Validation of a radiographic damage index in chronic gout.
OBJECTIVE
To identify a valid method to measure radiographic damage in patients with chronic gout.


METHODS
The scoring method that best represented radiographic damage in individual joints was analyzed by comparing a gold standard rheumatologist consensus global score with recognized scoring methods, including the Sharp/van der Heijde erosion and narrowing scores, Ratingen destruction score, and Steinbrocker score. Ninety-five proximal interphalangeal joints from 12 patients with gout were included in this analysis. Scoring of hand and feet radiographs from an additional 35 patients with gout was used to analyze the sites to be included in a scoring system and the additional features to be recorded.


RESULTS
For individual joints, the combination of the Sharp/van der Heijde erosion and narrowing scores correlated best with the consensus global score. In addition, the limits of agreement were narrowest for the combined Sharp/van der Heijde erosion and narrowing score. All joint areas in the Sharp/van der Heijde rheumatoid arthritis score and the distal interphalangeal joints were affected by chronic gout and contributed to the total score. Additional features (extraarticular erosions, joint space widening, and ankylosis) occurred infrequently, and scoring of these features did not increase the reliability of the total score. The reliability of the total score was high: intraclass correlation coefficient for intraobserver reproducibility was 0.993-0.998 and for interobserver reproducibility was 0.963-0.966. The modified Sharp/van der Heijde score was able to discriminate between early and advanced disease.


CONCLUSIONS
A modified Sharp/van der Heijde system accurately and reliably represents radiographic joint damage in chronic gout.
Dalbeth
Nicola
N
University of Auckland, Grafton, Auckland, New Zealand. n.dalbeth@auckland.ac.nz
Clark
Barnaby
B
McQueen
Fiona
F
Doyle
Anthony
A
Taylor
William
W
D002908:Chronic Disease; D004185:Disability Evaluation; D005384:Finger Joint / Q000000981:diagnostic imaging / Q000473:pathology; D006073:Gout / Q000000981:diagnostic imaging* / Q000473:pathology*; D006801:Humans; D017063:Outcome Assessment, Health Care; D011859:Radiography; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014033:Toe Joint / Q000000981:diagnostic imaging / Q000473:pathology