Explaining the racial difference in AKI incidence.

African Americans face higher risk of AKI than Caucasians. The extent to which this increased risk is because of differences in clinical, socioeconomic, or genetic risk factors is unknown. We evaluated 10,588 African-American and Caucasian participants in the Atherosclerosis Risk in Communities study, a community-based prospective cohort of middle-aged individuals. Participants were followed from baseline study visit (1996-1999) to first hospitalization for AKI (defined by billing code), ESRD, death, or December 31, 2010. African-American participants were slightly younger (61.7 versus 63.1 years, P<0.001), were more often women (64.5% versus 53.2%, P<0.001), and had higher baseline eGFR compared with Caucasians. Annual family income, education level, and prevalence of health insurance were lower among African Americans than Caucasians. The unadjusted incidence of hospitalized AKI was 7.4 cases per 1000 person-years among African Americans and 5.8 cases per 1000 person-years among Caucasians (P=0.002). The elevated risk of AKI among African Americans persisted after adjustment for demographics, cardiovascular risk factors, kidney markers, and time-varying number of hospitalizations (adjusted hazard ratio, 1.20; 95% confidence interval [95% CI], 1.01 to 1.43; P=0.04); however, accounting for differences in income and/or insurance by race attenuated the association (P>0.05). High-risk APOL1 variants did not associate with AKI among African Americans (demographic-adjusted hazard ratio, 1.07; 95% CI, 0.69 to 1.65; P=0.77). In summary, the higher risk of AKI among African Americans may be related to disparities in socioeconomic status.