Methods A total of 66 children with CGHD from Sichuan area diagnosed in West China Second Hospital of Sichuan University from July 2014 to November 2019 were selected as research subjects and included into study group. And 67 children with normal height from Sichuan area who visited Department of Child Healthcare in cases collected hospital during the same period were selected as control and included into control group. Bone age of each child was examined by anteroposterior X-ray radiography of the left wrist joint. Bone ages of artificial TW2CHN-radial, ulnar, and short bones (RUS) and TW2CHN-carpal, TW2CHN-20, TW3-RUS and TW3-carpal (hereinafter referred to as 5 traditional bone ages) and their corresponding percentiles in children with the same gender and age were blindly evaluated by two physicians using TW2 Bone Age Scoring Method Southern Chinese Standard (hereinafter referred to as TW2CHN) and TW3 Bone Age Scoring Method Standard (hereinafter referred to as TW3). Meanwhile, the AI system was used to evaluate bone age and percentile of AI-TW2CHN-RUS, AI-TW2CHN-carpal, AI-TW2CHN-20, AI-TW3-RUS and AI-TW3-carpal (hereinafter referred to as 5 AI bone ages) of each subject by TW2CHN and TW3 methods respectively. Sensitivity, specificity, Youden index, accuracy, positive likelihood ratio, negative likelihood ratio, positive predictive value and negative predictive value of diagnosing CGHD children were calculated by using P50, P25, P10, and P3 values (collectively referred to as Pn values) of 5 traditional bone ages and 5 AI bone ages (hereinafter referred to as 10 bone ages) as critical values for diagnosis of CGHD in children. Kappa coefficient was used to evaluate the consistency of 5 traditional bone age percentile assessment results with the corresponding 5 AI bone age percentile assessment results, as well as the consistency of TW2CHN-RUS bone age percentile assessment results for 133 subjects by two physicians. The receiver operating characteristic (ROC) curves of 10 bone age percentile assessment results in diagnosis of CGHD were plotted and area under the curve (AUC) was calculated. Bone ages of TW2CHN and TW3 were compared by paired t test. The procedures followed in this study were in line with the requirements of newly revised World Medical Association Declaration of Helsinki in 2013. There were no significant differences in age, gender composition and other general clinical data between two groups (P>0.05).
Results ① CGHD diagnosis results of two groups by using Pn values of 10 bone ages as critical values for diagnosis of CGHD children showed that the diagnostic accuracy was the highest (85.0%) when bone age ≤P10 was used as the critical value for diagnosis of CGHD children except for TW3-RUS bone age. As for TW2CHN-RUS, TW2CHN-carpal, TW2CHN-20, TW3-carpal, AI-TW2CHN-RUS, AI-TW2CHN-carpal, AI-TW2CHN-20, AI-TW3-carpal, and AI-TW3-RUS bone ages, when bone age ≤P25 was taken as the critical value, the diagnostic accuracy of CGHD was the highest, which were 81.9%, 75.2%, 88.0%, 78.2%, 75.2%, 73.6%, 81.2%, 72.9%, 78.9%, respectively. ② Consistency test results showed that bone age percentiles of two groups evaluated by TW2CHN-RUS and AI-TW2CHN-RUS, TW2CHN-carpal and AI-TW2CHN-carpal, TW2CHN-20 and AI-TW2CHN-20, TW3-RUS and AI-TW3-RUS, TW3-carpal and AI-TW3-carpal were moderately consistent, and the Kappa values were 0.445, 0.578, 0.570, 0.446 and 0.430, respectively ( all P<0.001). ③Consistency test of TW2CHN-RUS bone age percentile evaluation results of two groups by two physicians showed that Kappa value was 0.790 (P<0.001), indicating a high consistency. ④ ROC curve analysis results of 10 bone age percentile for diagnosis of CGHD in two groups showed that AUC of TW2CHN-RUS, TW2CHN-carpal, TW2CHN-20, TW3-carpal, TW3-RUS, AI-TW2CHN-RUS, AI-TW2CHN-carpal, AI-TW2CHN-20, AI-TW3-carpal, AI-TW3-RUS bone ages for diagnosis of CGHD children were 0.932, 0.859, 0.915, 0.895, 0.844, 0.823, 0.805, 0.866, 0.860, 0.764 (all P<0.001). ⑤Bone ages of TW3-RUS, TW3-carpal, AI-TW3-RUS and AI-TW3-carpal in 133 subjects were significantly lower than those of TW2CHN-RUS, TW2CHN-carpal, AI-TW2CHN-RUS and AI-TW2CHN-carpal, respectively, and all differences were statistically significant (t=21.746, 25.287, 16.498, 9.290; P<0.001).