The specificity of ultrasound-detected bone erosions for rheumatoid arthritis.
BACKGROUND
Bone erosion is one of the hallmarks of rheumatoid arthritis (RA), but also seen in other rheumatic diseases. The objective of this study was to determine the specificity of ultrasound (US)-detected bone erosions (including their size) in the classical 'target' joints for RA.


METHODS
Patients fulfilling the diagnostic criteria for RA, psoriatic arthritis, osteoarthritis or gout in addition to healthy volunteers were included. The following areas were examined by US: distal radius and ulna, 2nd, 3rd and 5th metacarpophalangeal (MCP), 2nd and 3rd proximal interphalangeal (PIP) and 1st and 5th metatarsophalangeal (MTP) joints. All joints were scanned in four quadrants using both semiquantitative (0-3) and quantitative (erosion diameter) scoring systems.


RESULTS
310 subjects were recruited. The inter-reader and intrareader agreements were good to excellent. US-detected bone erosions were more frequent but not specific for RA (specificity 32.9% and sensitivity 91.4%). The presence of erosions with semiquantitative score ≥2 in four target joints (2nd, 5rd MCP, 5th MTP joints and distal ulna) was highly specific for RA (specificity 97.9% and sensitivity 41.4%). Size of erosion was found to be associated with RA. Erosions of any size in the 5th MTP joint were both specific and sensitive for RA (specificity 85.4% and sensitivity 68.6%).


CONCLUSIONS
The presence of US-detected erosions is not specific for RA. However, larger erosions in selected joints, especially 2nd and 5rd MCP, 5th MTP joints and distal ulna, were highly specific for and predictive of RA.
Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds & NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds, UK.
Ahmed S
AS
Zayat
Department of Rheumatology, Parker Institute, Frederiksberg Hospital, Copenhagen, Denmark.
Karen
K
Ellegaard
Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds & NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds, UK.
Philip G
PG
Conaghan
Center for Rheumatology and Spine Diseases, Copenhagen University Hospital at Glostrup, Copenhagen, Denmark.
Lene
L
Terslev
Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds & NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds, UK.
Elizabeth M A
EM
Hensor
Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds & NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds, UK.
Jane E
JE
Freeston
Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds & NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds, UK.
Paul
P
Emery
Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds & NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds, UK.
Richard J
RJ
Wakefield
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015535:Arthritis, Psoriatic / Q000175:diagnosis / Q000000981:diagnostic imaging; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D005260:Female; D005384:Finger Joint / Q000000981:diagnostic imaging; D006073:Gout / Q000175:diagnosis / Q000000981:diagnostic imaging; D050823:Hand Joints / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008662:Metacarpophalangeal Joint / Q000000981:diagnostic imaging; D008683:Metatarsophalangeal Joint / Q000000981:diagnostic imaging*; D008875:Middle Aged; D010003:Osteoarthritis / Q000175:diagnosis / Q000000981:diagnostic imaging; D011884:Radius / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D014457:Ulna / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D014955:Wrist Joint / Q000000981:diagnostic imaging; D055815:Young Adult
Gout; Osteoarthritis; Psoriatic Arthritis; Rheumatoid Arthritis; Ultrasonography