Objective:To explore the clinical characteristic and risk factors of subcutaneous tophus among hospitalized gout patients.Methods:The clinical data of 646 inpatients with gout from April 2014 to December 2019 in Tianjin Medical University Chu Hsien-I Memorial Hospital were retrospectively analyzed. The patients were divided into tophus group (172 cases) and non-tophus group (474 cases) according to the presence of subcutaneous tophus. The body height, body mass, waist circumference, hip circumference and blood pressure were measured. The total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), urea nitrogen, creatinine, uric acid and C-reactive protein (CRP) were detected; urine was collected for 24 h to detect uric acid. The body mass index (BMI), estimated glomerular filtration rate (eGFR) and uric acid excretion fraction (FUA) were counted. Binary Logistic regression analysis was used to analyze the independent risk factors of subcutaneous tophus among hospitalized gout patients.Results:The proportion of male, course of disease, number of joint involved in attack, rate of smoking history, rate of drinking history, smoking amount, alcohol consumption volume, length of time spent drinking, length of time spent smoking, LDL-C, urea nitrogen, serum creatinine and serum uric acid in tophus group were significantly higher than those in non-tophus group: 98.84% (170/172) vs. 94.09% (446/474), 10 (5, 16) years vs. 5 (2, 9) years, 6 (4, 8) joints vs. 3 (2, 5) joints, 66.86% (115/172) vs. 58.44% (277/474), 65.70% (113/172) vs. 57.38% (272/474), 11 (0, 20) cigarettes /d vs. 10 (0, 20) cigarettes/d, 100 (0, 250) ml/d vs. 50 (0, 162) ml/d, 10 (0, 26) years vs. 0 (0, 20) years, 20 (0, 30) years vs. 10 (0, 20) years, (3.44 ± 0.98) mmol/L vs. (3.25 ± 0.97) mmol/L, 5.81 (4.61, 7.46) mmol/L vs. 5.38 (4.39, 6.66) mmol/L, 89.4 (74.3, 107.5) μmol/L vs. 85.1 (72.5, 98.9) μmol/L and 514.4 (452.9, 595.2) μmol/L vs. 499.0 (404.8, 572.4), the onset age, red blood cell, hemoglobin and eGFR were significantly lower than those in non-tophus group: (37.78 ± 10.56) years old vs. (40.17 ± 13.06) years old, (4.72 ± 0.74) × 10 9/L vs. (4.88 ± 0.56) × 10 9/L, (141.15 ± 17.19) g/L vs. (146.00 ± 13.06) g/L and 87.7 (65.9, 108.4) ml/min vs. 93.3 (75.9, 113.1) ml/min, and there were statistical differences ( P<0.05 or <0.01); there were no statistical differences in family history of diabetes, family history of hypertension, family history of gout, BMI, waist-hip ratio, blood pressure, FUA, white blood cell, TC, TG, HDL-C and CRP between 2 groups ( P>0.05). The patients were grouped according to the course of disease, the incidences of tophus in patients with course of disease ≤5.0 years, 5.1 to 10.0 years and >10.0 years were 15.34% (50/326), 27.67% (44/159) and 48.45% (78/161), and there was statistical difference ( χ2 = 60.59, P<0.01); the patients were grouped according to the quartiles of serum uric acid, the incidences of tophus in patients with serum uric acid <424.05 μmol/L, 424.05 to 505.24 μmol/L, 505.25 to 576.17 μmol/L and ≥576.18 μmol/L were 14.91% (24/161), 32.72% (53/162), 29.01% (47/162) and 29.81% (48/161), and there was statistical difference ( χ2 = 15.70, P<0.01). Binary Logistic regression analysis result showed that the course of gout, smoking amount, number of joint involved in attack, serum uric acid and LDL-C were the independent risk factors of subcutaneous tophus among hospitalized gout patients ( OR = 1.069, 1.020, 1.317, 1.002 and 1.262; 95% CI 1.032 to 1.097, 1.006 to 1.032, 1.223 to 1.417, 1.000 to 1.003 and 1.033 to 1.541; P<0.01 or <0.05). Conclusions:The duration of disease, number of involved joint, serum uric acid level, unhealthy lifestyles and lipid metabolism disorders are the independent risk factors of subcutaneous tophus among hospitalized gout patients.