Racial differences in gout incidence in a population-based cohort: Atherosclerosis Risk in Communities Study

Abstract

We examined racial differences in gout incidence among black and white participants in a longitudinal, population-based cohort and tested whether racial differences were explained by higher levels of serum urate. The Atherosclerosis Risk in Communities Study is a prospective, US population-based cohort study of middle-aged adults enrolled between 1987 and 1989 with ongoing annual follow-up through 2012. We estimated the adjusted hazard ratios and 95% confidence intervals of incident gout by race among 11,963 men and women using adjusted Cox proportional hazards models. The cohort was 23.6% black. The incidence rate of gout was 8.4 per 10,000 person-years (15.5/10,000 person-years for black men, 12.0/10,000 person-years for black women, 9.4/10,000 person-years for white men, and 5.0/10,000 person-years for white women; P < 0.001). Black participants had an increased risk of incident gout (for women, adjusted hazard ratio (HR) = 1.69, 95% confidence interval (CI): 1.29, 2.22; for men, adjusted HR = 1.92, 95% CI: 1.44, 2.56). Upon further adjustment for uric acid levels, there was modest attenuation of the association of race with incident gout (for women, adjusted HR = 1.62, 95% CI: 1.24, 2.22; for men, adjusted HR = 1.49, 95% CI: 1.11, 2.00) compared with white participants. In this US population-based cohort, black women and black men were at increased risk of developing gout during middle and older ages compared with whites, which appears, particularly in men, to be partly related to higher urate levels in middle-aged blacks.

Keywords: gout; inflammatory arthritis; race; uric acid.

Figure 1.

Flowchart of Atherosclerosis Risk in Communities (ARIC) Study (United States, 1989–2012) participants showing the number of participants excluded for the analysis of race and gout.

Figure 2.

Cumulative incidence of gout between 1987 and 2012 in the US-based Atherosclerosis Risk in Communities Study by race and sex. The cumulative incidence of gout by age was plotted using the Kaplan Meier method according to race and sex strata. The log-rank P value was less than 0.001.

Figure 3.

Distribution of serum urate (in mg/dL) at cohort entry (1987–1989) in the US-based Atherosclerosis Risk in Communities Study by race and sex. The density of serum urate levels at cohort entry (baseline) and normal distribution were plotted by race and sex for A) white women; B) white men; C) black women; and D) black men.