Radiographic assessment of sacroiliitis by radiologists and rheumatologists: does training improve quality?

Abstract

Objective: To assess performance of radiologists and rheumatologists in detecting sacroiliitis Methods: 100 rheumatologists and 23 radiologists participated. One set of films was used for each assessment, another for training, and the third for confidence judgment. Films of HLA-B27+ patients with AS were used to assess sensitivity. For specificity films of healthy HLA-B27− relatives were included. Plain sacroiliac (SI) films with simultaneously taken computed tomographic scans (CTs) were used for confidence judgment. Three months after reading the training set, sensitivity and specificity assessments were repeated. Next, participants attended a workshop. They also rated 26 SI radiographs and 26 CTs for their trust in each judgment. Three months later final assessments were done. Results: Sensitivity (84.3%/79.8%) and specificity (70.6%/74.7%) for radiologists and rheumatologists were comparable. Rheumatologists showed 6.3% decrease in sensitivity after self education (p=0.001), but 3.0% better specificity (p=0.008). The decrease in sensitivity reversed after the workshop. Difference in sensitivity three months after the workshop and baseline was only 0.5%. Sensitivity <50% occurred in 13% of participants. Only a few participants showed changes of >5% in both sensitivity and specificity. Intraobserver agreement for sacroiliitis grade 1 or 2 ranged from 65% to 100%. Sensitivity for CT (86%) was higher than for plain films (72%) (p<0.001) with the same specificity (84%). Confidence ratings for correctly diagnosing presence (7.7) or absence (8.3) of sacroiliitis were somewhat higher than incorrectly diagnosing the presence (6.6) or absence (7.4) of sacroiliitis (p<0.001). Conclusion: Radiologists and rheumatologists show modest sensitivity and specificity for sacroiliitis and sizeable intraobserver variation. Overall, neither individual training nor workshops improved performance.A nkylosing spondylitis (AS) is a chronic inflammatory disease, in which predominantly the axial skeleton is affected. Sacroiliitis is considered as the hallmark of the disease. Involvement of the sacroiliac (SI) joints is usually established by plain radiographs, or-to a lesser degree-by computed tomography scan (CT) or magnetic resonance imaging (MRI). Rheumatologists in daily practice mostly order plain radiographs for diagnosing sacroiliitis, and they often read these films themselves. Radiologists read and report radiographs of SI joints examinations requested by rheumatologists, general practitioners, or orthopaedic surgeons. Reading radiographs of the SI joints is considered difficult and the diagnosis of sacroiliitis is often missed or incorrectly established. Inter-and intraobserver variations have been reported to be large. 1-3κ Statistics to express intraobserver variation in these studies ranged from 0.07 to 1.0 2 3 and interobserver variation from 0.19 to 0.79. 1-3We questioned whether the performance of radiologists and rheumatologists in reading SI radiographs differs, and whether this performance might be improved by offerin...

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