Prevalence of Urolithiasis by Ultrasonography Among Patients with Gout: A Cross-Sectional Study from the UP-Philippine General Hospital

Context: While urolithiasis is epidemiologically and mechanistically linked to gout, urologic stone disease is not actively investigated in gout patients. Prevalence estimates on the coexistence of urolithiasis in gout have mostly relied on clinical history alone. Purpose: To estimate the prevalence of urolithiasis among adult Filipinos with primary gout through clinical history and ultrasonography. Patients and Methods: Patients diagnosed with primary gout were consecutively enrolled from outpatient clinics of the University of the Philippines Manila-Philippine General Hospital. Clinical data including sex; current age; age at diagnosis, duration of and attack frequency of gout; comorbidities such as hypertension, chronic kidney disease, type 2 diabetes mellitus, and dyslipidemia; personal history of urolithiasis; family history of gout; presence of tophus and laboratory samples to assess general kidney function, serum uric acid level, and urine pH were obtained from each patient who was subsequently subjected to ultrasonographic examination for urolithiasis. Lithiasic and non-lithiasic patients were identified and compared aggregately in terms of the aforementioned features. Results: We recruited 121 patients, 86.8% of whom are male, and 37 (30.6%; 95% CI=23.1-39.3%) were identified to have urolithiasis of which only 12 (9.9%) had history consistent with urolithiasis and 30 (24.8%) were diagnosed solely through ultrasonography. None of the variables of interest were found to be statistically associated (P>0.05) with urologic stone formation. Conclusion: Urolithiasis among adult Filipino patients with primary gout was found to be more prevalent in this study than previous estimates, which were based only on clinical history. We discovered that 25/37 (67.6%) of patients with urolithiasis denied history of urologic stone.