Downloaded from ard.bmj.com on April 3, 2014 - Published by group.bmj.com
ARD Online First, published on January 20, 2014 as 10.1136/annrheumdis-2013-204864 Clinical and epidemiological research
EXTENDED REPORT
The specificity of ultrasound-detected bone erosions for rheumatoid arthritis Ahmed S Zayat,1 Karen Ellegard,2 Philip G Conaghan,1 Lene Terslev,3 Elizabeth M A Hensor,1 Jane E Freeston,1 Paul Emery,1 Richard J Wakefield1 Handling editor Tore K Kvien ▸ Additional material is published online only. To view please visit the journal online (http://dx.doi.org/10.1136/ annrheumdis-2013-204864). 1
Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds & NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds, UK 2 Department of Rheumatology, Parker Institute, Frederiksberg Hospital, Copenhagen, Denmark 3 Center for Rheumatology and Spine Diseases, Copenhagen University Hospital at Glostrup, Copenhagen, Denmark Correspondence to Dr Ahmed S Zayat, Leeds Institute of Rheumatic and Musculoskeletal Medicine (LIRMM), Second Floor, Chapel Allerton Hospital, Leeds LS7 4SA, UK; [email protected]. uk Received 8 November 2013 Revised 23 December 2013 Accepted 27 December 2013
ABSTRACT 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.
INTRODUCTION
To cite: Zayat AS, Ellegard K, Conaghan PG, et al. Ann Rheum Dis Published Online First: [please include Day Month Year] doi:10.1136/ annrheumdis-2013-204864
Bone erosions are commonly considered to be the hallmark of rheumatoid arthritis (RA).1 They represent a destructive consequence of untreated synovitis and osteitis. One of the major goals in the treatment of RA is the arrest of erosion development in order to prevent irreversible functional disability.2 Until recently, the presence of radiographic bone erosions was one of the American College of Rheumatologist (ACR) 1987 classification criteria for RA.3 The new ACR/European League Against Rheumatism (EULAR) 2010 criteria allow the diagnosis of RA in the presence of typical erosions even without fulfilment of the other criteria within the scoring system.4 New more sensitive imaging techniques such as ultrasound (US) are increasingly used in disease assessment. Although US is more sensitive than conventional radiography (CR) for detecting bone erosions,5 there are limited data regarding the
specificity of US-detected bone erosions for RA in comparison with other arthritides. There are also limited data about the effect of location, size and severity of erosion on US specificity. The objective of this study was to investigate the discriminative ability of US by studying the specificity of US-detected bone erosions for RA. We aimed to determine: (a) if the frequency of US-detected bone erosions in RA is significantly higher than other arthritis groups and normal controls, (b) the specificity of US-detected erosions in suggested target joints for RA and (c) the effect of erosion size and location on their specificity for RA.
PATIENTS AND METHODS The study was conducted at two sites, Leeds and Copenhagen.
Patients Patients fulfilling the diagnostic criteria for RA, psoriatic arthritis (PsA), osteoarthritis (OA) and gout were included in the study.3 6 7 During the screening process, patients with mono/oligo-articular PsA or knees/hip OA alone were not included as we aimed for polyarticular disease. Subjects who had undergone arthroplasty in their hands or feet, those with a diagnosis of more than one type of arthritis, undifferentiated arthritis or those who did not meet the diagnostic criteria of any of the included diseases were excluded. A group of healthy controls (HCs) without a history suggestive of arthritis was also included. The study was approved by the local ethics committees at both centres and informed written consent was obtained from all patients and healthy volunteers before study enrolment.
Ultrasonographic examination Ultrasonography was performed at both sites using a General Electric Logiq E9 US machine (General Electric, Wauwatosa, Wisconsin, USA) with a multilinear 6–15 MHz probe. Two investigators (ASZ and KE) trained in musculoskeletal US performed all examinations either at Chapel Allerton Hospital, Leeds, UK or Copenhagen University Hospital at Glostrup, Copenhagen, Denmark, respectively. The investigators were blinded to clinical diagnosis and findings. The following joints or bony areas were examined bilaterally in each patient; distal articular radius and ulna including caput and styloid processes, 2nd, 3rd and 5th metacarpophalangeal (MCP), 2nd and 3rd proximal interphalangeal and 1st and 5th metatarsophalangeal (MTP) joints. Joints were examined both
Zayat AS, et al. Ann Rheum Dis 2014;0:1–7. 1 Copyright Article author (or theirdoi:10.1136/annrheumdis-2013-204864 employer) 2014. Produced by BMJ Publishing Group Ltd (& EULAR) under licence.
