Variation in process quality measures of diabetes care by region and institution in Japan during 2015–2016: An observational study of nationwide claims data

Aims: To calculate process quality measures of diabetes care in Japan using nationwide exclusive claims database. Methods: Using the National Database of health insurance claims during 2015–2016, the proportions of outpatients who received recommended examinations at least annually among those with regular antidiabetic medication were calculated as quality indicators, reported altogether and by prefecture and institutional certification (from the Japan Diabetes Society). Distributions of institutional-level quality indicators were also reported. Results: Among 4,154,452 outpatients, 96.7% underwent HbA1c or glycated albumin examination. Retinopathy examination was conducted among 46.5% of patients [prefecture (range): 37.5%–51.0%, institutional certification: 44.8% (without) vs. 59.8% (with)]. Urinary qualitative examination was conducted among 67.3% of patients at institutions with <200 beds (prefecture: 54.1%–81.9%, institutional certification: 66.8% vs. 92.8%), whereas urinary quantitative albumin or protein examination was conducted among 19.4% of patients (prefecture: 10.8%–31.6%, institutional certification: 18.7% vs. 54.8%). Distributions of institutional-level quality indicators showed that most institutions without institutional certification seldomly order urinary quantitative examination. Conclusions: Although the quality indicator for glycaemic control examination was favourable, some aspects of diabetes care were suboptimal and varied greatly by prefecture and institution; individual and organisational efforts to improve quality of diabetes care would be needed in Japan.