An independent inter- and intra-observer agreement assessment of the Eno classification of sacroiliac joint degeneration

Background Recently, a scoring system to grade sacroiliac joint (SIJ) degeneration using computed tomography (CT) scans was described. No independent evaluation has determined the inter- and intra-observer agreement using this scheme. Purpose To perform an independent inter- and intra-observer agreement assessment using the Eno classification and determining gas in the SIJ. Material and Methods We studied 64 patients aged >= 60 years who were evaluated with abdominal and pelvic computed tomography scans. Six physicians (three orthopaedic spine surgeons and three musculoskeletal radiologists) assessed axial images to grade SIJ degeneration into grade 0 (normal), grade 1 (mild degeneration), grade 2 (significant degeneration), and grade 3 (ankylosis). We also evaluated the agreement assessing the presence of gas in the SIJ. After a four-week interval, all cases were presented in a random sequence for repeat assessment. We determined the agreement using the kappa (kappa) or weighted kappa coefficient (w kappa). Results The inter-observer agreement was moderate (w kappa = 0.50 [0.44-0.56]), without differences among surgeons (w kappa = 0.53 [0.45-0.61]) and radiologists (w kappa = 0.49 [0.42-0.57]). The agreement evaluating the presence of gas was also moderate (kappa = 0.45 [0.35-0.54]), but radiologists obtained better agreement (kappa = 0.61 [0.48-0.72]) than surgeons (kappa = 0.29 [0.18-0.39]). The intra-observer agreement using the classification was substantial (w kappa = 0.79 [0.76-0.82]), without differences comparing surgeons (w kappa = 0.75 [0.70-0.80]) and radiologists (w kappa = 0.83 [0.79-0.87]). The intra-rater agreement evaluating gas was substantial (kappa = 0.77 [0.72-0.82]), without differences between surgeons (kappa = 0.71 [0.63-0.78]) and radiologists (kappa = 0.84 [0.78-0.90]). Conclusion Given the only moderate agreement obtained using the Eno classification, it does not seem adequate to be used in clinical practice or in research.

Automated summary

A recent study described a scoring system to grade sacroiliac joint (SIJ) degeneration using computed tomography (CT) scans, but independent evaluation showed only moderate agreement among observers using this scheme. The study aimed to assess inter- and intra-observer agreement independently using the Eno classification and determining gas in the SIJ. While substantial intra-observer agreement was found, the moderate inter-observer agreement suggests that the Eno classification may not be suitable for clinical practice or research.