Women Have Lower Risk for Gout Than Men at Comparable Uric Acid Levels

Megan Brooks

September 18, 2010

March 30, 2010 — Women with serum uric acid levels higher than 5 mg/dL have a significantly lower risk of developing gout than men with similar uric acid levels, according to 52-year follow-up data from the Framingham Heart Study.

The data also pinpoint obesity, hypertension, alcohol drinking, and diuretic use as key risk factors for gout in women.

Gout has long been viewed a disease that strikes men, and most gout research has focused on men, the study team notes in the April issue of Arthritis & Rheumatism. However, during the past 2 decades, the incidence of gout has roughly doubled among women, particularly in the aging female population.

To help fill the gap in knowledge on gout in women, Dr. Hyon Choi, from the Section of Rheumatology and the Clinical Epidemiology Unit at the Boston University School of Medicine in Massachusetts, and colleagues analyzed the relationship between purported risk factors for gout in 2476 women and 1951 men enrolled in the Framingham study between 1950 and 2002 who were free of gout at baseline.

At baseline, the mean age was 47 years for women and 46 years for men, and mean serum uric acid levels were 4.0 mg/dL and 5.1 mg/dL, respectively. During a 28-year median follow-up period, 104 incident cases of gout in women and 200 in men were identified.

The incidence of gout per 1000 person-years was 1.4 in women compared with 4.0 in men. In both women and men, the incidence of gout increased with increasing serum uric acid level, but the rate of increase was much lower among women, Dr. Choi and colleagues observed.

Gout Incidence Rates at Similar Serum Uric Acid Levels in Women and Men (per 1000 Person-Years)

Serum Uric Acid Levels Women Men
<5.0 mg/dL 0.8 0.8
5.0 - 5.9 mg/dL 2.5 3.4
6.0 - 6.9 mg/dL 4.2 8.0
7.0 - 7.9 mg/dL 13.1 17.8
≥8.0 mg/dL 27.3 32.9

The same pattern was seen in a multivariate model looking at the relative risks for gout among women and men at similar serum acid levels.

Multivariate Risk for Gout in Women and Men

Serum Uric Acid Levels Women RR (95% CI) Men RR (95% CI)
5.0 - 5.9 mg/dL 2.42 (1.46 - 4.02) 4.09 (2.37 - 7.07)
6.0 - 6.9 mg/dL 5.49 (1.76 - 6.63) 9.53 (5.49 - 16.55)
7.0 - 7.9 mg/dL 12.18 (5.87 - 25.27) 22.36 (12.31 - 40.61)
≥8.0 mg/dL 22.53 (9.12 - 55.64) 47.90 (24.02 - 95.53)

Among the purported risk factors for gout in women, increasing age (per 5 years), obesity (body mass index, 30 kg/m2 or higher), alcohol intake (7 ounces or more of pure alcohol/week), hypertension, and diuretic use conferred multivariate relative risks of 1.24, 2.74, 3.10, 1.82, and 2.39, respectively (all P < .05). The magnitude of associations with these factors did not differ significantly from those among men, except for a stronger age effect among women.

Menopause conferred an age-adjusted relative risk of 4.18 (95% CI, 0.55 - 31.86), and the multivariate relative risk was 3.54 (95% CI, 0.46 - 27.15). Among the subgroup of 1249 women who were postmenopausal at baseline, use of hormone replacement therapy was protective (multivariate relative risk, 0.24; 95% CI, 0.03 - 1.79).

These findings, note the authors, "provide the first prospective, quantitative data on the relationship between serum acid levels and the risk of incident gout among women."

The definition of gout, the authors note, was based on a clinical diagnosis of gout by the examining physician and did not require observation of urate crystals in joint fluid. Confirming these results using such specific case definitions, such as urate crystal in joint fluid, "would be valuable," they conclude.

The study was supported in part by a grant from the National Institutes of Health. Full disclosures are available in the article.

Arthritis Rheum. 2010:62;1069-1076.

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