TY - JOUR

T1 - Ultrasound for the diagnosis of gout-the value of gout lesions as defined by the Outcome Measures in Rheumatology ultrasound group

AU - Christiansen, Sara Nysom

AU - Østergaard, Mikkel

AU - Slot, Ole

AU - Fana, Viktoria

AU - Terslev, Lene

PY - 2021

Y1 - 2021

N2 - OBJECTIVE: To evaluate ultrasound for diagnosing gout using consensus-based Outcome Measures in Rheumatology ultrasound definitions of gout lesions. METHODS: Ultrasound was performed in patients with clinically suspected gout. Joints (28) and tendons (26) were binarily evaluated for the Outcome Measures in Rheumatology gout lesions-double contour (DC), tophus, aggregates and erosions. Ultrasound assessment was compared with two reference standards: (i) presence of MSU crystals in joint/tophus aspirate (primary outcome) and (ii) ACR/EULAR 2015 gout classification criteria (secondary outcome). Both reference standards were evaluated by rheumatologists blinded to ultrasound findings. Sensitivity, specificity, accuracy, positive predictive value and negative predictive value of each ultrasound lesion against both reference standards were determined. RESULTS: Eighty-two patients (70 men), mean age 62.4 (range 19-88) years, were included. Fifty-seven patients were MSU-positive whereas 25 patients were MSU-negative (no MSU crystals: 23; aspiration unsuccessful: 2). Of these 25 patients, three patients were classified as ACR/EULAR-positive (i.e. totally 60 ACR/EULAR-positive patients). All ultrasound lesions had high sensitivities for gout (0.77-0.95). DC and tophus showed high specificities (0.88-0.95), positive predictive values (0.94-0.98) and accuracies (0.82-0.84) when both reference standards were used. In contrast, low specificities were found for aggregates and erosions (0.32-0.59). Ultrasound of MTP joints for DC or tophus, knee joint for DC and peroneus tendons for tophus was sufficient to identify all MSU-positive patients with ultrasound signs of gout at any location. CONCLUSION: Ultrasound-visualized DC and tophus, as defined by the Outcome Measures in Rheumatology ultrasound group, show high specificities, positive predictive values and accuracies for diagnosing gout and are therefore valid tools in clinical practice.

AB - OBJECTIVE: To evaluate ultrasound for diagnosing gout using consensus-based Outcome Measures in Rheumatology ultrasound definitions of gout lesions. METHODS: Ultrasound was performed in patients with clinically suspected gout. Joints (28) and tendons (26) were binarily evaluated for the Outcome Measures in Rheumatology gout lesions-double contour (DC), tophus, aggregates and erosions. Ultrasound assessment was compared with two reference standards: (i) presence of MSU crystals in joint/tophus aspirate (primary outcome) and (ii) ACR/EULAR 2015 gout classification criteria (secondary outcome). Both reference standards were evaluated by rheumatologists blinded to ultrasound findings. Sensitivity, specificity, accuracy, positive predictive value and negative predictive value of each ultrasound lesion against both reference standards were determined. RESULTS: Eighty-two patients (70 men), mean age 62.4 (range 19-88) years, were included. Fifty-seven patients were MSU-positive whereas 25 patients were MSU-negative (no MSU crystals: 23; aspiration unsuccessful: 2). Of these 25 patients, three patients were classified as ACR/EULAR-positive (i.e. totally 60 ACR/EULAR-positive patients). All ultrasound lesions had high sensitivities for gout (0.77-0.95). DC and tophus showed high specificities (0.88-0.95), positive predictive values (0.94-0.98) and accuracies (0.82-0.84) when both reference standards were used. In contrast, low specificities were found for aggregates and erosions (0.32-0.59). Ultrasound of MTP joints for DC or tophus, knee joint for DC and peroneus tendons for tophus was sufficient to identify all MSU-positive patients with ultrasound signs of gout at any location. CONCLUSION: Ultrasound-visualized DC and tophus, as defined by the Outcome Measures in Rheumatology ultrasound group, show high specificities, positive predictive values and accuracies for diagnosing gout and are therefore valid tools in clinical practice.

KW - ACR/EULAR classification criteria

KW - diagnostic accuracy

KW - gout

KW - MSU crystal microscopy

KW - sensitivity and specificity

KW - ultrasound

U2 - 10.1093/rheumatology/keaa366

DO - 10.1093/rheumatology/keaa366

M3 - Journal article

C2 - 32696059

AN - SCOPUS:85099428175

VL - 60

SP - 239

EP - 249

JO - Rheumatology

JF - Rheumatology

SN - 1462-0324

IS - 1

ER -