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Women's odds of incident hypertension greater with high uric acid, insulin levels, study reveals

Wednesday, February 18 2009 | Comments

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What's This? Even small differences in uric acid and insulin levels independently predict clinically important, higher odds that incident hypertension will develop in young women, a new study shows.

A research group wrote that several pathophysiologic process mechanisms may explain the etiology of hypertension. Biomarkers associated with these processes have already been linked with hypertension risk, but they may be interrelated. Thus, the investigators sought to determine if the biomarkers of uric acid, insulin, homocysteine, soluble intercellular adhesion molecule-1, and triglyceride levels (to calculate an insulin sensitivity index) were independently associated with hypertension risk.

The nested, case-control analysis was carried out among 1,496 women aged 32 to 52 years who were participating in the prospective, ongoing second Nurses' Health Study. They completed biennial questionnaires about their health and provided blood samples; none had hypertension, diabetes, or coronary disease at baseline. Biomarker measurements in cases who developed incident hypertension were compared with matched controls who did not have hypertension.

The researchers found that all biomarkers individually (without other biomarkers in the model) were associated with hypertension when adjustments were made for standard hypertension risk factors. However, when controlling for all the biomarkers, estimated glomerular filtration rate, and total cholesterol, only uric acid and insulin levels remained independently linked with hypertension.

The odds of hypertension rose by a factor of 1.25 (95% CI, 1.06-1.46) for each 1 mg/dL increase in uric acid. The odds ratio (OR) of hypertension for women whose uric acid level was in the highest quartile (4.6-8.8 mg/dL) versus the lowest quartile (1.5-3.3 mg/dL) was 1.89 (95% CI, 1.26-2.82).

For insulin, the ORs for hypertension were 1.11 (95% CI, 1.03-1.18) for each 2 microIU/mL rise in insulin level and 2.03 (95% CI, 1.35-3.05) for insulin in the highest quartile (7.1-128.8 microIU/mL) rather than the lowest one (0.2-2.8 microIU/mL).

These results were then extrapolated to determine population-attributable risk, or the amount of incident hypertension that could be attributed to high uric acid and insulin levels. The investigators estimated that among women who develop hypertension each year, 30.8% of cases could be attributed to a uric acid level of >=3.4 mg/dL and 24.2% to insulin levels of >=2.9 microIU/mL.

"In conclusion, small differences in uric acid levels and insulin sensitivity, even within ranges considered normal, are robustly and substantially associated with an increased risk of hypertension in young women," the study authors wrote. "Measuring these biomarkers in clinical practice may identify higher-risk individuals." (Forman JP, et al. Arch Intern Med 2009;169:155-162.)

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