Kidney and Cardiovascular Outcomes by Chronic Kidney Disease Stage and Etiology of Chronic Kidney Disease: A Randomly Selected Nationwide Prospective Multicenter Cohort Study in Japan (Reach-J Study).

INTRODUCTION

Kidney disease is a global health priority. Accurate identification of primary diseases causing end-stage kidney disease is essential.

METHODS

We established the REACH-J cohort, a nationwide prospective cohort of patients with advanced chronic kidney disease (CKD) under nephrologist care, using random sampling across 31 institutions. Patients with CKD stages G3b-G5 completed lifestyle and medical surveys; institutions provided medical history data over 5 years of follow-up.

RESULTS

Among 2,249 patients (mean age, 69.1 ± 12.6 years), primary CKD etiologies were diabetic kidney disease (DKD; 24.5%), nephrosclerosis (NSc; 24.4%), polycystic kidney disease (PKD; 5.8%), and others (45.3%). Event rates (per 100 person-years) were 3.0 for all-cause mortality, 2.0 for pre-kidney replacement therapy (KRT) death, and 8.4 for KRT initiation. Among patients at stage G3b at enrollment, the primary disease most frequently associated with KRT initiation was diabetes. However, among patients at stage G4 or G5 at enrollment, the condition most frequently associated with KRT initiation was PKD. NSc had the lowest KRT initiation rate. Mortality was highest in stage G3b DKD, followed by NSc. Kaplan-Meier analysis showed early KRT initiation in DKD, later surpassed by PKD. Across etiologies, higher proteinuria predicted poorer renal outcomes, whereas cardiovascular and mortality rates did not differ by proteinuria stage.

CONCLUSIONS

Although DKD is the leading cause of end-stage kidney disease worldwide, PKD most commonly leads to dialysis in patients with CKD stages 4-5 under the nephrologist's control. In contrast, non-proteinuric NSc conferred a very low risk of end-stage kidney disease, even in advanced CKD (G3b-G5).