Association between being African-American, serum urate levels and the risk of developing hyperuricemia: Findings from the Coronary Artery Risk Development in Young Adults cohort

Birmingham VA Medical Center 700 South 19th Street, Birmingham, AL 35233, USA.
Arthritis research & therapy (Impact Factor: 3.75). 01/2012; 14(1):R4. DOI: 10.1186/ar3552
Source: PubMed


Findings that African-American race/ethnicity is associated with higher concentrations of serum urate have not been adjusted for possible confounding factors or have not explored this question as a primary outcome. We tested this hypothesis in a bi-racial cohort of younger African-American and white men and women.
Data from 5,049 participants at the Coronary Artery Risk Development in Young Adults (CARDIA) cohort baseline (1985 to 1986) and follow-up for up to 20 years of individuals without hyperuricemia (defined as a serum urate of 6.8 mg/dL or more) at baseline were utilized. We determined associations between race, serum urate and the development of hyperuricemia in sex-specific cross-sectional and longitudinal analyses. Confounding factors examined included: age at enrollment, body mass index, development of hypertension, glomerular filtration rate, medication use, diet and alcohol intake and menopausal symptoms in women.
Referent to whites, African-American men and women had significantly lower concentrations of serum urate at baseline. African-American men had an essentially equal risk of developing incident hyperuricemia during follow-up compared with white men (multivariable adjusted HR = 1.12 (0.88 to 1.40)). African-American women developed a significantly increased risk of hyperuricemia when compared to white women (HR = 2.31 (1.34 to 3.99)).
Young African-American men and women had lower concentrations of serum urate than whites. During longitudinal follow-up, African-American women had a significantly increased risk of developing hyperuricemia when compared with white women, a difference that was not observed in men. Differences in production of serum urate or a more rapid decline in fractional excretion of serum urate are potential, albeit still unproven, explanations for these findings in African-American women.

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    • "Additionally, young African Americans have lower serum urate levels than whites; although African American women are at a higher risk than white women of developing hyperuricemia [12]. Previous studies have identified individual risk factors for increased serum urate levels and incident hyperuricemia in US populations in addition to age, sex, and race: diet, alcohol intake, medication use, and chronic conditions [12,13,15-22]. "
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    ABSTRACT: Increased serum urate levels are associated with poor outcomes including but not limited to gout. It is unclear whether serum urate levels are the sole predictor of incident hyperuricemia or whether demographic and clinical risk factors also predict the development of hyperuricemia. The goal of this study was to identify risk factors for incident hyperuricemia over 9 years in a population-based study, ARIC. ARIC recruited individuals from 4 US communities; 8,342 participants who had urate levels <7.0 mg/dL were included in this analysis. Risk factors (including baseline, 3-year, and change in urate level over 3 years) for 9-year incident hyperuricemia (urate level of >7.0 g/dL) were identified using an AIC-based selection approach in a modified Poisson regression model. The 9-year cumulative incidence of hyperuricemia was 4%; men = 5%; women = 3%; African Americans = 6% and; whites = 3%. The adjusted model included 9 predictors for incident hyperuricemia over 9 years: male sex (RR = 1.73 95% CI:1.36-2.21), African-American race (RR = 1.79 95%CI:1.37-2.33), smoking (RR = 1.27, 95%CI: 0.97-1.67), <HS education (RR = 1.27, 95%CI:0.99-1.63), hypertension (RR = 1.65, 95%CI:1.30-2.09), CHD (RR = 1.57, 95%CI:0.99-2.50), obesity (class I RR = 2.37, 95%CI:1.65-3.41 and >= class II RR = 3.47, 95%CI:2.33-5.18), eGFR < 60 (RR = 2.85, 95%CI:1.62-5.01) and triglycerides (Quartile 4 vs. Quartile 1: RR = 2.00, 95%CI:1.38-2.89). In separate models, urate levels at baseline (RR 1 mg/dL increase = 2.33, 95%CI:1.94-2.80) and 3 years after baseline (RR for a 1 mg/dL increase = 1.92, 95%CI:1.78-2.07) were associated with incident hyperuricemia after accounting for demographic and clinical risk factors. Demographic and clinical risk factors that are routinely collected as part of regular medical care are jointly associated with the development of hyperuricemia.
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    ABSTRACT: The aim of the present study was to determine whether serum urate (sUA) concentration is positively associated with subclinical atherosclerosis, independent of body mass index (BMI), among generally healthy adults. The CARDIA study followed 5115 black and white individuals aged 18-30 years in 1985-1986 (year 0). Subclinical atherosclerosis comprised coronary artery calcified plaque (CAC; years 15, 20 and 25) and maximum common carotid intima-media thickness (IMT; year 20). sUA (years 0, 10, 15 and 20) was modelled as gender-specific quartiles that were pooled. Discrete-time hazard regressions and generalized linear regressions were used for analyses. Mean sUA concentration was lower in women than in men, and increased with age. Adjusting for demographic and lifestyle factors, the highest versus lowest quartile of sUA at year 0 was associated with a 44% [95% confidence interval (CI) 20%, 73%] greater risk of CAC progression from year 15 to 25 (Ptrend < 0.001), which was attenuated by adjustment for BMI at year 0 (Ptrend = 0.45). A stronger association was found between sUA at year 15 and CAC progression at year 20 or 25 (hazard ratio 2.07, 95% CI 1.66, 2.58 for the highest versus lowest sUA quartile Ptrend < 0.001), which was attenuated but remained significant with additional adjustment for BMI at year 15 (Ptrend = 0.01). A greater increment in sUA concentration from year 0 to year 15, independent of change in BMI, was related to a higher risk of CAC progression (Ptrend < 0.001). Similar associations were found between sUA and IMT, but only in men. sUA may be an early biomarker for subclinical atherosclerosis in young adults; starting in early middle age, sUA predicts subclinical atherosclerosis independently of BMI. This article is protected by copyright. All rights reserved.
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