Downloaded from ard.bmj.com on April 3, 2014 - Published by group.bmj.com
Clinical and epidemiological research Heteroskedasticity-robust quantile regression was used to compare the erosion scores and maximum erosion diameters between groups. Models were adjusted for age and centre, which was treated as a fixed factor. Receiver Operating Characteristics (ROC) analysis was used to identify cut-offs for erosion diameter which concurrently maximised sensitivity and specificity and/or maximised the Youden index J (sensitivity+specificity − 1) for different diagnoses. Analysis was performed twice, once with normal subjects included and once when they were excluded. The interobserver and intraobserver reliability of the semiquantitative scores was assessed using quadratic-weighted κ (κw) statistics.9
RESULTS Patient demographics
Figure 1 Scoring method of bone erosion. Each bone surface was divided into ‘virtual’ quadrants on transverse view. The degree of bone affected determined the score given. 0=no erosions, 1=erosions covering ⅔ of the surface of the quadrant.
A total of 310 subjects were recruited including 70 RA, 60 PsA, 60 gout, 60 OA and 60 healthy volunteers. In all, 188 (61%) were women. The RA group consisted of 28 patients with early RA and 42 patients with established RA (table 1). In all, 80% of the patients were positive to either rheumatoid factor or anticitrullinated protein antibodies.
US assessment Reliability proximally and distally to the joint margin. All joints were scanned in quadrants (figure 1). Each scan was performed in longitudinal and transverse planes. An erosion was defined as a discontinuity of the cortical bone surface that was visualised in at least two perpendicular planes according to the OMERACT definition.8 Each quadrant was scored using a transverse view according to a 0–3 semiquantitative scoring system: 0=no erosions, 1=erosions covering less than a third of the surface of the quadrant, 2=erosions covering between one- to two-thirds of the surface of the quadrant and 3=erosions covering more than two-thirds of the surface of the quadrant (figure 2). A total score of 0–3 was then given to each joint (proximal or distal) by summing the joint quadrants scores and dividing by four. The diameter of the largest erosion in each joint (proximal or distal) was recorded mostly on longitudinal view unless maximum diameter was provided by transverse view. The inter-observer and intraobserver reliability were tested by rescoring 50 static US images by both observers in both centres in two occasions blindly.
Statistical analysis Statistical analysis was performed using Stata V.12.1 and WinPEPI 11.4. Sample size was based on attaining a desired 95% CI of ±5% around an estimate of specificity of 90%. When counting the number of joints with erosions present, the proximal and distal regions of joints were counted separately. To assess the overall differences in the number of erosions between disease groups, negative binomial regression with robust SEs was used.
