QUANTITATIVE MEASUREMENT OF EROSION GROWTH AND JOINT SPACE LOSS IN RHEUMATOID-ARTHRITIS HAND RADIOGRAPHS

Objective. To evaluate the performance of simple, inexpensive quantita tive techniques for measuring erosion growth and joint space loss in s erial hand radiographs of patients with rheumatoid arthritis (RA). Met hods. Erosions were measured using a plastic overlay template of sampl e erosion sizes. Joint spaces were measured with a hand held measuring micrometer. In the first phase of testing, a spectrum of individual e rosions and joint spaces was measured to determine intra and interobse rver correlations and variability. In the 2nd phase, the tools were us ed to measure serial changes in RA hand radiographs. Observer correlat ions and the ability to discriminate serial changes were determined an d compared to the scoring method of Sharp. Results. Measurements of in dividual erosion areas and joint spaces were highly reproducible. Intr a and interobserver correlations were significant (p < 0.05) for seria l erosion growth and joint space loss measurements, as well as changes in Sharp scores; Quantitative measurements correlated highly with the corresponding Sharp score changes. Of all measurements or scores reco rded, quantitative joint space loss measurements were statistically su perior in discriminating serial change in RA hand radiographs. Quantit atively measured joint space loss correlated well with both erosion gr owth measurements and serial change in total Sharp scores. Conclusion. Quantitative measurement of erosion growth and joint space loss is po ssible with simple inexpensive techniques. Further study is needed to confirm our data, which suggest that quantitative measurement of joint space narrowing may be the most useful discriminator of serial change s in RA hand radiographs.