Table 1. Characteristics of included studies.
| Study | Study design | Inclusion interval | Probe specifications | Qualifications of sonographers | Joints examined |
|---|---|---|---|---|---|
| Ogdie, 2017 [14] | multicenter cross-sectional study | January 2013-April 2014 | NR | all ultrasonographers had prior US training | one or more clinically affected joints |
| Das, 2017 [15] | case-control study | June,2011-December,2012 | 12–18 MHz linear probe | a rheumatologist trained in musculoskeletal US with experience for more than 4 years | both the first MTP joints and both of the knee joints |
| Elsaman, 2016 [16] | prospective single-center cross-sectional study | NR | 8–12 MHz linear probe | NR | 131 joints with arthritis (33 MTP 1 joints and 98 knee joints) |
| Loffler, 2015 [17] | retrospective cross-sectional study | NR | 7–14 MHz linear probe | sonographers trained in joint sonography and certified by the standards of the DEGUM with at least 2 years of experience in joint sonography | 225 acutely inflamed joints including knee, ankle, wrist, finger, MTP 1, shoulder, elbow joints |
| Zufferey, 2015 [18] | prospective single-center cross-sectional study | October,2012-May 2014 | 9–18 MHz | one rheumatologist with over 15 years of experience and the other with 2 years of experience | the symptomatic joints as well as both knee, ankle and MTP 1 joints |
| Leng, 2014 [19] | single-center case-control study | January 2009-December 2012 | 8–12 MHz | two sonographers with more than 6 years of experience of musculoskeletal US | knee, ankle, wrist, finger, MTP, MCP, shoulder, elbow joints |
| Lamers-Karnebeek, 2014 [20] | prospective single-center cross-sectional study | NR | 10–18 MHz and 13–14 MHz | two rheumatologists and two trainees | the joint with arthritis, the contralateral side and two other joints bilaterally |
| Gruber, 2014 [21] | prospective single-center cross-sectional study | March 2010-April 2012 | 15 or 18 MHz | two US examiners with 8 and 10 years of experience in musculoskeletal US | 37 suspected joints the hands, wrists, feet, ankles, knees and elbows |
| Naredo, 2014 [22] | multicenter case-control study | NR | 12–14 MHz liner probe | a rheumatologist highly experienced in musculoskeletal US at each center (i.e., 10–15 years of experience) | 1 joint (radiocarpal joint), 2 tendons (patellar and triceps) and 3 articular cartilages (first MTP, talar and second metacarpal/femoral) |
| Bergner, 2013 [23] | cross-sectional study | NR | NR | NR | 113 symptomatic joints including knee (n = 74), small finger or toe (n = 10), elbow (n = 5), ankle (n = 12), shoulders (n = 6) and wrists (n = 6) |
| Ottaviani, 2012 [24] | single-center case-control study | November 2008-October 2010 | 7–15 MHz multilinear probe | 2 rheumatologists trained in musculoskeletal US | The first and second MTP joints, both knees and the second and third MCP joints |
| Thiele, 2007 [25] | retrospective single-center case-control study | November 2003-December 2004 | 5–10 MHz linear probe | a rheumatologist certified in musculoskeletal US and a second rheumatologist with a short instruction period | 70 symptomatic joints including MCP, MTP 1, humero-radial, knee, shoulder, elbow joints |
| Nalbant, 2003 [26] | prospective case-control study | May 2001-October 2001 | 10–15 MHz linear probe | 2 rheumatologists trained in musculoskeletal US and experienced in using portable US | 20 nodules located on the finger, elbow, wrist and MTP joints |
DEGUM, the German Society of US in Medicine; MTP, metatarsophalangeal; MCP, metacarpophalangeal; MSU, monosodium urate; US, ultrasound; NR, not reported