To compare ultrasound-detected abnormalities, namely double contour sign (DCS) and hyperechoic aggregates (HAGs), at two sites (knee and first metatarsophalangeal [1st MTP] joints) versus six sites (knee joint, 1st MTP joint, radiocarpal joint, talar joint, patellar tendon and triceps tendon) in gout patients.
Forty-seven clinically diagnosed gout patients and 50 subjects (serum uric acid < 7 mg/dL) as controls were included. 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 both the groups were compared.
Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and positive likelihood ratio (LR) of two sites ultrasound findings for gout were 87.2%, 84%, 83.7%, 85.6% and 5.5 respectively. Similar sensitivity, specificity, PPV, NPV and positive LR were observed with six sites ultrasound findings. Among controls, 16% were found to have these abnormal ultrasound findings by both two sites and six sites examinations.
Screening of two sites (knee and 1st MTP) has similar sensitivity, specificity, PPV, NPV and positive LR as compared to six sites in diagnosing gout.