2025 Volume 58 Issue 11 Pages 490-495
In our previous study, we found that prefectures with a higher rate of dialysis patients diagnosed with unknown primary renal disease tended to report fewer cases of hypertensive nephrosclerosis and diabetic nephropathy. This suggested that hypertensive nephrosclerosis may often be misclassified as unknown in such regions. To further investigate factors contributing to the increase in unknown diagnoses, we analyzed temporal changes in the age‒standardized incidence rate (ASR) of incident dialysis patients. Using data from the Japanese Society for Dialysis Therapy’s WADDA system, we calculated ASRs from 2006 to 2022 and assessed trends across different time periods. ASR for unknown primary disease showed a significant increase from 2014 to 2022 (p ＜0.05), while no significant change was observed from 2006 to 2014. The mean ASR increased from 35.6±1.1 (2006‒2014) to 39.2±1.1 (2017‒2022), a difference of approximately 4.7. This upward trend began in 2015, and may be associated with the 2014 revision of the diabetic nephropathy classification. If appropriately diagnosing stage 4 diabetic nephropathy with normoalbuminuria, ASR for hypertensive nephrosclerosis may increase by about 4.7 per million population. In regions with high rates of unknown primary disease, it is essential to assess the accuracy of diagnosing diabetic nephropathy.
