Background: Low-dose aspirin is commonly prescribed in older adults for cardiovascular prevention, but its potential effect on serum uric acid (SUA) metabolism remains unclear. Experimental studies have suggested that low-dose aspirin may increase the risk of hyperuricemia (HUA), which could influence clinical decision-making. This study aimed to evaluate the association between low-dose aspirin use (50–100 mg/day) and SUA levels, and to explore possible dose–response and subgroup effects among older adults.

Methods: We conducted a cross-sectional analysis of 5,902 participants (median age 69.0 years) aged ≥60 years from the baseline survey of the LAPIS study. Aspirin exposure was categorized as non-use, 50 mg/day, or 100 mg/day. SUA was analyzed as a continuous outcome, and HUA (≥420 μmol/L) as a binary outcome. Multivariable linear and logistic regression models were constructed with progressive covariate adjustment for demographic, clinical, and laboratory variables. A sensitivity analysis excluded diuretic users. Subgroup and interaction analyses were stratified by estimated glomerular filtration rate (eGFR <60 vs ≥60 mL/min/1.73m²), body mass index (BMI <24, 24–27.9, ≥28 kg/m²), and diuretic use.

Results: Aspirin users had higher median SUA levels than non-users (317.0 vs. 304.0 μmol/L, p<0.001). However, in fully adjusted models, aspirin use was not independently associated with SUA or HUA, and no significant dose–response trend was observed. Results remained consistent after excluding diuretic users. Impaired renal function and diuretic use were significantly associated with higher SUA levels. Subgroup analysis identified a significant interaction with BMI (p=0.026), with obese participants (BMI ≥28 kg/m²) showing higher odds of HUA (OR=2.02, 95% CI 1.16–3.61).

Conclusion: In this large sample of older adults, low-dose aspirin (50–100 mg/day) was not independently associated with increased SUA levels or HUA risk. Renal function and diuretic use influenced SUA levels, but aspirin did not exert a differential effect across these groups. The association between aspirin use and HUA was amplified in individuals with obesity. These findings support the metabolic safety of low-dose aspirin in the general elderly population while highlighting the need for SUA monitoring in obese individuals.

Keywords: low-dose aspirin, serum uric acid, hyperuricemia, older adult, obesity interaction

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