The inter-centre agreement was excellent (κw (95% CI) 0.88 (0.76 to 1.00), p0) than patients with PsA (incident rate ratio (95% CI) 2.50 (1.87 to 3.35), p0 DU/MCP2, 5/MTP5‡ Erosion score≥2 DU/MCP2, 5/MTP5‡ Erosion score>0 proximal MTP5 ‡ Erosion score≥2 proximal MTP5‡
4 (2 to 6) 0 (0 to 1) 4 (2 to 7) 2.7 (1.3 to 4.6) 2.3 (0.7 to 4.5) 25 (89.3%) 7 (25.0%) 21 (75.0%) 5 (17.9%) 15 (53.6%) 5 (17.9%)
7 (3 to 10) 1 (0 to 3) 9 (4 to 14) 3.3 (2.5 to 5.3) 2.9 (1.9 to 3.7) 39 (92.9%) 28 (66.7%) 36 (85.7%) 24 (57.1%) 33 (78.6%) 20 (47.6%)
IRR 1.75 (1.29–2.39), p0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Max diameter≥2.5 mm Erosion score>0 Erosion score≥2 Max diameter≥2.5 mm
25.7 (16.9 to 37.0) 8.6 (4.0 to 17.5) 20.0 (12.3 to 30.8) 4.3 (1.5 to 11.9) 47.1 (35.9 to 58.7) 14.3 (7.9 to 24.3) 24.3 (15.8 to 35.5) 11.4 (5.9 to 21.0) 40.0 (29.3 to 51.7) 5.7 (2.2 to 13.8) 47.1 (35.9 to 58.7) 2.9 (0.8 to 1.0) 37.1 (26.8 to 48.9) 7.1 (3.1 to 15.7) 61.4 (49.7 to 72.0) 18.6 (11.2 to 29.2) 68.6 (57.0 to 78.2) 35.7 (25.5 to 47.4) 91.4 (82.5 to 96.0) 50.0 (38.6 to 61.4) 68.6 (57.0 to 78.2) 81.4 (70.8 to 88.8) 41.4 (30.6 to 53.1) 58.6 (46.9 to 69.4)
10.7 (3.7 to 27.2) 3.6 (0.6 to 17.7) 10.7 (3.7 to 27.2) 0 (0 to 12.1) 42.9 (26.5 to 60.9) 3.6 (0.6 to 17.7) 10.7 (3.7 to 27.2) 3.6 (0.6 to 17.7) 35.7 (20.7 to 54.2) 0 (0 to 12.1) 39.3 (23.6 to 57.6) 3.6 (0.6 to 17.7) 14.3 (5.7 to 31.5) 3.6 (0.6 to 17.7) 46.4 (29.5 to 64.2) 7.1 (2.0 to 22.6) 53.5 (35.8 to 70.5) 17.9 (7.9 to 35.6) 89.3 (72.8 to 96.3) 25.0 (12.7 to 43.4) 57.1 (39.1 to 73.5) 75.0 (56.6 to 87.3) 17.8 (7.9 to 35.6) 50.0 (32.6 to 67.4)
87.9 (83.2 96.7 (93.6 86.7 (81.8 96.3 (93.0 87.1 (82.2 99.6 (97.7 96.7 (93.6 99.6 (97.8 94.6 (91.0 100 (98.4 70.0 (63.9 100 (98.4 89.6 (85.1 99.6 (97.7 69.6 (63.5 96.7 (93.6 85.4 (80.4 98.8 (96.4 32.9 (28.3 89.2 (84.6 75.8 (70.0 68.8 (62.6 97.9 (95.2 90.0 (85.6
84.4 (78.4 95.6 (91.5 82.2 (76.0 95.0 (90.8 83.3 (77.2 99.4 (96.9 95.6 (91.5 99.4 (96.9 92.8 (88.0 100 (97.9 66.7 (59.5 100 (97.9 86.1 (80.3 99.4 (96.9 62.8 (55.5 95.6 (91.5 81.7 (75.4 98.3 (95.2 21.7 (16.3 85.6 (79.7 68.3 (61.2 60.0 (52.7 97.2 (93.7 86.7 (80.9
to to to to to to to to to to to to to to to to to to to to to to to to
91.5) 98.3) 90.4) 98.0) 90.7) 99.9) 98.3) 99.9) 96.8) 100) 75.4) 100) 92.8) 99.9) 75.1) 98.3) 89.3) 99.6) 39.1) 92.5) 80.8) 74.3) 99.1) 93.2)
to to to to to to to to to to to to to to to to to to to to to to to to
89.0) 97.7) 87.1) 97.3) 88.1) 99.9) 97.7) 99.9) 95.7) 100) 73.1) 100) 90.4) 99.9) 69.5) 97.7) 86.6) 99.4) 28.2) 89.9) 74.7) 66.9) 98.8) 90.9)
*US/MCP2, 5/MTP5= distal ulna, 2nd and 5th MCP joints and 5th MTP joint all together. DU, distal ulna; MCP, metacarpophalangeal; MTP, metatarsophalangeal; PIP, proximal interphalangeal; RA, rheumatoid arthritis.
