Quality of care for diabetes patients using National Health Insurance claims data in Japan

Background Assessment of the quality of care is a key element in current diabetes care. However, the quality of care for diabetes patients in Japan has rarely been reported. Objectives To assess the quality of diabetes care in two communities in Japan by using National Health Insurance claims data. Methods We analysed claim data of 13 650 beneficiaries of National Health Insurance in two communities in Japan from May 2006 to April 2007. Diabetes cases were identified by using a case detection algorism. Our main outcome measures were three process quality indicators: (1) haemoglobin A1c (HbA1c) testing; (2) annual eye examination; and (3) annual nephropathy screening, recommended in the existing clinical guidelines. We calculated the performance rate of each quality indicator and examined the effects of demographic characteristics and co-morbid conditions. Results We identified 636 diabetes cases. Of these, 97.0% had at least one HbA1c test, and 69.8% had >= 4 tests during the study period. The odds ratios (ORs) for >= 4 HbA1c tests were lower in subgroups aged 75-79 (OR 0.58, 95% confidence interval 0.35-0.96), and aged >= 80 (OR 0.54, 95% confidence interval 0.32-0.88) compared with the subgroup aged < 70 after adjusting for other patient characteristics. The annual rate for eye examinations and nephropathy screenings were 20.8% and 5.8% respectively. Conclusions We found high performance rates for HbA1c testing, while the annual rates for eye examinations and nephropathy screenings were suboptimal. Using administrative data would facilitate more comprehensive assessment of the quality of care in Japan.