Table 1.
Patient characteristics of the study population.
| Hip testing set | Spine testing set | |||||
|---|---|---|---|---|---|---|
| Hologic training | Hologic testing | p*** | Hologic training | Hologic testing | p*** | |
| Number | 5633 | 5164 | 7307 | 18,175 | ||
| Female, n (%) | 4380 (77.8) | 3997 (77.4) | 0.66 | 5815 (79.6) | 14,469 (79.6) | 0.96 |
| Mean age (sd), years | 72.8 (11.0) | 72.2 (11.2) | 0.004 | 67.2 (12.5) | 67.1 (10.6) | <0.001 |
| Median time (IQR) between DXA and radiographs | 31 (8, 81) | 29 (8, 77) | 0.13 | 24 (22, 27) | 16 (5, 48) | <0.001 |
| Mean BMI (sd), kg/m2* | 23.8 (3.9) | 23.9 (3.9) | 0.08 | 24.6 (3.8) | 24.5 (3.8) | 0.06 |
| Mean BMD (sd) g/cm2 | 0.678 (0.159) | 0.689 (0.156) | <0.001 | 0.740 (0.173)** | 0.762 (0.176)** | <0.001 |
| Median T-score (IQR) | −1.6 (−2.4, −0.6) | −1.5 (−2.3, −0.6) | <0.001 | −2.3 (−3.3, −1.3)** | −2.2 (−3.1, −1.1)** | <0.001 |
| Osteoporosis, n (%) | 1356 (24.1) | 1110 (21.5) | <0.001 | 3291 (45.0)** | 7860 (43.3)** | 0.009 |
*BMI was not available in 330/66 patients in the hip training/testing sets and 223 and 623 in the spine training/testing sets.
**Calculated based on vertebrae with the lowest BMD.
***Categorical variables (gender and osteoporosis) were compared using Chi-square test. Means were compared using student t-test and medians were compared using Wilcoxon rank-sum test. Two-sided p values were reported.