Background Tophus burden (TB) was proposed by OMERACT as mandatory domain for chronic gout studies. Image methods although useful, frequently are not available in daily clinical practice.

Objectives To evaluate TB clinically in a cohort of gout patients during 3 years follow-up.

Methods We analyzed baseline and follow-up data (6, 12, 18, 20, 24, 30 and 36 months) of patients with gout (ARA/CGD/ACR-EULAR) from the GRESGO cohort; this analysis includes the patients with ≥1 clinical nodule(s) considered as tophi in the baseline visit. Index tophi size (ITS) was considered as the longer axis of the bigger tophi. TB evaluations: 1) Tophi number (T); 2) ITSt (cm) measured with tape; 3) ITSca (cm), measured with caliper; 4) ITSco, measured with compass. 5) Index tophi hardness (ITh) or consistency, by VAS (0: very soft-10 hard as a rock). This protocol was approved by the local IRB and patients signed and informed consent for their participation.

All the patients received treatment for gout and associated diseases according to published guides and available drugs. The evaluations were done by the same group of physicians (Rheumatologists and Residents). Variables: TB measures, demographic, clinical and biochemical variables. HAQ and EUROQoL and VAS for pain and general health. Inter/intraobserver variability were evaluated. Statistical analysis: t test, X2, r, kappa, Friedman and multiple correlation.

Results 298 patients; 97%males, 203 (68%) tophaceous gout, age, age at onset and duration of the disease were: 46.4±12.7 32.4±12.4 and 14.7±9.3 years respectively. Available ULT: Allopurinol and probenecid, colchicine as prophylaxis. Mean allopurinol dose prescribed at baseline visit was 346.9±154 mg/d and 550±205 mg/d 3 years later.TB values (see table). Index tophi size had r>0.93 among the 3 evaluations (ITSt, ITSca, ITSco) and r<0.3 with ITh. Inter and intraobserver variability was 0.8 and 0.9 respectively; there was significant improvement *(p<0.001) in ITS, sUA, painful, swollen, limited to motion joints, HAQ, EuROQoL, VAS pain, VAS health (patient and physician) also improved significantly.

Conclusions In our cohort, ITSt was the best measure for TB evaluation, the 3 ITS measures had a good correlation between them and less with ITh or consistency. Patients with tophaceous gout, improved significantly with allopurinol and probenecid during 3 years follow-up in TB (ITSt) as well according to the other OMERACT proposed domains for chronic gout.

Disclosure of Interest None declared