Sensitivity, specificity, and Youden's index of screening methods for bronchial hyperresponsiveness (BHR) and clinical asthma: (1) respiratory symptoms reported in the parental screening questionnaire, (2) tests of BHR, and (3) a combination of symptoms and BHR tests
| Free running test | Methacholine inhalation challenge | Clinical asthma | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Screening method | Sensitivity | Specificity | Youden's index | Sensitivity | Specificity | Youden's index | Sensitivity | Specificity | Youden's index |
| The sensitivity and specificity estimates have been adjusted for the sampling scheme of the study.151–6Order of variable inclusions in the logistic regression analysis (see Methods and fig 2). *Wheezy chest apart from colds in the past 12 months—that is, symptom with the highest Youden's index v clinical asthma. | |||||||||
| (1) Symptoms only | |||||||||
| Wheezy chest apart from colds, in the past 12 months1 | 0.25 | 0.96 | 0.21 | 0.30 | 0.97 | 0.27 | 0.78 | 0.97 | 0.75 |
| Attacks of shortness of breath with wheezing in the past 12 months2 | 0.23 | 0.97 | 0.20 | 0.30 | 0.97 | 0.27 | 0.72 | 0.98 | 0.70 |
| Shortness of breath when playing outdoors or walking up the staircase in the past 12 months3 | 0.21 | 0.95 | 0.16 | 0.32 | 0.96 | 0.28 | 0.66 | 0.97 | 0.63 |
| Dry cough at night apart from a cold or chest infection in the past 12 months4 | 0.30 | 0.89 | 0.19 | 0.35 | 0.89 | 0.24 | 0.80 | 0.90 | 0.70 |
| Attacks of shortness of breath with wheezing ever | 0.55 | 0.87 | 0.42 | 0.59 | 0.87 | 0.46 | 0.78 | 0.87 | 0.65 |
| (2) BHR tests only | |||||||||
| Pathological free running test5 | 0.35 | 0.97 | 0.32 | ||||||
| Pathological methacholine inhalation challenge6 | 0.47 | 0.97 | 0.44 | ||||||
| (3) Symptoms and BHR tests | |||||||||
| Wheeze* and pathological free running test | 0.25 | 0.99 | 0.24 | ||||||
| Wheeze* and pathological methacholine inhalation challenge | 0.38 | 0.99 | 0.37 | ||||||