Two- vs six-site ultrasound screening yields similar sensitivity in diagnosing gout
Ultrasonographic screening of two sites is as accurate as screening six sites in diagnosing gout, as shown in a recent study.
Researchers examined 47 gout patients and 50 controls (serum uric acid <7 mg/dL) to evaluate ultrasound-detected abnormalities—double contour sign (DCS) and hyperechoic aggregates (HAGs)—at two sites (knee and first metatarsophalangeal [1st MTP] joints) vs six sites (knee joint, 1st MTP joint, radiocarpal joint, talar joint, patellar tendon, and triceps tendon).
Three articular cartilage sites (first metatarsal, tibiotalar, and femoral condyle) were examined for DCS, whereas a single joint site (radiocarpal joint) and two tendon sites (patellar tendon and triceps tendon) were examined for HAGs. Ultrasound findings from both groups were compared.
Examination of two sites was able to detect gout with a sensitivity of 87.2 percent, specificity of 84 percent, positive predictive value (PPV) of 83.7 percent, negative predictive value (NPV) of 85.6 percent, and positive likelihood ratio (LR) of 5.5. Six-site ultrasound findings had similar sensitivity, specificity, PPV, NPV, and positive LR.
Moreover, in the control group, 16 percent showed abnormal ultrasound findings via both two-site and six-site examinations.
Ultrasound has been reported as an important, noninvasive means to diagnose gout. In patients with typical clinical signs and the DCS, hypoechoic to hyperechoic, inhomogeneous material surrounded by a small anechoic rim, representing tophaceous material and erosions adjacent to tophaceous material on ultrasound, it may be possible to make a diagnosis of gouty arthritis and initiate treatment without performing a needle aspiration of the acutely inflamed joint or suspected tophus. [Rheumatology 2007;46:1116–1121]