THU0445 PREVALENCE AND INFLUENCE OF DISEASE DURATION IN THE AMOUNT OF ARTICULAR AND PERIARTICULAR DEPOSITS OF MONOSODIUM URATE (MSU) CRYSTALS IN NON-TREATED GOUTY ARTHRITIS PATIENTS

Abstract

Background:Monosodium urate crystals deposition arthritis (Gout) is the most prevalent inflammatory arthropathy in our society. The use of muskuloskeletal ultrasound (MSUS) is emerging as a diagnostic method of patients with gout, mainly in the past few years.Objectives:Our objective is to establish the prevalence of articular and periarticular ultrasound lesions in patients with known or recent gout diagnosis without urate-lowering therapy (ULT) as well as to analyze the influence of disease duration on these findings.Methods:Observational, cross-sectional and descriptive study, including patients with diagnosis of Gout (fulfilling the ACR / EULAR Classification Criteria 2015) between September and November 2019 in our Rheumatology service of a tertiary center. Demographic and clinical records were collected (table 1) and MSUS was performed on each patient systematically by two rheumatologists, exploring a total of 20 structures (8 tendons and 12 joints). Suggestive images of MSU crystals deposition were defined following the OMERACT 2015 ultrasound elementary lesions definitions. Deposits included lesions as tophus, hyperechoic aggregates (HA) and double contour (DC).Table 1.Demographic and laboratory dataFeaturesPatients (n=38)%SexMen 34 Women 489,5 10,5Age (years)Mean ±SD 60±14,43ComorbiditiesArterial hypertension18 Mellitus diabetes 4 Dyslipidemia 13 Smoking 7 Alcohol 1447,4 10,5 34,2 18,4 36,8BMI (Kg/m2)Mean±SD 27,3±4,23Blood urate levels (mg/dL)Mean±SD 8,2±1,74Blood creatinine levels (mg/dL)Mean±SD 1,09±0,75Results:A total of 38 patients were included, 34 men (89.5%) and 4 women (10.5). Twenty seven (71.1%) presented MSU crystals in synovial fluid samples, while rest of them (28.9%) met 2015 ACR / EULAR Clasiffication Criteria for Gout. Disease duration (since onset of symptoms) was less than 6 months in 20 patients (52.6%) and longer than 6 months in 18 (47.36%). Thirty seven patients (97.36%) presented some type of MSU deposits on the explored areas. One hundred and thirty (17,10%), out of 760 explored locations, had MSU deposits. Patients with disease duration less than 6 months had 56 locations with deposits (43.07%), while those with a symptomathology longer than 6 months had 74 locations with deposits (56.92%). Left knee was the most frequent location of UMS deposits (78.95%). Out of the 145 MSUS images with elementary lesions due to MSU crystal deposits, 28 were tophi (19.31%), 33 HA (22.75) and 84 DC (57.93%). Out of the total images with deposits (DC, HA and tophi), DC in the left knee was the most frequent (21.38%), followed by DC in right knee (17.24%) and DC in 1st MTP (10.24%).Conclusion:Almost 100% of patients with recently diagnosed gout without ULT, presented on at least one of the scanned locations MSUS images suggestive by MSU crystals deposition. Most of MSU crystals deposits were on knees and 1st MTP. Patients with non-treated longer than 6 months of disease duration gout had a greater number of MSU crystals deposit locations detected by MSUS. The presence of tophi and HA was statistically higher in patients with disease duration longer than 6 months (table 2).Table 2.MSU crystals median locations and MSUS images in both groups<6months (n,%)>6months (n,%)p valueDeposits locations56 (43,07)74 (56,92)0,0751MSUS images with deposits -Tophi Median, IR () - HA Median, IR () - DC Median, IR ()8 (28,57) 0 (0-0) 7 (21,21) 0 (0-0) 39 (46,43) 0,5 (0-1)20 (71,43) 0 (0-1) 26 (78,79) 0 (0-1) 45 (53,57) 0 (0-2)0,01810,02310,85311Mann-Whitney U test comparing medians between both groups IR: interquartile range