Background The prevalence of urolithiasis in general Chinese population was 5%>10%. It has been reported as a common complication of gout in many countries (20%>39.5%) but not yet in China. Urolithiasis is one of the contraindications of uricosuric drugs. However, allopurinol, the only other available urate lowering drug in China, has been confirmed high risk of allopurinol hypersensitivity syndrome in Chinese population and those with chronic kidney disease.
Objectives To investigate the prevalence of urolithiasis in southern Chinese gout patients and the possible risk factors.
Methods 201 hospitalized patients with primary gout were recruited and their clinical data were collected. Current urolithiasis was defined as positive image finding including ultrasound, plain film or computer tomography. Positive history of urolithiasis delivery or urolithiasis surgery but negative image finding was defined as previous urolithiasis.
Results (1)Among 201 gout patients, 89.1% were male with mean age 57.5±16.9 years while 10.9% were female with mean age 68.5±11.9 years. The mean disease duration was 7.9±7.4 years with involved joints 6.4±7.4. 30.7% patients presented tophi. The average serum uric acid (sUA) was 8.9±2.7mg/dl with 24h uric acid excretion 451.9±240mg. 91.6% patients excreted uric acid lower than 800mg/24h. Serum creatinine was 133.1±84.6umol/l and estimate glomerular filtration rate (eGFR) 60.0±19.4ml/min. (2) 33.8% patients complicated with urolithiasis, of which 75.0% were current urolithiasis and 33.8% were current urolithiasis without positive urolithiasis history. 84.3% were neprolithiasis and 57.1% were multiple urolithiasis. (3)Table 1 showed significant differences of sUA, hyperuricemia, eGFR, impaired renal function and renal cyst between urolithiasis group and non-urolithaisis group. Current urolithiasis exacerbate eGFR more than previous urolithiasis (51.4±18.3ml/min VS 61.8±17.8ml/min, P=0.045). (4) Urolithiasis was significantly correlated with hyperuricemia (r=0.156, P=0.027), impaired renal function (r=0.27, P<0.001) and renal cyst (r=-0.252, P<0.001). Logistic regression showed that renal cyst negatively predicted the presence of urolithiasis in gout patients (OR=0.066, 95%CI 0.013-0.298, P=0.001) while eGFR<60ml/min promoted urolithiasis (OR=3.786, 95%CI 1.516-9.454, P=0.004).
Conclusions Our results showed high prevalence of urolithiasis in southern Chinese gout patients. Routine imaging test on urinary system should be performed to detected urolithiasis in all gout patients especially for those with renal impairment.
Disclosure of Interest None Declared