THE RELATIONSHIP BETWEEN CLINICAL SYMPTOMS AND ULTRASONOGRAPHIC SIGNS IN GOUT

Abstract

For the first time, the new ACR/EULAR gout classification criteria incorporate ultrasound (US) evidence of double contour sign (DC), an articular cartilage abnormality related to the deposition of crystals on the surface of the hyaline cartilage, as a sign specific to gout. US recently has been used as an objective diagnostic tool for detecting urate deposition (tophus (T), DC) or joint damage (erosion) in gout. Objective: Our aim was to investigate the relationship between clinical gout activity and load of US changes, also to examine the concordance between patient reported joint attack (PRGA) and ultrasonographic intraarticular changes. Methods: Sixty monosodium-urate-crystal-confirmed gout patients and 36 healthy controls were prospectively included in one centre. The relationship between clinical symptoms and ultrasonographic gout-related changes investigating 36 joints and 4 tendons (m. triceps and patellar) was evaluated using Spearman’s correlation and agreement analysis (kappa coefficient). Results: moderate, positive correlation was observed between the number of subcutaneous tophi and total US tophus area (rs=0,628), total number of DC (rs=0,612), and erosions (rs=0,526), all p<0, 0001, found per patient on US. Gout attacks and disease duration significantly positively correlated with the load of all investigated US changes (p<0, 01). Investigating 1980 joints in 55 gout patients irrespective of treatment and disease duration, symptoms were reported in 307 (15,5%) joints while ultrasound detected signs of urate deposition and erosions in 416 (20,9%) and 143 (7,2%) joints, respectively. The overall concordance rate with PRGA in the joint was fair for tophus (κ= 0,333), especially in the wrist and ankle, also fair for DC (κ= 0,275) and erosion (κ= 0,217). There was large number of clinically false negative joints with T and/or DC found on US, but also negative intraarticular US in patient-reported arthritis. Better concordance, considered as moderate between PRGA and any sign of urate deposition (US T or DC) was found, investigating 1008 joints in untreated (28) gout subgroup (κ= 0,498) compared to treated (κ= 0,231). The specificity of US T, DC, and erosion was 81% (p<0, 0001), 86% (p<0, 0001), and 70% (p<0, 01), respectively. Conclusions: Ultrasonographic changes positively correlate with disease activity and duration in gout with fair to moderate concordance between patientreported gout attack and intraarticular US findings. Not only symptomatic joints should be used for US gout classification in clinical practice.