2000: Can Uric Acid Protect Joints? Lower Incidence of Large Joint Replacements Among Individuals with Higher SUA

Background/Purpose: Serum uric acid (SUA) has been linked to various health conditions, including osteoarthritis (OA), though findings have been inconsistent. Data on the relationship between SUA and OA in large joints are particularly limited, and its potential association with the need for large joint replacements (LJRs) has not been previously investigated. This study aimed to examine the association between SUA levels and the incidence of LJRs.

Methods: Data were drawn from the GOAL (GOod Ageing in Lahti region) study, a prospective cohort study of individuals aged 52–76 years in Finland’s Lahti region. Baseline data included SUA levels, other laboratory parameters, comorbidities, medication use, lifestyle factors, and socioeconomic variables. Information on LJRs was obtained from the National Care Register for Social Welfare and Health Care. After excluding participants with prior LJRs or cancer diagnoses, 2,403 individuals (1,115 women and 1,288 men) were included. The incidence of large joint arthroplasty over a 12.7-year follow-up was analyzed in relation to SUA levels, adjusting for age, sex, body mass index (BMI), and Charlson Comorbidity Index (CCI). Hyperuricemia was classified as renal when SUA was ≥420 μmol/L (≈7 mg/dL) and estimated glomerular filtration rate (eGFR) ≤67 ml/min/1.73 m² (25^th percentile), and as metabolic when SUA was ≥420 μmol/L with eGFR >67 ml/min/1.73 m².

Results: Over the 12.7-year follow-up period, a total of 303 LJRs were performed in the study population, including 133 hip replacements, 161 knee replacements, 8 shoulder replacements, and 1 elbow replacement; no ankle replacements were reported. In models adjusted for age, sex, BMI, and CCI, higher SUA levels were associated with a lower incidence of LJRs (Figure 1). When analyzing the incidence rate ratio across SUA categories (< 300 µmol/L, 300–359 µmol/L, 360–419 µmol/L, ≥420 µmol/L), a statistically significant decreasing trend in LJRs with increasing SUA was observed (p = 0.006; Table 1). While the adjusted cumulative incidence of first LJR increased with higher SUA, there was no substantial difference between individuals with metabolic versus renal hyperuricemia (Figure 2).

Conclusion: In our study population, individuals with higher SUA levels were less likely to undergo LJR during the 12.7-year follow-up period. This finding has not been previously demonstrated. Future studies are needed to determine whether uric acid has a protective effect on cartilage in large joints, potentially reducing cartilage degradation. Replicating our findings in other studies and further investigating the impact of uric acid on cartilage health are essential.