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.