| Heartburn n (%) | Regurgitation n (%) | p value | |
| Position | <0.001 | ||
| Upright | 54 (71.1) | 236 (95.9) | |
| Supine | 22 (28.9) | 10 (4.1) | |
| Composition | 0.009 | ||
| Liquid | 53 (69.7) | 130 (52.8) | |
| Mixed liquid–gas | 23 (30.3) | 116 (47.2) | |
| Reflux | 0.027 | ||
| Acid | 24 (31.6) | 48 (19.5) | |
| Weakly acidic/weakly alkaline | 52 (68.4) | 198 (80.5) | |
| Nadir pH* | 4.8 (3.7–5.5) | 5.5 (4.2–6.1) | <0.001 |
| Acid clearance time (s)* | 12 (0–34.5) | 17 (0–30) | 0.872 |
| Acid burden (s)* | 0 (0–128.9) | 0 (0–0) | <0.001 |
| Preceding acid reflux (1 h) | <0.001 | ||
| Yes | 37 (48.7) | 67 (27.2) | |
| No | 39 (51.3) | 179 (72.8) | |
| Number of preceding acid refluxes* | 0 (0–5) | 0 (0–1) | <0.001 |
| Preceding weakly acidic reflux (1 h) | 0.860 | ||
| Yes | 70 (92.1) | 225 (91.5) | |
| No | 6 (7.9) | 21 (8.5) | |
| Number of preceding weakly acidic refluxes* | 4 (3–8) | 5 (2–10) | 0.732 |
| Reflux bolus clearance time (s)* | 16.3 (7.3–60.9) | 10.3 (5.7–20.9) | <0.001 |
| Bolus burden (s)* | 157.9 (51.8–445.2) | 117.6 (47.5–252) | 0.034 |
| Proximal reflux events | 0.614 | ||
| Yes | 54 (71.1) | 182 (74.0) | |
| No | 22 (28.9) | 64 (26.0) |
*Median (interquartile range).