Table 5 2 × 2 table of spirometry for diagnosing airway obstruction in patients with asthma in lung function laboratory (all patients included with differentiation between asthma and COPD)
| Â | asthma | no asthma | Â |
|---|---|---|---|
Spirometry + | 14 | 0 | Â |
Spirometry - | 76 | 129 | Â |
| Â | Â | Â | 219 |
Pretest probability of having asthma 41% | |||
Pretest probability of not having asthma 59% | |||
Sensitivity | 16% (95%CI 10–24) | ||
Specificity | 100% (95%CI 97–100) | ||
PPV | 100% (95%CI 79–100) | ||
NPV | 63% (95%CI 56–69) | ||