We also performed ROC analysis (Figure 1). We compared CRP and IMA ROC curves for each Wagner classification. In addition, we estimated the cut-off value, AUC, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CPR and IMA for each one Wagner classification (Table 4). When we investigated the ROC curves for Wagner grade 1 and 2, we found relative lower AUC, sensitivity and specificity in terms of CRP and IMA. For Wagner grade 1 and 3, the AUC, sensitivity and specificity values of CPR were higher than those of IMA. When ROC curves of Wagner grade 1-4 and 1-5 classifications were examined, it can be said that both CRP and IMA had relatively high AUC, sensitivity and specificity values, but CPR values were higher than IMA. Similar to the Wagner grade 1-3 comparison ROC curve, relatively low AUC, sensitivity and specificity values were obtained in the Wagner grade 2-3 ROC curve, in terms of CPR and IMA. We found relatively high AUC, sensitivity and specificity values for both CRP and IMA in Wagner grade 2-4 and 2-5 comparison ROC curves. In addition, for Wagner grade 3-4 and 3-5 comparison ROC curves, we found relatively high AUC, sensitivity and specificity values for both CRP and IMA. Unlike other Wagner grade ROC comparisons, the AUC, sensitivity and specificity values of IMA for Wagner grade 4-5 were higher than those of CRP. When the patient group was classified according to the presence of osteomyelitis and the ROC curves were examined, it was observed that the AUC, sensitivity and specificity values of CRP were higher than those of IMA. We summarise all AUC, sensitivity, specificity, PPV and NPV data in Table 4.
Table 4: Screening performance characteristics of CRP and IMA in predicting Wagner classification.