Regional variance in patterns of prescriptions for chronic kidney disease in Japan

This study aims to describe the regional variance in prescriptions for chronic kidney disease (CKD) medications and to analyze regional characteristics to identify the sources of these differences by utilizing the National Database of Health Insurance Claims, which provides more than 95% of nationwide claim information for Japan.

Data regarding the total claimed amount for phosphate binders (PBs), erythropoiesis-stimulating agents (ESAs), carbonaceous adsorbents, and potassium-lowering agents in fiscal year 2015 were obtained. Correlation coefficients were calculated for the claimed amount of these drugs per CKD patient and social and medical variables, including the percentage of the population aged ≥ 65 years and the numbers of hospital beds and certified nephrologists. Subsequent multiple regression analysis was performed using explanatory factors affecting the amount of PB or ESA prescriptions per CKD patient.

The total claimed amounts were 585,485,115 for PBs and 2,373,777 for ESAs. Variations in the claimed amount per CKD patient among 47 prefectures were 4.9-, 6.1-, 6.6-, and 6.0-fold for PBs, ESAs, carbonaceous adsorbents and potassium-lowering agents, respectively. The number of nephrologists per CKD patient was positively correlated with the prescribed amount for PBs and ESAs per CKD patient, and independently associated with the prescribed amount also in regression analysis.

Substantial regional variation in CKD-related drug prescriptions exists even within a uniform health care system. The number of certified nephrologists was associated with the prescribed amount for PBs and ESAs. Further studies are needed to clarify whether geographic distribution of certified nephrologist may affect clinical practice pattern.