IgA Nephropathy: Epidemiology and Disease Risk Across the World.

Despite decades of research, our knowledge of the global epidemiology of IgA nephropathy remains limited. Much of what we know about IgA nephropathy incidence comes from biopsy registry studies that are subject to bias related to differences in screening programs, referral patterns, and access to healthcare. Fewer epidemiologic studies used an appropriate data infrastructure that includes a well-defined source population. Nonetheless, all these studies show considerable geographic variation in disease incidence with an increase from west to east and south to north across Eurasia. This pattern is partly explained by the distribution of genetic risk alleles in individuals of European and East Asian ancestry. Although historically thought to be an indolent disease, recent long-term follow-up studies have demonstrated an exceptionally high lifetime risk of kidney failure. The International IgA Nephropathy Prediction Tool, derived and validated in multiple ethnically diverse cohorts, has improved our ability to identify patients at high risk of progression who may benefit from therapies being tested in clinical trials. The earlier identification of high-risk patients, evaluation of novel risk factors, and accurate assessment of global disease burden require high-quality regional data infrastructures and broad collaborative efforts to ensure the impact of new treatments is maximized.