Table 4 2 × 2 table of spirometry for diagnosing airway obstruction in patients with asthma in general practice (n = 168; patients with COPD excluded)
| Â | asthma | no asthma | Â |
|---|---|---|---|
Spirometry + | 26 | 8 | Â |
Spirometry - | 63 | 71 | Â |
| Â | Â | Â | 168 |
Pretest probability of having asthma 41% | |||
Pretest probability of not having asthma 59% | |||
Sensitivity | 29% (95%CI 21–39) | ||
Specificity | 90% (95%CI 81–95) | ||
PPV | 77% (95%CI 60–88) | ||
NPV | 53% (95%CI 45–61) | ||