Serum Uric Acid Levels in Older Adults: Associations with Clinical Outcomes and Implications for Reference Intervals in Those Aged 70 Years and Over

OBJECTIVE:Reports have linked both high and low serum uric acid (SUA) levels to adverse health outcomes. This study aimed to establish a reference interval for SUA in older adults and assessed its association with clinically relevant outcomes in relatively healthy, community-dwelling individuals aged ≥70 years old. METHODS:The study used data from the ASPirin in Reducing Events in the Elderly (ASPREE) trial. In Australia, 11,878 ASPREE participants had baseline SUA measurements (median age 74 years old). The study sample (n = 11,446; 55% women) comprised individuals with baseline SUA measurements, excluding those on urate-lowering medication. The reference sample (n = 10,501; 55% women) was established after further exclusion of participants with impaired renal function, defined as an estimated glomerular filtration rate <45 mL/min/1.73m2. Reference intervals (2.5th and 97.5th percentile) were stratified by sex, and Cox proportional hazard models assessed associations between SUA levels and relevant clinical outcomes. RESULTS:SUA reference intervals were 0.24 to 0.54 mmol/L for men and 0.19 to 0.48 mmol/L for women. After adjusting for potential confounders, no association was observed between SUA levels and all-cause mortality, disability-free survival, cardiovascular disease, major adverse cardiovascular events, cancer incidence and mortality, or dementia in either the study or reference samples. In women, however, low SUA levels were associated with an increased risk of fractures (hazard ratio 1.23; 95% confidence interval 1.04-1.46). CONCLUSION:Although previous reports have linked abnormal SUA levels to adverse health outcomes, our findings show no associations within the reference range, except for an increased fracture risk among women with low SUA levels.