Serum Urate Monitoring Among Older Adults With Gout: Initiating Urate-Lowering Therapy in Ontario, Canada

Abstract

Objective: To assess the proportion of, and factors associated with, older adults with gout receiving a serum urate (SUA) test after starting urate-lowering therapy (ULT). Methods: We performed a population-based retrospective cohort study in Ontario, Canada in patients ages ≥66 years with gout, newly dispensed ULT between 2010 and 2019. We characterized patients with SUA testing within 6 and 12 months after ULT dispensation. Multilevel logistic regression clustered by ULT prescriber evaluated the factors associated with SUA monitoring within 6 months. Results: We included 44,438 patients with a mean ± SD age of 76.0 ± 7.3 years and 64.4% male. Family physicians prescribed 79.1% of all ULTs. SUA testing was lowest in 2010 (56.4% at 6 months) and rose over time to 71.3% in 2019 (P < 0.0001). Compared with rheumatologists, family physicians (odds ratio [OR] 0.26 [95% confidence interval (95% CI) 0.23–0.29]), internists (OR 0.34 [95% CI 0.29–0.39]), nephrologists (OR 0.37 [95% CI 0.30–0.45]), and other specialties (OR 0.25 [95% CI 0.21–0.29]) were less likely to test SUA, as were male physicians (OR 0.87 [95% CI 0.83–0.91]). Patient factors associated with lower odds of SUA monitoring included rural residence (OR 0.81 [95% CI 0.77–0.86]), lower socioeconomic status (OR 0.91 [95% CI 0.85–0.97]), and patient comorbidities. Chronic kidney disease, hypertension, diabetes mellitus, and coprescription of colchicine/oral corticosteroids (OR 1.31 [95% CI 1.23–1.40]) were correlated with increased SUA testing. Conclusion: SUA testing is suboptimal among older adults with gout initiating ULT but is improving over time. ULT prescriber, patient, and prescription characteristics were correlated with SUA testing.