Outcomes After Initial Negative Exam
| Group | Initial exam negative | Repeat exam within 1 wk | P | False-negative result or follow-up beyond 90 d | False-negative result | P |
| VQ | ||||||
| Asthma | 2,667 | 51 (1.9%) | 0.547 | 2,463 | 10 (0.4%) | 0.015 |
| Nonasthma | 7,746 | 163 (2.1%) | 6,273 | 57 (0.9%) | ||
| CTPA | ||||||
| Asthma | 1,373 | 8 (0.6%) | 0.796 | 1,190 | 23 (1.9%) | 0.347 |
| Nonasthma | 5,118 | 33 (0.6%) | 3,838 | 59 (1.5%) |