title: Ultrasonography in gout: a case-control study.
abstract: OBJECTIVE
  To determine the sensitivity and specificity of ultrasonography for gout, and to investigate the relationship with severity of gout.
  
  
  METHODS
  In this case-control study, we prospectively enrolled 53 patients with crystal-proven gout and 50 controls. Ultrasonography was performed on 10 joints for each patient (metatarsophalangeal [MTP] joints 1-2, knees, metacarpophalangeal [MCP] joints 2-3) to determine the prevalence of the double contour (DC) sign and tophi in each site.
  
  
  RESULTS
  We assessed 530 joints in gouty patients and 500 in controls. Gouty patients had a mean disease duration 9.2±10.7 years and a mean of 14.7±19.8 acute attacks. Clinical exam revealed tophi in 44% of patients. Mean urate level was 656.7±145.3 μM. Inter-reader agreement between the 2 sonographers was excellent for both DC sign and tophi. The frequency of the DC sign in MTPs, knees and MCPs for gouty patients and controls was 67% vs. 2%, 57% vs. 0%, and 21% vs. 0%, respectively (all p<0.001), whereas that of tophi, only found in gouty patients, was 74%, 42% and 22%, respectively (p<0.001). The sensitivity of the DC sign was 67% for MTPs, 57% for knees and 21% for MCPs, and specificity was high (all >98%). The sensitivity of tophi was 74%, 42% and 22%, respectively, and specificity 100% for all sites. For MTPs, the DC sign, but not tophi, was significantly associated with uricemia (p<0.05) and disease duration (p=0.01).
  
  
  CONCLUSIONS
  Ultrasonography has good sensitivity and specificity to diagnose gout. Sensitivity depends on disease duration, joint site and severity of the disease.
authors.affiliation: Université Paris Diderot, Assistance Publique-Hôpitaux de Paris, Hôpital Lariboisière, Fédération de Rhumatologie, Paris, France. sebastien.ottaviani@bch.aphp.fr
authors.forename: Sébastien
authors.initials: S
authors.lastname: Ottaviani
authors.forename: Pascal
authors.initials: P
authors.lastname: Richette
authors.forename: Anne
authors.initials: A
authors.lastname: Allard
authors.forename: Jérémy
authors.initials: J
authors.lastname: Ora
authors.forename: Thomas
authors.initials: T
authors.lastname: Bardin
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006073:Gout / Q000000981:diagnostic imaging* / Q000453:epidemiology; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging; D008297:Male; D008662:Metacarpophalangeal Joint / Q000000981:diagnostic imaging; D008683:Metatarsophalangeal Joint / Q000000981:diagnostic imaging; D008875:Middle Aged; D015588:Observer Variation; D015995:Prevalence; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014463:Ultrasonography / Q000379:methods* / Q000592:standards* / Q000706:statistics & numerical data