Gout and allopurinol adherence in newly diagnosed patients and the risk of fractures: a nationwide cohort study

INTRODUCTION / OBJECTIVES: The association between gout and fractures remains controversial due to the competing effects of uric acid's antioxidant properties and gout-induced chronic inflammation. Our study aimed to evaluate the risk of fractures in newly diagnosed gout patients and to analyze the impact of Allopurinol medication adherence on this risk. METHODS: This nationwide cohort study utilized the National Health Insurance Service-National Health Screening Cohort (NHIS-HEALS) database (2002-2019). We identified 4,107 patients newly diagnosed with gout who remained on continuous allopurinol therapy during the 24-month medication assessment period and matched them 1:3 with 12,321 non-gout controls using propensity score matching. Allopurinol adherence was assessed via the Medication Possession Ratio (MPR) over a 24-month period and categorized into three groups: MPR < 0.3, 0.3 ≤ MPR < 0.8, and MPR ≥ 0.8. Multivariable Cox proportional hazards regression was used to calculate adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for fractures (vertebral, hip, and distal radius). RESULTS: Gout patients demonstrated a significantly higher risk of overall fractures compared to the non-gout group (aHR 5.52; 95% CI 4.19-7.26). A significant inverse linear relationship was observed between allopurinol adherence and fracture risk (P for trend < .001). The risk was highest in the low-adherence group (MPR < 0.3; aHR 5.91; 95% CI 4.40-7.93) and relatively lower in the high-adherence group (MPR ≥ 0.8; aHR 4.77; 95% CI 2.94-7.72). Consistent trends were observed for vertebral (aHR 5.68) and hip (aHR 4.22) fractures. These associations remained consistent across all subgroups, including age, sex, and comorbidities. CONCLUSION: Newly diagnosed gout is associated with a substantially increased risk of fractures. Higher adherence to Allopurinol therapy is correlated with a significant reduction in this risk, suggesting that consistent urate-lowering therapy may mitigate gout-related bone fragility. Key Points • Newly diagnosed gout patients have a significantly higher risk of major osteoporotic fractures compared to the non-gout population. • A significant inverse linear relationship exists between Allopurinol adherence and fracture risk, with the highest adherence group (MPR ≥ 0.8) showing a relatively lower risk. • Consistent urate-lowering therapy (ULT) may mitigate bone fragility in gout patients by reducing systemic inflammatory burden caused by urate crystal deposition.