Table 3.
Diagnostic values for individual tests in 477 children
| Sensitivity | Specificity | Positive predictive value | Negative predictive value | |
|---|---|---|---|---|
| FEV1:FVC (n=477; AUROC=0·701) | ||||
| <70% | 2/74 (3%) | 398/403 (99%) | 2/7 (29%) | 398/470 (85%) |
| <75% | 8/74 (11%) | 391/403 (97%) | 8/20 (40%) | 391/457 (86%) |
| <80% | 20/74 (27%) | 368/403 (91%) | 20/55 (36%) | 368/422 (87%) |
| LLN | 11/74 (15%) | 391/403 (97%) | 11/23 (48%) | 391/454 (86%) |
| <83·8%* | 40/74 (54%) | 328/403 (81%) | 40/115 (35%) | 328/362 (91%) |
| Bronchodilator reversibility (n=473; AUROC=0·636) | ||||
| ≥12% | 12/74 (16%) | 373/399 (93%) | 12/38 (32%) | 373/435 (86%) |
| ≥15% | 7/74 (9%) | 380/399 (95%) | 7/26 (27%) | 380/447 (85%) |
| ≥3·48%* | 57/74 (77%) | 181/399 (45%) | 57/275 (21%) | 181/198 (91%) |
| FeNO (n=370; AUROC=0·711) | ||||
| ≥35 ppb | 29/56 (52%) | 260/314 (83%) | 29/83 (35%) | 260/287 (91%) |
| ≥40 ppb | 26/56 (46%) | 272/314 (87%) | 26/68 (38%) | 272/302 (90%) |
| ≥24 ppb* | 35/56 (63%) | 228/314 (73%) | 35/121 (29%) | 228/249 (92%) |
| FEV1 % predicted†(n=477; AUROC=0·623) | ||||
| <80% | 16/74 (22%) | 384/403 (95%) | 16/35 (46%) | 384/442 (87%) |
| <91·045%* | 32/74 (43%) | 312/403 (77%) | 32/123 (26%) | 312/354 (88%) |
Data include children with asthma (n=74) and non-asthmatic controls (n=403) who had spirometry. Children with possible asthma were excluded. FEV1=forced expiratory volume in 1 s. FVC=forced vital capacity. AUROC=area under the receiver-operating characteristic curve. LLN=lower limit of normal. FeNO=fractional exhaled nitric oxide. ppb=parts per billion.
*
The values denote the best cutoffs according to Youden's J statistic (sensitivity + specificity − 1) for this population.
†
FEV1 % predicted does not form part of the diagnostic algorithm but has been included for completeness.