title: Diagnostic utility of musculoskeletal ultrasound in patients with suspected arthritis--a probabilistic approach.
abstract: BACKGROUND
  This study aimed to assess the utility of musculoskeletal ultrasound (MSUS) in patients with joint symptoms using a probabilistic approach.
  
  
  METHODS
  One hundred and three patients without prior rheumatologic diagnosis and referred to our clinic for evaluation of inflammatory arthritis were included. Patients were assessed clinically including joint examination, laboratory testing including acute-phase reactants, rheumatoid factor (RF) and anti citrulinated protein antibody (ACPA), and radiographs of hands and feet if clinically indicated. A diagnostic assessment was then performed by the responsible rheumatologist where the probability of a) any inflammatory arthritis and b) rheumatoid arthritis was given on a 5-point scale ranging from 0 to 20% up to 80 to 100% probability. Subsequently, an ultrasound examination of the wrist, metacarpophalangeal (MCP), proximal interphalangeal (PIP) joints 2 to 5 in both hands, metatarsophalangeal (MTP) joints 2 to 5 in both feet and any symptomatic joints was performed and the results presented to the same rheumatologist. The latter then assessed the diagnostic probabilities again, using the same scale.
  
  
  RESULTS
  The rheumatologists' certainty for presence/absence of inflammatory arthritis and rheumatoid arthritis was increased significantly following ultrasound performance. The proportion of patient for whom diagnostic certainty for inflammatory arthritis was maximal was 33.0% before and 71.8% after musculoskeletal ultrasound (P <0.001). With regard to a diagnosis of RA, the proportions were 31.1% pre-test and 61.2% post-test (P <0.001). MSUS findings agreed with the final diagnosis in 95% of patients.
  
  
  CONCLUSIONS
  Musculoskeletal ultrasound, when added to routine rheumatologic investigation, greatly increases the diagnostic certainty in patients referred for the evaluation of inflammatory arthritis. The changes from pre-test to post-test probability quantify the diagnostic utility of musculoskeletal ultrasound in probabilistic terms.
authors.forename: Hamed
authors.initials: H
authors.lastname: Rezaei
authors.forename: Søren
authors.initials: S
authors.lastname: Torp-Pedersen
authors.forename: Erik
authors.initials: E
authors.lastname: af Klint
authors.forename: Magnus
authors.initials: M
authors.lastname: Backheden
authors.forename: Yogan
authors.initials: Y
authors.lastname: Kisten
authors.forename: Noémi
authors.initials: N
authors.lastname: Györi
authors.forename: Ronald F
authors.initials: RF
authors.lastname: van Vollenhoven
mesh_terms: D000209:Acute-Phase Proteins / Q000032:analysis; D000328:Adult; D000368:Aged; D001168:Arthritis / Q000175:diagnosis*; D001172:Arthritis, Rheumatoid / Q000175:diagnosis*; D005384:Finger Joint / Q000000981:diagnostic imaging; D006801:Humans; D008683:Metatarsophalangeal Joint / Q000000981:diagnostic imaging; D008875:Middle Aged; D009141:Musculoskeletal System / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D011336:Probability; D015203:Reproducibility of Results; D012217:Rheumatoid Factor / Q000032:analysis; D012680:Sensitivity and Specificity; D018615:Ultrasonography, Doppler, Color / Q000379:methods*; D014955:Wrist Joint / Q000000981:diagnostic imaging
chemical_list: D000209:Acute-Phase Proteins; D012217:Rheumatoid Factor