Poster (15A159)

Radiologist versus Rheumatologist: Interpretation of Erosive Change on Plain Film Radiographs in RA

Author(s)

Orr C, Najm A, Young F, Veale DJ

Department(s)/Institutions

Centre for Arthritis and Rheumatic Diseases, Dublin Academic Medical Centre, University College Dublin, Ireland.

Introduction

RA is characterised by progressive changes in bone architecture characterised primarily by the development of erosions, which later lead to deformity and disability[1] Identifying and monitoring erosive changes on plain film radiographs in patients with RA remains the ‘gold-standard’ in assessing disease progression over time.[2] Rheumatologists often use the radiologist’s reports in diagnosis and follow up of RA patients. How these reports in routine clinical practice compare with the formal assessment of radiographs using the validated Sharp/van der Heijde scoring (SHS) methods by rheumatologists[3] have not previously been reported.

Aims/Background

To determine the agreement between radiologist report and rheumatologist SHS of plain film radiographs for the presence or absence of erosions.

Method

54 sets of hands and feet radiographs of patients with RA were scored by two rheumatologists separately. Following this, the reports of the radiologists were examined to determine if there was erosive disease. The erosion component of the SHS amounts to a maximum of 280 points, and erosions were considered present if the score was >5.

Results

The results are outlined in Table 1. Agreement between the radiologists and rheumatologists regarding bone erosions was achieved in 37 sets of radiographs (68.5%), with no instances of radiologists reporting erosions that were not identified by the rheumatologists.

Conclusions

Nearly 70% of radiographs were agreed on. There were no radiographs judged to have erosions by radiology, but not by rheumatology, indicating that rheumatologists applying the SHS are more sensitive to identifying erosions. It is also worth noting that the mean score for the presence of erosions identified by rheumatologists but not radiologists was 13.71 (Std. Dev 6.28). Of a total erosion score of 280, this is very small. Furthermore, the clinical relevance of erosive scores this low is not clear. Smolen et al have shown that an increase in Sharp Score of a single point is approximately the equivalent of a change in HAQ score of 0.01.[4] A change in HAQ score of 0.19-0.23 is required before a change in function is observed[5] and this means that an increase of 19-23 points are expected to be necessary before this would have a clinically meaningful effect.