Table 5.

Performance of SVM, PCA and CT attenuation threshold models in the test dataset.

Osteoporosis	Sensitivity	Specificity	AUC	Accuracy	Positive Predictive Value (PPV)	Negative Predictive Value (NPV)
CT attenuation threshold of 143.243 HU at the calcaneus	0.00	1.00	0.356	0.750	-	0.750
CT attenuation threshold of 260.755 HU at the medial cuneiform	0.667	0.578	0.622	0.600	0.345	0.839
SVM with RBF kernel	0.867	0.733	0.867	0.767	0.520	0.943
PCA model	0.533	0.933	0.733	0.833	0.727	0.857
Osteopenia/osteoporosis	Sensitivity	Specificity	AUC	Accuracy	Positive Predictive Value (PPV)	Negative Predictive Value (NPV)
CT attenuation threshold of 141.054 HU at the calcaneus	0.630	0.786	0.708	0.750	0.474	0.878
CT attenuation threshold of 327.331 HU at the medial cuneiform	0.00	1.00	0.318	0.767	-	0.767
SVM with RBF kernel	0.696	0.857	0.783	0.817	0.588	0.907
PCA model	0.913	0.357	0.635	0.483	0.302	0.941
Femoral neck BMD T-score ≤ -2.5	Sensitivity	Specificity	AUC	Accuracy	Positive Predictive Value (PPV)	Negative Predictive Value (NPV)
CT attenuation threshold of 116.188 HU at the calcaneus	0.625	0.731	0.678	0.717	0.263	0.927
CT attenuation threshold of 257.709 HU at the medial cuneiform	0.625	0.538	0.582	0.550	0.172	0.903
SVM with RBF kernel	0.875	0.635	0.750	0.667	0.269	0.971
PCA model	0.125	0.923	0.524	0.817	0.200	0.873
Femoral neck BMD T-score < -1	Sensitivity	Specificity	AUC	Accuracy	Positive Predictive Value (PPV)	Negative Predictive Value (NPV)
CT attenuation threshold of 122.043 HU at the calcaneus	0.00	1.00	0.382	0.400	-	0.400
CT attenuation threshold of 245.128 HU at the medial cuneiform	0.00	1.00	0.424	0.400	-	0.400
SVM with RBF kernel	0.972	0.500	0.766	0.783	0.745	0.923
PCA model	0.889	0.292	0.590	0.650	0.653	0.636

BMD, bone mineral density; SVM, support vector machine; RBF, radial basis function; PCA, principal components analysis.