U-shaped association between serum uric acid levels with cardiovascular and all-cause mortality in the elderly: The role of malnourishment

Background--The link between elevated serum uric acid (SUA) levels and cardiovascular disease (CVD)-related mortality in the elderly population remains inconclusive. Nutritional status influences both SUA and CVD outcomes. Therefore, we investigated whether SUA-predicted mortality and the effect-modifying roles of malnourishment in older people. Methods and Results--A longitudinal Taiwanese cohort including 127 771 adults 65 years and older participating in the Taipei City Elderly Health Examination Program from 2001 to 2010 were stratified by 1-mg/dL increment of SUA. Low SUA (<4 mg/dL) strata was categorized by malnourishment status defined as Geriatric Nutritional Risk Index < 98, serum albumin < 38 g/L, or body mass index < 22 kg/m². Study outcomes were all-cause and CVD-related mortality. Cox models were used to estimate hazard ratios (HRs) of mortality, after adjusting for 20 demographic and comorbid covariates. Over a median follow-up of 5.8 years, there were 16 439 all-cause and 3877 CVD-related deaths. Compared with the reference SUA strata of 4 to < 5 mg/dL, all-cause mortality was significantly higher at SUA < 4 mg/dL (HR, 1.16; 95% confidence interval, 1.07-1.25) and ≥8 mg/dL (HR, 1.13; confidence interval, 1.06-1.21), with progressively elevated risks at both extremes. Similarly, increasingly higher CVD-related mortality was found at the SUA level < 4 mg/dL (HR, 1.19; confidence interval, 1.00-1.40) and ≥7 mg/dL (HR, 1.17; confidence interval, 1.04-1.32). Remarkably, among the low SUA (< 4 mg/dL) strata, only malnourished participants had greater all-cause and CVD-related mortality. This modifying effect of malnourishment remained consistent across subgroups. Conclusions--SUA ≥ 8 or < 4 mg/dL independently predicts higher all-cause and CVD-related mortality in the elderly, particularly in those with malnourishment.