Global Incidence of IgA Nephropathy by Race and Ethnicity: A Systematic Review

Background The reported incidence of IgA nephropathy (IgAN) varies widely across studies and may vary based on race/ethnicity. This study systematically reviewed the incidence of IgAN in the United States (US) and other countries and explored variability based on the racial/ethnic composition and other demographic characteristics of different populations. Methods This was a systematic review. Studies were eligible for inclusion if they contained data collected from January 1, 1974 to December 31, 2021 and reported IgAN incidence at a population level (i.e., cases of IgAN per 100,000 population). Results Five US and sixteen international studies were included; three of the US studies reported the race-specific incidence of IgAN. In the US, the reported incidence of IgAN ranged from 0.39 per 100,000 in Tennessee to 1.4 per 100,000 in Minnesota; internationally, IgAN ranged from 0.06 per 100,000 in South Africa to 4.2 per 100,000 in Japan. Findings regarding the incidence of IgAN in the US by race were inconsistent: one study found a higher incidence among Whites compared to Blacks, one study found a lower incidence in Whites, and one study found no difference. Globally, the incidence of IgAN appeared to be higher in Asian than in non-Asian populations and higher in males than in females. Conclusions Reported incidence of IgAN varies widely; there is no consensus regarding the relationship between race and IgAN. Incidence rates appeared to be higher in Asians than non-Asians, and in males than females. We recommend that future studies should report IgAN incidence rates by race/ethnicity and account for the demographic characteristics of the background population.