Ultrasound as an Outcome Measure in Gout. A Validation Process by the OMERACT Ultrasound Working Group.
OBJECTIVE
To summarize the work performed by the Outcome Measures in Rheumatology (OMERACT) Ultrasound (US) Working Group on the validation of US as a potential outcome measure in gout.


METHODS
Based on the lack of definitions, highlighted in a recent literature review on US as an outcome tool in gout, a series of iterative exercises were carried out to obtain consensus-based definitions on US elementary components in gout using a Delphi exercise and subsequently testing these definitions in static images and in patients with proven gout. Cohen's κ was used to test agreement, and values of 0-0.20 were considered poor, 0.20-0.40 fair, 0.40-0.60 moderate, 0.60-0.80 good, and 0.80-1 excellent.


RESULTS
With an agreement of > 80%, consensus-based definitions were obtained for the 4 elementary lesions highlighted in the literature review: tophi, aggregates, erosions, and double contour (DC). In static images interobserver reliability ranged from moderate to almost perfect, and similar results were found for the intrareader reliability. In patients the intraobserver agreement was good for all lesions except DC (moderate). The interobserver agreement was poor for aggregates and DC but moderate for the other components.


CONCLUSIONS
These first steps in evaluating the validity of US as an outcome measure for gout show that the reliability of the definitions ranged from moderate to excellent in static images and somewhat lower in patients, indicating that a standardized scanning technique may be needed, before testing the responsiveness of those definitions in a composite US score.
Lene
L
Terslev
Marwin
M
Gutierrez
Wolfgang A
WA
Schmidt
Helen I
HI
Keen
Emilio
E
Filippucci
David
D
Kane
Ralf
R
Thiele
Gurjit
G
Kaeley
Peter
P
Balint
Peter
P
Mandl
Andrea
A
Delle Sedie
Hilde Berner
HB
Hammer
Robin
R
Christensen
Ingrid
I
Möller
Carlos
C
Pineda
Eugene
E
Kissin
George A
GA
Bruyn
Annamaria
A
Iagnocco
Esperanza
E
Naredo
Maria Antonietta
MA
D'Agostino
D003245:Consensus Statements as Topic; D003697:Delphi Technique; D018450:Disease Progression; D005260:Female; D005602:France; D006073:Gout / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D017063:Outcome Assessment, Health Care; D018608:Ultrasonography, Doppler / Q000592:standards*
GOUT; REPRODUCIBILITY OF RESULTS; ULTRASOUND