under the age of 45 years, and those with fewer concomitant medications were less likely to be adherent and persistent, and more likely to discontinue DPP-4i therapy.