Interobserver variation in the evaluation of radiologic changes of rheumatoid arthritis.

The variation between four radiologists in the evaluation of hand, wrist, and foot radiographs of rheumatoid arthritis was examined. The recognition of individual radiologic changes varied considerably as judged by the findings of the different observers. Erosion and joint space narrowing were interpreted more uniformly than soft tissue swelling and osteoporosis. When the radiographs were graded from 0 to 5 using standard reference radiographs, more than 90% of them were graded uniformly or with a difference of only one grade. The investigation has shown that when applying grading of rheumatoid arthritis according to standard reference radiographs, the interobserver variation is considerably less than when pure individual radiological changes of rheumatoid arhtritis are considered.