Influence of experience on intra- and inter-observer reproducibility of the Crowe, Hartofilakidis and modified Cochin classifications

IntroductionA previous study demonstrated that the reproducibility of the Crowe (Cr), the Hartofilakidis (Ha) and the modified Cochin (Co) classifications were comparable. However, there were differences with a trend that suggested the influence of experience. Therefore, we performed a prospective study to investigate whether experience influenced the reproducibility of the commonly used developmental dysplasia of the hip (DDH) classifications.HypothesisThe hypothesis was that the intra- and inter-observer reproducibility scores would be higher in the senior group than the junior group, and particularly for the modified Co classification.MethodsFour seniors and four residents classified 104 A/P pelvic radiographs (200 hips) two times using the Cr, Ha and Co classification systems.ResultsFor intra-observer reproducibility, the average weighted concordance coefficients [95% confidence intervals] were for the senior and the junior groups: 92.2 [88.6–95.7] and 92.6 [87.9–97.2] for Cr, 92.1 [88.7–94.6] and 92.0 [87.7–96.3] for Ha, 94.2 [91.8–96.6] and 94.1 [91.5–96.6] for Co. The average weighted Kappa (95% confidence intervals) were 0.8 [0.71–0.88] and 0.79 [0.68–0.89] for Cr, 0.77 [0.74–0.81] and 0.75 [0.62–0.88] for Ha, 0.82 [0.76–0.89] and 0.80 [0.74–0.87] for Co. The junior inter-observer reproducibility multi-rater Kappa (list A:list B) were 0.57:0.50 (Cr), 0.47:0.53 (Ha), 0.42:0.42 (Co). Senior multi-rater Kappa were 0.53:0.49 (Cr), 0.40:0.34 (Ha), 0.40:0.43 (Co).ConclusionsContrary to our hypothesis, the experience of the observer did not affect the intra- and inter-observer reproducibility of the three classification systems.