Clinical characteristics associated with subcutaneous tophi formation in Chinese gout patients: a retrospective study

The objective of this study is to analyze clinical characteristics associated with the formation of subcutaneous tophi among Chinese gout patients. It was a retrospective outpatient cohort study. Five thousand six hundred ninety-three gout patients treated at the Affiliated Hospital of Qingdao University from March 2011 to February 2016 were included and divided into the tophus group and non-tophus group according to the presence of megascopic tophus. Relevant clinical information and biochemical parameters were analyzed to identify potential risk factors for the incidence of subcutaneous tophi. There are significant difference (P < 0.05) between the tophus and non-tophus groups in gender, family history, exercise, incidence of obesity, hypertension, renal dysfunction, kidney stone, coronary heart disease, and upper limb joint involvement. Between the two groups, significant difference (P < 0.01) was detected in the onset age (43.80 ± 13.82 years vs. 45.40 ± 13.77 years), duration of disease (10.28 ± 7.54 years vs. 5.11 ± 6.06 years), number of joint involved (3.11 ± 2.15 vs. 1.81 ± 1.35), systolic pressure (138.53 ± 19.46 mmHg vs. 133.87 ± 17.93 mmHg), diastolic pressure (89.55 ± 12.73 mmHg vs. 87.48 ± 11.77 mmHg), serum uric acid (487.15 ± 120.13 μmol/L vs. 458.89 ± 119.04 μmol/L), creatinine (93.87 ± 54.19 μmol/L vs. 85.51 ± 37.71 μmol/L), and creatinine clearance rate (Ccr) (93.05 ± 48.7 mL/min vs. 106.61 ± 51.76 mL/min). Logistic regression analysis suggests that duration of disease, number of joints involved, involvement of upper limb joints, kidney stones, diastolic pressure, and serum uric acid are associated with the subcutaneous tophi formation, while exercise and obesity are protective factors. The present study has identified several clinical parameters (such as duration of disease, involvement of upper limb joints, involved joints, kidney stone, hypertension) as risk factors for the incidence of subcutaneous tophi, which provides insights into the treatment and prevention of tophus.