Patient characteristics
| Study 1 | Study 2 | |
| Subjects | 29 | 30 |
| Age years | 63.2±7.35 | 60.2±11.06 |
| Male:female | 4:25 | 6:24 |
| Race | ||
| Asian | 1 (3.4) | 1 (3.3) |
| Black or African-American | 0 (0) | 1 (3.3) |
| White | 28 (96.6) | 28 (93.3) |
| BMI kg·m−2 | 26.6±4.82 | 26.5±4.82 |
| Cough duration years | 15.4 (1.4–55.3) | 13.2 (1.9–42.8) |
| FEV1/FVC ratio % | 77.0 (67–102) | 82.0 (69–111) |
Data are presented as n, mean±sd, n (%) or median (range). BMI: body mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity.