Codes used in logistic regression analysis
| Study variable | Reference | Explanation |
| Advice to seek emergency care | All other care | 999 call or emergency care |
| Advice to seek care face to face | Self-care | Care face to face (including emergency care) |
| Gender | Male | Female |
| Main symptom (from International Classification of Primary Care-2) | Not digestive | Digestive |
| Relationship of patient to caller | Surrogate caller | Self |
| Other ethnic background | White or unknown | Other |
| Ethnicity known | Unknown | Known (white or other) |
| Call occurred on Sunday | All other days | Sunday |
| Call occurred on Monday | All other days | Monday |
| Call occurred on Tuesday | All other days | Tuesday |
| Call occurred on Wednesday | All other days | Wednesday |
| Call occurred on Thursday | All other days | Thursday |
| Call occurred on Friday | All other days | Friday |
| Call occurred on Saturday | all other days | Saturday |
| Deprivation fifth | Least deprived | Second least deprived (2=3rd most deprived; 3=2nd most deprived; 4 = most deprived) |