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Table 2 Agreement as percent concordance among 10 possible reader pairs for each group of study subjects (kappa values for five readers jointly per cohort)

From: Does evaluation of the ligamentous compartment enhance diagnostic utility of sacroiliac joint MRI in axial spondyloarthritis?

Cohort A (n=89) B (n=88)
Group nr-axSpA AS NSBP HC nr-axSpA AS NSBP
Number of subjects 20 10 39 20 31 24 33
Percent concordance among 10 reader pairsa
Total (positive/negative)
 BME cart 88.0 (77.0/11.0) 88.0 (82.0/6.0) 78.5 (16.9/61.5) 85.0 (26.5/58.5) 78.1 (34.2/43.9) 78.3 (63.3/15.0) 86.7 (20.6/66.1)
 BME lig 78.0 (31.0/47.0) 92.0 (76.0/16.0) 93.8 (0.5/93.3) 89.0 (0.5/88.5) 87.7 (5.5/82.3) 61.7 (19.2/42.5) 97.0 (0.9/96.1)
 Fat cart 69.0 (31.5/37.5) 64.0 (48.0/16.0) 74.9 (16.7/58.2) 74.0 (5.0/69.0) 76.8 (32.3/44.5) 70.8 (64.6/6.3) 76.4 (10.6/65.8)
 Fat lig 77.0 (9.5/67.5) 64.0 (28.0/36.0) 82.1 (9.0/73.1) 86.0 (5.0/81.0) 77.4 (13.9/63.5) 60.8 (22.9/37.9) 89.1 (3.6/85.5)
Kappa value for five readers jointly (95 % CI)b
 BME cart 0.66 (0.56–0.75) 0.64 (0.53–0.72)
 BME lig 0.68 (0.55–-0.79) 0.37 (0.26–0.45)
 Fat cart 0.40 (0.32–0.49) 0.51 (0.42–0.60)
 Fat lig 0.36 (0.25–0.45) 0.39 (0.25–0.51)
  1. aPercent concordance among 10 possible reader pairs (100 % = 10 concordant reader pairs); Total = positive and negative concordance for presence/absence of BME or fat metaplasia in the cartilaginous and ligamentous compartment of the sacroiliac joints
  2. bWeighted Cohen’s kappa values for all five readers jointly
  3. AS Ankylosing spondylitis, BME Bone marrow edema, Cart Cartilaginous compartment of the sacroiliac joint, CI 95 % confidence interval, Fat Fat metaplasia, HC Healthy control, Lig Ligamentous compartment of the sacroiliac joint, nr-axSpA Nonradiographic axial spondyloarthritis, NSBP Nonspecific back pain, R Reader, RP Reader pair