Table 2.
Diagnostic Test Characteristics of the Decision Trees
| Variable | Derivation Cohort | Test Cohort | Calibration Cohort (Combined Derivation and Test Cohorts) |
Validation Cohort |
|---|---|---|---|---|
| No. of subjects | 341 | 331 | 672 | 209 |
| No. of true positives | 102 | 87 | 182 | 75 |
| No. of true negatives | 131 | 114 | 291 | 73 |
| No. of false positives | 101 | 118 | 173 | 48 |
| No. of false negatives | 7 | 12 | 26 | 13 |
| Sensitivity | 94% (87–97)a | 88% (79–93) | 88% (82–92) | 85% (76–92) |
| Specificity | 56% (50–63) | 49% (43–56) | 63% (58–67) | 60% (51–69) |
| Positive predictive value | 50% (43–57) | 42% (36–50) | 51% (46–57) | 61% (52–70) |
| Negative predictive value | 95% (89–98) | 90% (84–95) | 92% (88–94) | 85% (75–91) |
| Positive likelihood ratio | 2.1 (1.8–2.5) | 1.7 (1.5–2.0) | 2.3 (2.1–2.7) | 2.1 (1.7–2.7) |
| Negative likelihood ratio | 0.1 (0.06–0.2) | 0.2 (0.1–0.4) | 0.2 (0.1–0.3) | 0.2 (0.1–0.4) |
| Area under the curve | 0.834 (0.792–0.875) | 0.720 (0.661–0.780) | 0.793 (0.758–0.823) | 0.726 (0.660–0.792) |
a
Numbers in parentheses represent 95% CIs.