Understanding International Variations in Kidney Failure Incidence and Initiation of Replacement Therapy.

Introduction: Incidence of kidney replacement therapy (KRT) varies widely across countries. Its relations to individual characteristics, nephrology practices for slowing chronic kidney disease (CKD) progression, and KRT access remain unclear. Methods: We investigated intercountry differences in kidney failure (KF) rate, defined by a sustained estimated glomerular filtration rate (eGFR) <15 ml/min per 1.73 m(2), and separately in KRT incidence, before and after adjusting for risk factors and blood pressure (BP) control or renin-angiotensin-aldosterone system inhibitor (RAASi) prescription practices in the CKD Outcomes and Practice Patterns Study (CKDopps) cohort study. Results: Among 7381 patients with CKD stage 3 to 4 at enrollment, 1297 progressed to KF and 947 initiated KRT over a 3-year follow-up period. Compared to the United States, demographic-adjusted and eGFR-adjusted hazard ratios (HRs) (HRs, 95% confidence intervals [CI]) for a sustained low eGFR were 0.77 (95% CI, 0.57-1.02) in Brazil, 0.90 (95% CI, 0.75-1.08) in France, and 1.03 (95% CI, 0.86-1.03) in Germany. Further adjustment for comorbidities, albuminuria, systolic BP, and RAASi prescription did not substantially change these HRs. In contrast, compared with the United States, the fully-adjusted HR for KRT remained significantly lower in Brazil (0.55, 95% CI 0.39-0.79), higher in Germany (95% CI, 1.36, 1.09-1.69), and similar in France (95% CI, 1.07, 0.81-1.39). Conclusion: Individual risk factors for CKD progression in nephrology patients appeared to explain most intercountry variations in KF but not KRT incidence. This suggests a prominent role for differences in practices related to KRT initiation or access, but not those for slowing disease progression. This study also shows that using KRT as a KF surrogate may bias estimates of associations with CKD progression risk factors.