High-frequency HbA1c testing among older patients with diabetes in Japan: a longitudinal analysis using medical claims data.

Abstract

We aimed to determine the rate of high-frequency HbA1c testing among older Japanese patients (≥ 75years) with type 2 diabetes who did not have diabetic complications and were not using insulin, and to explore its influencing factors and association with the number of hospital admissions. A retrospective, longitudinal observation study design based on medical claims data between 2015 and 2020 was adopted. We tracked patients for 3years to describe the annual rate and determine factors associated with high-frequency HbA1c testing using a hierarchical logistical model. We employed a zero-inflated Poisson model to examine the association between frequency of HbA1c testing and the number of hospitalizations. Among 6594 patients included (mean age 80.4years), the rates of high-frequency HbA1c testing in the first, second, and third year were 10.2%, 4.8%, and 4.7%, respectively. Follow-up year [odds ratio (OR) = 0.54, 95% confidence interval (CI) = 0.49-0.59];insulin use (OR = 1.63, 95% CI = 1.26-2.11); multi facility for HbA1c testing (OR = 5.51, 95% CI = 4.66-6.51); more than 48 outpatient days per year (OR = 2.13, 95% CI = 1.81-2.51); hospitalizations (OR = 0.66, 95% CI = 0.55-0.79); two or more classes of antidiabetic agents at baseline (OR = 1.32, 95% CI = 1.11-1.56); and dementia at baseline (OR = 0.70, 95% CI = 0.51-0.97) were significantly associated with high-frequency HbA1c testing. No significant association between frequent HbA1c testing and the number of all-cause hospitalizations was found. We revealed a high rate of HbA1c testing among older Japanese patients with type 2 diabetes in ambulatory care and indicated that high-frequency HbA1c testing was more likely to result from the decentralized healthcare system and its structure.