The French Chronic Kidney Disease-Renal Epidemiology and Information Network (CKD-REIN) cohort study.

BACKGROUND: While much has been learned about the epidemiology and treatment of end-stage renal disease (ESRD) in the last 30 years, chronic kidney disease (CKD) before the end-stage has been less investigated. Not enough is known about factors associated with CKD progression and complications, as well as its transition to ESRD. We designed the CKD-renal epidemiology and information network (REIN) cohort to provide a research platform to address these key questions and to assess clinical practices and costs in patients with moderate or advanced CKD. METHODS: A total of 46 clinic sites and 4 renal care networks participate in the cohort. A stratified selection of clinic sites yields a sample that represents a diversity of settings, e.g. geographic region, and public versus for-profit and non-for-profit private clinics. In each site, 60-90 patients with CKD are enrolled at a routine clinic visit during a 12-month enrolment phase: 3600 total, including 1800 with Stage 3 and 1800 with Stage 4 CKD. Follow-up will continue for 5 years, including after initiation of renal replacement therapy. Data will be collected from medical records at inclusion and at yearly intervals, as well as from self-administered patient questionnaires and provider-level questionnaires. Patients will also be interviewed at baseline, and at 1, 3 and 5 years. Healthcare costs will also be determined. Blood and urine samples will be collected and stored for future studies on all patients at enrolment and at study end, and at 1 and 3 years in a subsample of 1200. CONCLUSIONS: The CKD-REIN cohort will serve to improve our understanding of the biological, clinical and healthcare system determinants associated with CKD progression and adverse outcomes as well as of international variations in collaboration with the CKD Outcome and Practice Pattern Study (CKDopps). It will foster CKD epidemiology and outcomes research and provide evidence to improve the health and quality of life of patients with CKD and the performances of the healthcare system in this field.