Definitions of heartburn frequency used in clinical trials
| Definitions | Examples of studies where definition was used |
|---|---|
| Rare: less than once a week | Schwizer32 |
| Moderate: twice a week | |
| Frequent: three to six times a week | |
| Daily | |
| Grade 0: absent | Vigneri20 |
| Grade 1: less than 2 days a week | |
| Grade 2: 2–4 days a week | |
| Grade 3: more than 4 days a week | |
| No of hours during the last 24 hour period when experiencing heartburn: | Johnsson18 |
| None | |
| <1 h | |
| 1–6 h | |
| >6 h | |
| No of days with heartburn in the last 7 days (0–7) | Venables7 |
| No of days with heartburn episodes during the last 7 days: | Venables26 |
| None | |
| 1 day | |
| 2–4 days | |
| 5–6 days | |
| 7 days | |
| Visual analogue scale 0–100 mm | Galmiche39 |