IgA Nephropathy: Epidemiology, Outcomes, and Insights for Primary Glomerulonephritides

According to the Global Burden of Disease 2019 analysis, there were 606,300 new cases of chronic kidney disease due to glomerulonephritis worldwide, with 17.3 million prevalent cases and 183,700 deaths More interestingly, between 1990 and 2019, the global burden of glomerulonephritis increased by 77% in incidence and 81% in prevalence, mainly due to demographic aging and population growth. Among primary glomerulopathies, IgA Nephropathy (IgAN), also known as Berger's disease, is the most common primary glomerulopathy worldwide, with significant geographic and ethnic variation in incidence, with the highest prevalence in Europe and Asia and the lowest in Africa. Its pathogenesis reflects a complex interaction between polygenic susceptibility and environmental modifiers, mucosal immune activation, infections of the upper respiratory and gastrointestinal tracts, dietary factors, and alterations in the gut microbiome. In addition, IgAN increasingly coexists with other chronic diseases, such as hypertension and diabetes, which complicates both diagnosis and treatment in aging societies. All these observations suggest that in the coming years, the epidemiology of IgAN will gradually transform from a description of "case counts" to a predictive tool that integrates genetic, environmental, and molecular biomarker data. In this sense, epidemiology is increasingly becoming the foundation of precision nephrology-allowing not only for disease risk prediction but also for the design of effective therapeutic strategies. The conceptual shift in IgAN-from a disease defined by biopsy prevalence to one understood through integrative epidemiology-illustrates the broader transition of GN research toward biomarker-based risk stratification and precision medicine. This review focuses on IgA nephropathy as the most prevalent primary glomerulonephritis and uses it as a reference disease to illustrate broader epidemiological patterns, outcome trajectories, and methodological limitations relevant to primary glomerulonephritides.