Baseline demographics and clinical characteristics
| Omeprazole (n=23) | Placebo (n=22) | |
| Female | 4 (17%) | 6 (27%) |
| Male | 19 (83%) | 16 (73%) |
| Age (years) | 71.3 (6.7) | 71 (7.3) |
| Smoking history | ||
| Never smoked | 5 (22%) | 5 (23%) |
| Ex-smoker | 18 (78%) | 16 (73%) |
| Current smoker | 0 (0%) | 1 (5%) |
| Pack years* | 13.0 (7.5–20.0) | 15.0 (7.0–36.0) |
| BMI (kg/m2) | 28.9 (3.8) | 29.6 (6.0) |
| Concomitant pirfenidone | 8 | 10 |
| Concomitant nintedanib | 0 | 2 |
| Concomitant prednisolone† | 0 | 4 |
| Respiratory rate (breaths/min) | 21.5 (3.5) | 22.4 (3.8) |
| FEV1 (% predicted) | 76.9 (15.4) | 78.4 (18.4) |
| FVC (% predicted) | 73.1 (17.1) | 77.9 (17.6) |
| Kco (% predicted) | 87.3 (20.9) | 83.0 (22.0) |
| TLco (% predicted) | 49.5 (15.7) | 48.4 (16.0) |
| 6MWD (m) | 416.5 (296.5–485.0) | 372.5 (307.6–450.0) |
| DeMRQ | 0.9 (0.8) | 1.5 (1.4) |
| GIQLI | 106.3 (17.9) | 104.8 (17.8) |
| LCQ | 15.1 (3.2) | 15.4 (3.2) |
| RSI | 14.3 (9.6) | 17.1 (9.0) |
| Coughs/hour—24 hours | 9.6 (4.2–18.3) | 8.9 (6.8–12.8) |
| Coughs/hour—daytime | 13.4 (6.0–24.3) | 11.6 (8.5–17.4) |
| Coughs/hour—night-time | 2.1 (0.5–6.9) | 2.6 (0.8–9.0) |
Data are presented as n (%), mean (standard deviation (SD)) or median (IQR).
*Pack years are shown for participants who were current or ex-smokers and for whom the number of pack years was known (n=16 in the omeprazole group and n=15 in the placebo group).
†The doses received by the 4 patients were 4 mg, 6 mg, 10 mg or 15 mg per day. 6MWD was performed in 21 of the 22 participants in the placebo group and in all 23 participants in the omeprazole group.
6MWD, 6 min walk distance; BMI, body mass index; DeMRQ, De Meester reflux-related symptoms questionnaire; GIQLI, Gastrointestinal Quality of Life Index; LCQ, Leicester Cough Questionnaire; RSI, Reflux Symptoms Index; TLco, transfer factor for carbon monoxide