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2 × 2 table of spirometry for diagnosing airway obstruction in patients with COPD (n = 208; asthma patients with FEV1 <80% of predicted in general practice and in lung function laboratory excluded)
| COPD | No COPD | ||
| Spirometry + | 44 | 26 | |
| Spirometry - | 4 | 134 | |
| 208 | |||
| Pretest probability of having COPD 23% | |||
| Pretest probability of not having COPD 77% | |||
| Sensitivity | 92% (95%CI 80–97) | ||
| Specificity | 84% (95%CI 77–89) | ||
| PPV | 63% (95%CI 51–73) | ||
| NPV | 97% (95%CI 93–99) | ||
