Performance of an automated computer-based scoring method to assess joint space narrowing in rheumatoid arthritis: a longitudinal study.
OBJECTIVE
To compare the diagnostic performance of a computer-based method for measuring joint space width with the Sharp joint space narrowing (JSN) scoring method in patients with rheumatoid arthritis (RA).


METHODS
A random sample of patients with early RA, for whom sequential hand radiographs and Sharp scores were available, was selected from the National Data Bank for Rheumatic Diseases. Hand joint space width was measured using an automated, computer-based method in random order and with blinding for clinical information. We constructed a receiver operating characteristic curve and compared the diagnostic performance of the computer-based and Sharp methods based on the areas under the curve.


RESULTS
One hundred twenty-nine patients with early RA who underwent serial radiography were included. Changes in the computer-based and Sharp methods were highly correlated (r = 0.75, P < 0.001). The computer-based method was significantly more discriminant than the Sharp JSN subscale. The area under the curve of the computer-based method was 0.96 (95% confidence interval [95% CI] 0.94, 0.99) compared with 0.93 (95% CI 0.89, 0.96) for the Sharp subscale (P = 0.024). At the most discriminant cutoff, specificity of the computer-based method was 88.4% compared with 81.4% for the Sharp subscale (P = 0.11); sensitivity was 87.6% for the computer-based method compared with 82.2% for Sharp subscale (P = 0.19). The signal-to-noise ratio for the computer-based method was 83% compared with 70% for the Sharp subscale (P = 0.013).


CONCLUSIONS
The computer-based method for measuring joint space width is more discriminant than the semiquantitative Sharp JSN subscale.
Finckh
Axel
A
Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA. afinckh@post.harvard.edu
de Pablo
Paola
P
Katz
Jeffrey N
JN
Neumann
Gesa
G
Lu
Ying
Y
Wolfe
Frederick
F
Duryea
Jeffrey
J
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging*; D003936:Diagnosis, Computer-Assisted; D005260:Female; D005384:Finger Joint / Q000000981:diagnostic imaging*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011859:Radiography; D015203:Reproducibility of Results