The incidence and prevalence of immunoglobulin A nephropathy in the United States.

Aims: Reliable national estimates for the incidence and prevalence of immunoglobulin A nephropathy (IgAN) in the United States (U.S.) are needed. We performed a national survey with pathologists and used insurance claims data to estimate IgAN frequency nationwide.

Materials and methods: An online survey with pathologists was conducted between November and December 2021 to obtain data on the number and types of biopsies evaluated and the proportion with IgAN confirmed. Biopsy data were extrapolated to two different claims databases to estimate incidence and prevalence. Results were validated against a separate dataset of electronic health records.

Results: A total of 43 pathologists from across U.S. regions reported evaluating a mean of 169 kidney biopsies (standard deviation 179.1) in the past 12 months. Of the 7,267 total biopsies evaluated, 632 (8.7%) were IgAN. Based on the respective claims databases, annual incidence rates of 2.1 and 2.2 per 100,000 and prevalence rates of 59.9 and 62.7 per 100,000 were estimated. Results from the validation dataset were similar, with an incidence of 1.9 per 100,000 and prevalence of 54.2 per 100,000.

Conclusion: This study estimated incidence and prevalence of IgAN. Extrapolating the findings to the U.S. population for 2021, total prevalence was 198,887 - 208,184 persons.