Serum urate levels are a strong predictor of the risk for incident gout, as are ethnicity and hypertension, according to the results of an analysis of data from the Atherosclerosis Risk in Communities (ARIC) study published in Arthritis Research & Therapy.

The investigators identified risk factors that are associated with incident gout, have effects on risk for gout that cannot be completely explained by differences in serum urate concentrations, and may modify the link between gout and serum urate levels. They estimated the unadjusted relationships between gout and certain risk factors using data from the ARIC study by computing odds ratios (ORs) and using chi-square tests. The adjusted associations were then evaluated using logistic regression by sequentially adding 1 risk factor at a time or all risk factors to a baseline model that included serum urate levels only.

Results showed that the average incidence of gout was 2.7 per 1000 individuals per year. Serum urate levels were highly associated with incident gout, with ORs of 3.16 (95% CI, 2.11-4.76) and 25.9 (95% CI, 17.2-38.4) for moderately high (6 to 8 mg/dL) and high (>8 mg/dL) serum urate levels relative to normal serum urate levels (<6 mg/dL). Ethnicity and systolic blood pressure were both additively and independently linked to the presence of gout after serum urate concentrations were taken into account. There were no significant interactions reported between serum urate levels and ethnicity or systolic blood pressure.

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The researchers concluded that with serum urate levels that are near the crystallization threshold (6 to 8 mg/dL), African Americans and individuals with hypertension have a 2- to 3-fold greater risk of developing gout. The risk for gout in this group seems to increase prior to the onset of severe hyperuricemia, defined as serum urate concentrations >7 mg/dL. Additional investigation in larger prospective cohort studies is warranted in order to explore these complex relationships.

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Reference

Sun M, Vazquez AI, Reynolds RJ, et al. Untangling the complex relationships between incident gout risk, serum urate, and its comorbidities. Arthritis Res Ther. 2018;20(1):90.