When looking at what size of erosion was predictive and specific for RA, ROC analysis (HC excluded) indicated that the diameter of the largest erosion in the distal ulna, 2nd MCP, 5th MCP and 5th MTP joints was predictive of RA (area under the ROC curve (95% CI) 0.78 (0.71 to 0.84), p
ARD Online First, published on January 20, 2014 as 10.1136/annrheumdis-2013-204864 Clinical and epidemiological research
EXTENDED REPORT
The specificity of ultrasound-detected bone erosions for rheumatoid arthritis Ahmed S Zayat,1 Karen Ellegard,2 Philip G Conaghan,1 Lene Terslev,3 Elizabeth M A Hensor,1 Jane E Freeston,1 Paul Emery,1 Richard J Wakefield1 Handling editor Tore K Kvien ▸ Additional material is published online only. To view please visit the journal online (http://dx.doi.org/10.1136/ annrheumdis-2013-204864). 1
Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds & NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds, UK 2 Department of Rheumatology, Parker Institute, Frederiksberg Hospital, Copenhagen, Denmark 3 Center for Rheumatology and Spine Diseases, Copenhagen University Hospital at Glostrup, Copenhagen, Denmark Correspondence to Dr Ahmed S Zayat, Leeds Institute of Rheumatic and Musculoskeletal Medicine (LIRMM), Second Floor, Chapel Allerton Hospital, Leeds LS7 4SA, UK; [email protected]. uk Received 8 November 2013 Revised 23 December 2013 Accepted 27 December 2013
ABSTRACT 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.
INTRODUCTION
To cite: Zayat AS, Ellegard K, Conaghan PG, et al. Ann Rheum Dis Published Online First: [please include Day Month Year] doi:10.1136/ annrheumdis-2013-204864
Bone erosions are commonly considered to be the hallmark of rheumatoid arthritis (RA).1 They represent a destructive consequence of untreated synovitis and osteitis. One of the major goals in the treatment of RA is the arrest of erosion development in order to prevent irreversible functional disability.2 Until recently, the presence of radiographic bone erosions was one of the American College of Rheumatologist (ACR) 1987 classification criteria for RA.3 The new ACR/European League Against Rheumatism (EULAR) 2010 criteria allow the diagnosis of RA in the presence of typical erosions even without fulfilment of the other criteria within the scoring system.4 New more sensitive imaging techniques such as ultrasound (US) are increasingly used in disease assessment. Although US is more sensitive than conventional radiography (CR) for detecting bone erosions,5 there are limited data regarding the
specificity of US-detected bone erosions for RA in comparison with other arthritides. There are also limited data about the effect of location, size and severity of erosion on US specificity. The objective of this study was to investigate the discriminative ability of US by studying the specificity of US-detected bone erosions for RA. We aimed to determine: (a) if the frequency of US-detected bone erosions in RA is significantly higher than other arthritis groups and normal controls, (b) the specificity of US-detected erosions in suggested target joints for RA and (c) the effect of erosion size and location on their specificity for RA.
PATIENTS AND METHODS The study was conducted at two sites, Leeds and Copenhagen.
Patients Patients fulfilling the diagnostic criteria for RA, psoriatic arthritis (PsA), osteoarthritis (OA) and gout were included in the study.3 6 7 During the screening process, patients with mono/oligo-articular PsA or knees/hip OA alone were not included as we aimed for polyarticular disease. Subjects who had undergone arthroplasty in their hands or feet, those with a diagnosis of more than one type of arthritis, undifferentiated arthritis or those who did not meet the diagnostic criteria of any of the included diseases were excluded. A group of healthy controls (HCs) without a history suggestive of arthritis was also included. The study was approved by the local ethics committees at both centres and informed written consent was obtained from all patients and healthy volunteers before study enrolment.
Ultrasonographic examination Ultrasonography was performed at both sites using a General Electric Logiq E9 US machine (General Electric, Wauwatosa, Wisconsin, USA) with a multilinear 6–15 MHz probe. Two investigators (ASZ and KE) trained in musculoskeletal US performed all examinations either at Chapel Allerton Hospital, Leeds, UK or Copenhagen University Hospital at Glostrup, Copenhagen, Denmark, respectively. The investigators were blinded to clinical diagnosis and findings. The following joints or bony areas were examined bilaterally in each patient; distal articular radius and ulna including caput and styloid processes, 2nd, 3rd and 5th metacarpophalangeal (MCP), 2nd and 3rd proximal interphalangeal and 1st and 5th metatarsophalangeal (MTP) joints. Joints were examined both
Zayat AS, et al. Ann Rheum Dis 2014;0:1–7. 1 Copyright Article author (or theirdoi:10.1136/annrheumdis-2013-204864 employer) 2014. Produced by BMJ Publishing Group Ltd (& EULAR) under licence.
