Table 2. Characteristics of included studies.
| Study characteristics | Studies* (number) |
|---|---|
| Total | 102 |
| Year of publication | |
| Before 2000 | 17 |
| 2000–2005 | 15 |
| 2006–2010 | 38 |
| After 2010 | 32 |
| Level of analysis | |
| Individual | 59 |
| Area | 43 |
| Region | |
| Asia | 3 |
| Europe | 49 |
| North America | 34 |
| Oceania | 16 |
| Sample size | |
| <200 | 3 |
| 200–1000 | 25 |
| 1001–5000 | 15 |
| 5001–10000 | 9 |
| 10001–100000 | 5 |
| >100000 | 45 |
| Age category | |
| Children (<18 years old) | 27 |
| Adults | 8 |
| Mixed | 61 |
| Not stated | 6 |
| Gastrointestinal infection outcome | |
| Acute GI infection (syndromic) | 41 |
| Campylobacteriosis | 20 |
| Cryptosporidiosis | 4 |
| Giardiasis | 3 |
| Hepatitis A | 3 |
| Listeriosis | 1 |
| Norovirus | 1 |
| Rotavirus | 3 |
| Salmonellosis | 8 |
| Shigellosis | 3 |
| Shiga toxin-producing E. coli infection | 4 |
| Yersinia enterocolitica | 1 |
| Multiple pathogens | 10 |
| Gastrointestinal infection measure | |
| Population-based survey | 30 |
| General practice (GP) presentation | 5 |
| Hospital admission | 13 |
| Laboratory records | 52 |
| Multiple measures | 2 |
| Socioeconomic status measure | |
| Deprivation | 17 |
| Education | 22 |
| Employment | 7 |
| Income | 10 |
| Occupation | 8 |
| Social class | 10 |
| Multiple measures | 28 |
| Study design | |
| Case-control | 25 |
| Cohort | 16 |
| Cross-sectional | 18 |
| Ecological | 43 |
| Quality | |
| High | 19 |
| Medium | 27 |
| Low | 56 |
*See S1 File for full overview of included studies.