Chronic Kidney Disease Japan Cohort study: Baseline characteristics and factors associated with causative diseases and renal function

Background: Prevalence of chronic kidney disease (CKD) is estimated to be 13.3 million in Japan, but patient characteristics during the predialysis period (CKD stages 3-5) are not well studied. Methods: We established the Chronic Kidney Disease Japan Cohort (CKD-JAC) to study the incidence of cardiovascular disease (CVD), end-stage renal disease (ESRD), and all-cause mortality in predialysis patients treated by nephrologists for 4 years. The inclusion criteria were (1) Japanese and Asian patients living in Japan, (2) age 20-75 years, and (3) estimated glomerular filtration rate (eGFR) 10-59 ml/min/1.73 m². Results: We analyzed 2977 participants for baseline characteristics. Mean eGFR was 28.6 ± 11.8 ml/min/1.73 m², and mean albuminuria was 976 ± 1340 mg/g Cr. In our study, 91.9% of participants had hypertension, but it was well controlled (131/76 mmHg). Angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) were used by most participants. Less than 15% of participants had history of ischemic heart disease, and 11.5% had history of stroke. Heart failure and arteriosclerosis obliterans were present in 3.9% and 3.6% of patients, respectively. Indicators of arteriosclerosis, higher pulse wave velocity (PWV), and high pulse pressure were associated with diabetes and particularly with diabetic nephropathy. Patients included due to glomerulonephritis seemed to be at low risk for atherosclerosis and also to show lower levels of hypertension. Conclusions: The difference between causative diseases is associated with different comorbidity and level of arteriosclerosis. Future analysis of the cohort will clarify whether incidence of ESRD and CVD differs among causative diseases.