| Age years | Criterion | Fulfilled criteria (feasibility)# | Visually acceptable¶ | Visually unacceptable+ | |||
| Fulfilled criteria (sensitivity) | Did not fulfil criteria | Fulfilled criteria | Did not fulfil criteria (specificity) | ||||
| BEV | <6 | 12.5% FVC or 80 mL | 628/637 (98.6) | 342/342 (100.0) | 0/342 (0.0) | 286/295 (96.9) | 9/295 (3.1) |
| ≥6 | 5% FVC or 150 mL | 2417/2496 (96.8) | 1916/1920) (99.8) | 4/1920 (0.2) | 501/576 (87.0) | 75/576 (13.0) | |
| All | 3045/3133 (97.2) | 2258/2262 (99.8) | 4/2262 (0.2) | 787/871 (90.4) | 84/871 (9.6) | ||
| Repeatability difference FEV1 and FVC | <6 | 10% or 0.1 L | 480/637 (75.4) | 298/342 (87.1) | 44/342 (12.9) | 182/295 (61.7) | 113/295 (38.3) |
| ≥6 | 0.15 L | 2160/2496 (86.5) | 1731/1920 (90.2) | 189/1920 (9.8) | 429/576 (74.5) | 147/576 (25.5) | |
| All | 2640/3133 (84.3) | 2029/2262 (89.7) | 233/2262 (10.3) | 611/871 (70.1) | 260/871 (29.9) | ||
| FET | <6 | 637/637 (100) | 342/342 (100.0) | 0/342 (0.0) | 295/295 (100.0) | 0/295 (0.0) | |
| 6–10 | 3 s | 606/865 (70.1) | 479/617 (77.6) | 138/617 (22.4) | 127/248 (51.2) | 121/248 (48.8) | |
| 10–19 | 6 s | 258/1631 (15.8) | 240/1303 (18.4) | 1063/1303 (81.6) | 18/328 (5.5) | 310/328 (94.5) | |
| All | 1501/3133 (47.9) | 1061/2262 (46.9) | 1201/2262 (53.1) | 440/871 (50.5) | 431/871 (49.5) | ||
| Combination of repeatability and BEV | <6 | 476/637 (74.7) | 298/342 (87.1) | 44/342 (12.9) | 178/295 (60.3) | 117/295 (39.7) | |
| ≥6 | 2111/2496 (84.6) | 1728/1920 (90.0) | 192/1920 (10.0) | 383/576 (66.5) | 193/576 (33.5) | ||
| All | 2587/3133 (82.6) | 2026/2262 (89.6) | 236/2262 (10.4) | 561/871 (64.4) | 310/871 (35.6) | ||
| Combination of repeatability, BEV and FET | <6 | 476/637 (74.7) | 298/342 (87.1) | 44/342 (12.9) | 178/295 (60.3) | 117/295 (39.7) | |
| ≥6 | 767/2496 (30.7) | 659/1920 (34.3) | 1261/1920 (65.7) | 108/576 (18.8) | 468/576 (81.2) | ||
| All | 1243/3133 (39.7) | 957/2262 (42.3) | 1305/2262 (57.7) | 286/871 (32.8) | 585/871 (67.2) | ||
Data are presented as n/N (%). BEV: back-extrapolated volume; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; FET: forced expiratory time. #: n=3133 healthy children from the LUNOKID study; ¶: n=2262; +: n=871.