Performance of the identified cut-offs at first follow-up or regular screening after initial detection (n=437; 412 benign nodules and 25 lung cancer nodules)
| All new solid nodules that persisted at first LDCT after detection | Subsequent LDCT within 120 days (short-term follow-up) | Subsequent LDCT after 120 days | |
| VDT ≤590 days | |||
| Sensitivity (95% CI) | 23/25, 92.0% (73.9 to 98.9) | 15/17, 88.2% (64.4 to 98.0) | 8/8, 100% (62.8 to 100) |
| Specificity (95% CI) | 360/412, 87.4% (83.8 to 90.3) | 137/178, 77.0% (70.2 to 82.6) | 223/234, 95.3% (91.7 to 97.4) |
| PPV (95% CI) | 23/75, 30.7% (21.3 to 41.9) | 15/56, 26.8% (17.5 to 41.0) | 8/19, 42.1% (23.1 to 63.8) |
| NPV (95% CI) | 360/362, 99.4% (97.9 to 100) | 137/139, 98.6% (94.6 to 99.9) | 223/223, 100% (98.0 to 100) |
| Volume ≥65 mm3 | |||
| Sensitivity (95% CI) | 24/25, 96.0% (78.9 to 100) | 16/17, 94.1% (71.1 to 100) | 8/8, 100% (62.8 to 100) |
| Specificity (95% CI) | 313/412, 76.0% (71.6 to 79.9) | 94/178, 52.8% (45.5 to 60.0) | 219/234, 93.6% (89.6 to 96.2) |
| PPV (95% CI) | 24/123, 19.5% (13.4 to 27.5) | 16/100, 16.0% (10.0 to 24.5) | 8/23, 34.8% (18.7 to 55.2) |
| NPV (95% CI) | 313/314, 99.7% (98.0 to 100) | 94/95, 98.9% (93.7 to 100) | 219/219, 100% (97.9 to 100) |
| VDT ≤590 days or volume ≥200 mm3 | |||
| Sensitivity (95% CI) | 25/25, 100.0% (84.2 to 100) | 17/17, 100.0% (78.4 to 100) | 8/8, 100% (62.8 to 100) |
| Specificity (95% CI) | 345/412, 83.7% (79.9 to 87.0) | 124/178, 69.7% (62.5 to 76.0) | 221/234, 94.4% (90.6 to 96.8) |
| PPV (95% CI) | 25/92, 27.2% (19.1 to 37.1) | 17/71, 24.6% (15.9 to 36.0) | 8/21, 38.1% (20.7 to 59.2) |
| NPV (95% CI) | 345/345, 100.0% (98.7 to 100) | 124/124, 100.0% (96.4 to 100) | 221/221, 100.0% (97.9 to 100) |
Exact volume measurement was not available or classification based on the radiologist’s size categorisation was unattainable for 17 benign nodules, and they were not included in the calculations.
LDCT, low-dose CT; NPV, negative predictive value; PPV, positive predictive value; VDT, volume doubling time.