SAT0614 Ultrasound and urate crystal deposition: how many joints to screen?

Background

Gout is one of the most common inflammatory joint disease in males. The new ACR/EULAR 2015 gout classification criteria has included imaging as a scoring item [1]. Naredo et al [2], found that in intercritical gout, assessment of one joint (ie, radiocarpal) and two tendons (ie, patellar and triceps) for HAGs, and three articular cartilages (ie, first metatarsal, talar and second metacarpal/femoral) for double contour sign (DCS) showed the best balance between sensitivity and specificity (84.6% and 83.3%, respectively). Ultrasound screening at these 6 sites is time consuming and not feasible in a busy outpatient service. So we aimed to compare the two sites (knee and 1st MTP joints) with these 6 sites for the ultrasound detected abnormalities namely DCS and HAGs in patients of gout particularly with the idea to find the best possible minimum joint combination without compromising the sensitivity and specificity.

Objectives

To compare the ultrasound-detected abnormalities namely double contour sign (DCS) and hyperechoic aggregates (HAGs) at knee and first metatarsophalangeal (1st MTP) joint (two sites) verses six sites (knee joint, 1st MTP joint, radiolcarpal joint, patellar tendon and triceps tendon) in patients of gout.

Methods

Forty seven gout and fifty controls (serum uric acid <7mg/dl) with age more than 18 years were included in this study. DCS was looked for at three articular cartilage sites (first metatarsal, tibiotalar and femoral condyle) whereas HAGs were looked for at one joint site (radiocarpal joint) and two tendon sites (patellar tendon and triceps tendon). Ultrasound findings of all three groups were compared.

Results

We found sensitivity, specificity, positive predictive value, negative predictive value and positive likelihood ratio of two joint areas (knee and 1st MTP) ultrasound findings for gout were 87.2%, 84%, 83.7%, 85.6% and 5.5 respectively. Similar sensitivity, specificity, positive predictive value, negative predictive value and positive likelihood ratio were observed with 6 sites ultrasound findings. Amongst controls 17.5% were found to have these abnormal ultrasound findings by both two joint area and 6 sites exams.

Conclusions

Screening of two joint areas (knee and 1st MTP) has similar sensitivity, specificity and positive likelihood ratio as compared to six sites in diagnosing gout. While utilizing lesser time in examination.

References

Neogi T, Tim L, Dalbeth N, Fransen J, Schumacher HR, Berendsen D, et al. 2015 Gout classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Annals of the Rheumatic Diseases. 2015;74:1789. Naredo E, Uson J, Jiménez-Palop M, Martínez A, Vicente E, Brito E, et al. Ultrasound-detected musculoskeletal urate crystal deposition: which joints and what findings should be assessed for diagnosing gout? Ann Rheum Dis 2014;73: 1522–1528.

Disclosure of Interest

None declared