Is serum uric acid level associated with all-cause mortality in high-functioning older persons: MacArthur studies of successful aging?

OBJECTIVES

To explore the effect of serum uric acid level on subsequent all-cause mortality in high-functioning community-dwelling older persons. It is controversial whether high serum uric acid level is a true independent risk factor for cardiovascular and total mortality or the association is due to other confounding variables. Furthermore, it remains unclear whether the predictive value of uric acid level on mortality observed in younger cohorts can be extended to older people.

DESIGN

Prospective cohort study.

SETTING

A sample of community-dwelling older people.

PARTICIPANTS

A cohort of 870 participants from the MacArthur Studies of Successful Aging.

MEASUREMENTS

Baseline information was obtained for serum uric acid level, C-reactive protein (CRP), interleukin-6 (IL-6), prevalent medical conditions, and health behaviors. Crude and multivariate logistic regression analyses were used to examine the association between serum uric acid levels and 7-year all-cause mortality, while adjusting for potential confounders.

RESULTS

In men, the multiply adjusted risk ratios for 7-year total mortality were 1.07 (95% CI=0.61-1.88) for the mid tertile of uric acid level and 1.24 (95% CI=0.70-2.20) for the top tertile. In women, the multiply adjusted risk ratios were 0.58 (95% CI=0.29-1.18) and 0.47 (95% CI=0.22-0.99), for the mid and top tertiles respectively. CRP and IL-6 were important confounders in the relationship between serum uric acid and overall mortality.

CONCLUSIONS

High serum uric acid level is not independently associated with increased total mortality in high-functioning older men and women. When evaluating the association between serum uric acid and mortality, the potential confounding effect of underlying inflammation and other risk factors must be considered.