A nationwide prospective cohort study of patients with advanced chronic kidney disease in Japan: The Reach-J CKD cohort study

Epidemiology and outcomes of Japanese patients with advanced chronic kidney disease (CKD)—an estimated glomerular filtration rate (eGFR) < 45 ml/min/1.73 m²—has remained largely unexamined.

We conducted a nationwide survey to determine the distribution of Japanese CKD patients, and are conducting a cohort study of these patients. A questionnaire eliciting details about facilities and their CKD practices was sent to all clinics/hospitals with nephrologists. Based on the survey results, we recruited 2400 advanced CKD patients receiving nephrologist care from at least 30 representative facilities throughout Japan, selected randomly with stratification by region and facility size. Through patient questionnaires and nephrologist-practice surveys aligned with the international CKD Outcomes and Practice Patterns Study (CKDopps), we shall annually or semi-annually collect patient, physician and clinic data prospectively, detailing CKD practices for 5 years, with a primary outcome of death or renal replacement therapy initiation, and secondary outcomes being decline of eGFR by 30% or 50%, CKD progression to CKD G5, or a cardiovascular event.

Of 790 eligible, responding facilities, 330 (41.8%) treat ≥80 advanced CKD patients in the average 3-month period. Regional distribution of these facilities is similar to that of persons in the general population. Hence, the 30 facilities selected for data collection appear to be geographically representative in Japan.

Our study will enhance understanding of various CKD practices and biological data associated with CKD progression, and allow international comparisons using the CKDopps platform. This will provide evidences to improve the health and quality of life for patients with advanced CKD.