Downloaded from ard.bmj.com on April 3, 2014 - Published by group.bmj.com
Clinical and epidemiological research Heteroskedasticity-robust quantile regression was used to compare the erosion scores and maximum erosion diameters between groups. Models were adjusted for age and centre, which was treated as a fixed factor. Receiver Operating Characteristics (ROC) analysis was used to identify cut-offs for erosion diameter which concurrently maximised sensitivity and specificity and/or maximised the Youden index J (sensitivity+specificity − 1) for different diagnoses. Analysis was performed twice, once with normal subjects included and once when they were excluded. The interobserver and intraobserver reliability of the semiquantitative scores was assessed using quadratic-weighted κ (κw) statistics.9
RESULTS Patient demographics
Figure 1 Scoring method of bone erosion. Each bone surface was divided into ‘virtual’ quadrants on transverse view. The degree of bone affected determined the score given. 0=no erosions, 1=erosions covering ⅔ of the surface of the quadrant.
A total of 310 subjects were recruited including 70 RA, 60 PsA, 60 gout, 60 OA and 60 healthy volunteers. In all, 188 (61%) were women. The RA group consisted of 28 patients with early RA and 42 patients with established RA (table 1). In all, 80% of the patients were positive to either rheumatoid factor or anticitrullinated protein antibodies.
US assessment Reliability proximally and distally to the joint margin. All joints were scanned in quadrants (figure 1). Each scan was performed in longitudinal and transverse planes. An erosion was defined as a discontinuity of the cortical bone surface that was visualised in at least two perpendicular planes according to the OMERACT definition.8 Each quadrant was scored using a transverse view according to a 0–3 semiquantitative scoring system: 0=no erosions, 1=erosions covering less than a third of the surface of the quadrant, 2=erosions covering between one- to two-thirds of the surface of the quadrant and 3=erosions covering more than two-thirds of the surface of the quadrant (figure 2). A total score of 0–3 was then given to each joint (proximal or distal) by summing the joint quadrants scores and dividing by four. The diameter of the largest erosion in each joint (proximal or distal) was recorded mostly on longitudinal view unless maximum diameter was provided by transverse view. The inter-observer and intraobserver reliability were tested by rescoring 50 static US images by both observers in both centres in two occasions blindly.
Statistical analysis Statistical analysis was performed using Stata V.12.1 and WinPEPI 11.4. Sample size was based on attaining a desired 95% CI of ±5% around an estimate of specificity of 90%. When counting the number of joints with erosions present, the proximal and distal regions of joints were counted separately. To assess the overall differences in the number of erosions between disease groups, negative binomial regression with robust SEs was used.
