Table 2.
Summary of performance metrics of predictive models for Hologic BMD.
| Patient strata | Number of ROIs | Predicted vs. measured mean BMD (sd, g/cm2); p** | Correlation coefficient | Linear regression R2, RMSE | Calibration slop, CITL | Bland-Altman bias (g/cm2; sd) |
|---|---|---|---|---|---|---|
| The hip testing set (Hologic) | ||||||
| Overall | 5164 | 0.692 (0.144) vs. 0.689 (0.156); p < 0.001 | 0.92 | 0.84, 0.062 | 0.982, −0.003 | −0.003 (0.062) |
| Female | 3997 | 0.668 (0.137) vs. 0.661 (0.144); p < 0.001 | 0.91 | 0.83, 0.056 | 0.961, −0.007 | −0.007 (0.059) |
| Male | 1167 | 0.774 (0.137) vs. 0.782 (0.151); p < 0.001 | 0.89 | 0.80, 0.062 | 0.985, 0.008 | 0.008 (0.068) |
| 40–59 years | 712 | 0.796 (0.132) vs. 0.790 (0.140); p = 0.010 | 0.91 | 0.82, 0.056 | 0.987, −0.006 | −0.006 (0.061) |
| 60–74 years | 1817 | 0.722 (0.132) vs. 0.717 (0.141); p < 0.001 | 0.90 | 0.82, 0.057 | 0.963, −0.005 | −0.005 (0.061) |
| 75–90 years | 2635 | 0.644 (0.135) vs. 0.642 (0.148); p = 0.175 | 0.91 | 0.82, 0.057 | 0.998, −0.002 | −0.002 (0.062) |
| The spine testing set (Hologic)* | ||||||
| Overall | 57,662 | 0.837 (0.172) vs. 0.839 (0.186); p < 0.001 | 0.90 | 0.81, 0.081 | 0.978, 0.003 | 0.003 (0.081) |
| Female | 46,349 | 0.813 (0.162) vs. 0.813 (0.176); p < 0.001 | 0.89 | 0.80, 0.079 | 0.969, 0.000 | 0.000 (0.079) |
| Male | 11,313 | 0.931 (0.177) vs. 0.945 (0.191); p = 0.94 | 0.89 | 0.79, 0.088 | 0.958, 0.014 | 0.014 (0.088) |
| 40–59 years | 14,501 | 0.912 (0.160) vs. 0.909 (0.174); p < 0.001 | 0.90 | 0.80, 0.077 | 0.973, −0.003 | −0.003 (0.081) |
| 60–74 years | 26,935 | 0.827 (0.166) vs. 0.828 (0.181); p = 0.003 | 0.90 | 0.80, 0.079 | 0.978, 0.001 | 0.001 (0.079) |
| 75–90 years | 16,226 | 0.784 (0.166) vs. 0.795 (0.188); p < 0.001 | 0.88 | 0.79, 0.086 | 1.004, 0.011 | 0.011 (0.086) |
| L1 | 12,731 | 0.742 (0.150) vs. 0.747 (0.167); p < 0.001 | 0.87 | 0.76, 0.081 | 0.968, 0.006 | 0.006 (0.082) |
| L2 | 15,809 | 0.816 (0.160) vs. 0.821 (0.177); p < 0.001 | 0.90 | 0.81, 0.078 | 0.993, 0.006 | 0.006 (0.078) |
| L3 | 15,679 | 0.873 (0.163) vs. 0.873 (0.181); p = 0.22 | 0.90 | 0.80, 0.080 | 0.993, 0.001 | 0.001 (0.080) |
| L4 | 13,443 | 0.909 (0.167) vs. 0.907 (0.182); p = 0.01 | 0.88 | 0.78, 0.084 | 0.966, −0.002 | −0.002 (0.085) |
*Calculated per eligible vertebrae.
**Means were compared using student t-test and medians were compared using Wilcoxon rank-sum test. Two-sided p values were reported.