Change in self-reported cough between baseline and follow-up
| No cough at follow-up | Nonproductive cough at follow-up | Productive cough at follow-up | |
| No cough at baseline | 8487 (88.5) | 539 (5.6) | 561 (5.9) |
| Nonproductive cough at baseline | 484 (68.2) | 116 (16.3) | 110 (15.5) |
| Productive cough at baseline | 492 (51.5) | 109 (11.4) | 354 (37.1) |
Data are presented as n (% of baseline cough group).