The inter-centre agreement was excellent (κw (95% CI) 0.88 (0.76 to 1.00), p0) than patients with PsA (incident rate ratio (95% CI) 2.50 (1.87 to 3.35), p0 DU/MCP2, 5/MTP5‡ Erosion score≥2 DU/MCP2, 5/MTP5‡ Erosion score>0 proximal MTP5 ‡ Erosion score≥2 proximal MTP5‡
4 (2 to 6) 0 (0 to 1) 4 (2 to 7) 2.7 (1.3 to 4.6) 2.3 (0.7 to 4.5) 25 (89.3%) 7 (25.0%) 21 (75.0%) 5 (17.9%) 15 (53.6%) 5 (17.9%)
7 (3 to 10) 1 (0 to 3) 9 (4 to 14) 3.3 (2.5 to 5.3) 2.9 (1.9 to 3.7) 39 (92.9%) 28 (66.7%) 36 (85.7%) 24 (57.1%) 33 (78.6%) 20 (47.6%)
IRR 1.75 (1.29–2.39), p0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Erosion score>0 Erosion score≥2 Max diameter≥2.5 mm Erosion score>0 Erosion score≥2 Max diameter≥2.5 mm
25.7 (16.9 to 37.0) 8.6 (4.0 to 17.5) 20.0 (12.3 to 30.8) 4.3 (1.5 to 11.9) 47.1 (35.9 to 58.7) 14.3 (7.9 to 24.3) 24.3 (15.8 to 35.5) 11.4 (5.9 to 21.0) 40.0 (29.3 to 51.7) 5.7 (2.2 to 13.8) 47.1 (35.9 to 58.7) 2.9 (0.8 to 1.0) 37.1 (26.8 to 48.9) 7.1 (3.1 to 15.7) 61.4 (49.7 to 72.0) 18.6 (11.2 to 29.2) 68.6 (57.0 to 78.2) 35.7 (25.5 to 47.4) 91.4 (82.5 to 96.0) 50.0 (38.6 to 61.4) 68.6 (57.0 to 78.2) 81.4 (70.8 to 88.8) 41.4 (30.6 to 53.1) 58.6 (46.9 to 69.4)
10.7 (3.7 to 27.2) 3.6 (0.6 to 17.7) 10.7 (3.7 to 27.2) 0 (0 to 12.1) 42.9 (26.5 to 60.9) 3.6 (0.6 to 17.7) 10.7 (3.7 to 27.2) 3.6 (0.6 to 17.7) 35.7 (20.7 to 54.2) 0 (0 to 12.1) 39.3 (23.6 to 57.6) 3.6 (0.6 to 17.7) 14.3 (5.7 to 31.5) 3.6 (0.6 to 17.7) 46.4 (29.5 to 64.2) 7.1 (2.0 to 22.6) 53.5 (35.8 to 70.5) 17.9 (7.9 to 35.6) 89.3 (72.8 to 96.3) 25.0 (12.7 to 43.4) 57.1 (39.1 to 73.5) 75.0 (56.6 to 87.3) 17.8 (7.9 to 35.6) 50.0 (32.6 to 67.4)
87.9 (83.2 96.7 (93.6 86.7 (81.8 96.3 (93.0 87.1 (82.2 99.6 (97.7 96.7 (93.6 99.6 (97.8 94.6 (91.0 100 (98.4 70.0 (63.9 100 (98.4 89.6 (85.1 99.6 (97.7 69.6 (63.5 96.7 (93.6 85.4 (80.4 98.8 (96.4 32.9 (28.3 89.2 (84.6 75.8 (70.0 68.8 (62.6 97.9 (95.2 90.0 (85.6
84.4 (78.4 95.6 (91.5 82.2 (76.0 95.0 (90.8 83.3 (77.2 99.4 (96.9 95.6 (91.5 99.4 (96.9 92.8 (88.0 100 (97.9 66.7 (59.5 100 (97.9 86.1 (80.3 99.4 (96.9 62.8 (55.5 95.6 (91.5 81.7 (75.4 98.3 (95.2 21.7 (16.3 85.6 (79.7 68.3 (61.2 60.0 (52.7 97.2 (93.7 86.7 (80.9
to to to to to to to to to to to to to to to to to to to to to to to to
91.5) 98.3) 90.4) 98.0) 90.7) 99.9) 98.3) 99.9) 96.8) 100) 75.4) 100) 92.8) 99.9) 75.1) 98.3) 89.3) 99.6) 39.1) 92.5) 80.8) 74.3) 99.1) 93.2)
to to to to to to to to to to to to to to to to to to to to to to to to
89.0) 97.7) 87.1) 97.3) 88.1) 99.9) 97.7) 99.9) 95.7) 100) 73.1) 100) 90.4) 99.9) 69.5) 97.7) 86.6) 99.4) 28.2) 89.9) 74.7) 66.9) 98.8) 90.9)
*US/MCP2, 5/MTP5= distal ulna, 2nd and 5th MCP joints and 5th MTP joint all together. DU, distal ulna; MCP, metacarpophalangeal; MTP, metatarsophalangeal; PIP, proximal interphalangeal; RA, rheumatoid arthritis.
When looking at what size of erosion was predictive and specific for RA, ROC analysis (HC excluded) indicated that the diameter of the largest erosion in the distal ulna, 2nd MCP, 5th MCP and 5th MTP joints was predictive of RA (area under the ROC curve (95% CI) 0.78 (0.71 to 0.84), p
