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Table 3 Inter-rater reliability coefficients and percent agreement with probabilistic benchmarking to the Landis and Koch scale in classification of MRI-findings at disc level

From: Degenerative findings in lumbar spine MRI: an inter-rater reliability study involving three raters

Diagnostic finding
N = 177 disc levels
Reliability
Rater 1 vs. 2
Reliability
Rater 1 vs. 3
Reliability
Rater 2 vs. 3
AllLandis and
Koch scale
 95% C.I.95% C.I.95% C.I. Probabilistic benchmark
Spondylolisthesis
 Conger’s K0.24 [−0.16:0.64]0.36 [−0.01:0.72]0.36 [− 0.01:0.72]0.33Slight
 Gwet’s AC20.998 [0.997:1.000]0.998 [0.996:0.999]0.998 [0.996:0.999]0.99Almost perfect
 %-agreement0.998 [0.997:1.000]0.998 [0.996:0.999]0.998 [0.996:0.999]0.99Almost perfect
Disc degeneration
 Conger’s K0.60 [0.51:0.70]0.67 [0.58:0.76]0.76 [0.69:0.82]0.68Moderate
 Gwet’s AC20.90 [0.87:0.94]0.89 [0.85:0.93]0.91 [0.88:0.95]0.90Substantial
 %-agreement0.95 [0.93:0.96]0.94 [0.93:0.96]0.96 [0.95:0.97]0.95Substantial
Nerve compromise
 Conger’s K0.55 [0.38:0.71]0.56 [0.39:0.72]0.52 [0.34:0.70]0.54Fair
 Gwet’s AC20.96 [0.93:0.98]0.93 [0.90:0.96]0.92 [0.89:0.96]0.93Substantial
 %-agreement0.96 [0.95:0.98]0.95 [0.93–0.97]0.94 [0.92:0.97]0.95Substantial
Spinal stenosis
 Conger’s K0.19 [0.08:0.29]0.33 [0.22:0.45]0.43 [0.34:0.53]0.33Fair
 Gwet’s AC20.98 [0.97:0.98]0.98 [0.98:0.99]0.98 [0.97:0.98]0.98Almost perfect
 %-agreement0.98 [0.98:0.99]0.99 [0.98:0.99]0.98 [0.98:0.99]0.98Almost perfect
Facet degeneration
 Conger’s K0.27 [0.16:0.38]0.32 [0.21:0.42]0.35 [0.25:0.46]0.32Slight
 Gwet’s AC20.79 [0.74:0.84]0.79 [0.74:0.84]0.76 [0.71:0.82]0.78Moderate
 %-agreement0.88 [0.86:0.90]0.89 [0.86–0.91]0.87 [0.85:0.90]0.88Moderate
Scoliosis
 Cohen’s K0.49 [0.06:0.92]0.59 [0.22:0.96]0.75 [0.40:1.00]0.61Fair
 Gwet’s AC10.98 [0.96:1.00]0.98 [0.96:1.00]0.99 [0.97:1.00]0.98Almost perfect
 %-agreement0.98 [0.96:1.00]0.98 [0.96:1.00]0.99 [0.97:1.00]0.98Almost perfect
Annular Fissure
 Cohen’s K0.50 [0.32:0.68]0.45 [0.26:0.65]0.61 [0.45:0.77]0.53Moderate
 Gwet’s AC10.87 [0.82:0.93]0.88 [0.82:0.93]0.88 [0.83:0.93]0.88Almost perfect
 %-agreement0.88 [0.83:0.93]0.88 [0.83:0.93]0.89 [0.84:0.93]0.88Almost perfect
Disc contour
 Cohen’s K0.36 [0.25:0.48]0.27 [0.17:0.38]0.39 [0.29:0.49]0.34Fair
 Gwet’s AC10.73 [0.65:0.80]0.59 [0.50:0.68]0.62 [0.53:0.70]0.64Moderate
 %-agreement0.75 [0.69:0.82]0.64 [0.57:0.71]0.67 [0.60:0.74]0.69Substantial
  1. Inter-rater reliability using Gwet’s AC1 (binominal/nominal data) and AC2 (ordinal data) and percent agreement are presented
  2. For comparison Cohen’s K (binominal/nominal data) and Conger’s K (ordinal data) also presented
  3. Numbers in parentheses are 95% confidence intervals [95% CI]