Table 2. Characteristics of studies included in the systematic review (n = 135).
| Study characteristics | Number of studies | Proportion (%) |
|---|---|---|
| Publication year | ||
| 2021 | 17 | 10.9 |
| 2020 | 26 | 16.67 |
| 2019 | 32 | 20.51 |
| 2018 | 25 | 16.03 |
| 2017 | 8 | 5.13 |
| 2016 | 9 | 5.77 |
| 2015 | 9 | 5.77 |
| 2014 | 8 | 5.13 |
| 2013 | 5 | 3.21 |
| 2012 | 4 | 2.56 |
| 2011 | 5 | 3.21 |
| 2010 and before | 8 | 5.13 |
| Language | ||
| English | 154 | 98.72 |
| 2 | 1.28 | |
| Country | ||
| US | 27 | 17.31 |
| Uruguay | 19 | 12.18 |
| France | 16 | 10.26 |
| Canada | 11 | 7.05 |
| Australia | 10 | 6.41 |
| UK | 9 | 5.77 |
| New Zealand | 7 | 4.49 |
| Chile | 7 | 4.49 |
| Brazil | 7 | 4.49 |
| Germany | 6 | 3.85 |
| Ecuador | 5 | 3.21 |
| Switzerland | 3 | 1.92 |
| Mexico | 3 | 1.92 |
| Other | 19 | 16.67 |
| Region | ||
| Europe | 49 | 31.41 |
| Latin America | 43 | 27.56 |
| North America | 38 | 24.36 |
| Oceania | 17 | 10.9 |
| Asia | 4 | 2.56 |
| Africa | 1 | 0.64 |
| Multiple | 4 | 2.56 |
| Setting | ||
| Laboratory | 148 | 94.87 |
| Real-world | 8 | 5.13 |
| Out-of-home sectors* | 4 | 2.56 |
| Retailer outlets | 4 | 2.56 |
| Study design | ||
| RCT | 101 | 64.74 |
| Quasi-experimental studies and cross-sectional survey | 55 | 35.26 |
| Intervention label | ||
| TLS | 97 | 62.18 |
| NW | 62 | 39.74 |
| NS | 35 | 22.44 |
| HW | 27 | 17.31 |
| Control condition | ||
| No label | 125 | 80.13 |
| NFt | 12 | 7.69 |
| Compared against each other colour-coded or warning labels | 19 | 12.18 |
| Types of foods and drinks tested | ||
| Multiple | 87 | 55.77 |
| Single | 62 | 39.74 |
| Not stated | 7 | 17.31 |
| Research data | ||
| Individual data | 152 | 97.44 |
| Sales data | 4 | 2.56 |
| Age group | ||
| Primarily adults | 134 | 88.16 |
| Primarily children or adolescents | 5 | 3.29 |
| Mixed population made up of adults, children, and adolescents | 5 | 3.29 |
| Not stated | 8 | 5.26 |
| Sex | ||
| Mixed | 85 | 55.92 |
| Mostly female | 60 | 39.47 |
| Mostly male | 1 | 0.66 |
| Not stated | 6 | 3.95 |
| Education # | ||
| High | 47 | 30.92 |
| Low | 45 | 29.61 |
| Not stated | 60 | 39.47 |
| Individual/Familial income | ||
| High | 1 | 0.66 |
| Low | 6 | 3.95 |
| Mixed | 48 | 31.58 |
| Not stated | 97 | 63.82 |
| Occupation | ||
| Undergraduate students | 6 | 3.95 |
| Primary school students | 1 | 0.66 |
| Mixed | 11 | 7.24 |
| Not stated | 134 | 88.16 |
| Presence of NFt along with intervention label | ||
| Yes | 34 | 21.79 |
| No | 122 | 78.21 |
| Risk of bias | ||
| High | 107 | 68.59 |
| Moderate/Some concerns | 35 | 22.44 |
| Low | 14 | 8.97 |
*Out-of-home sector includes any outlet where food or drink is prepared for immediate consumption by consumers, such as restaurants, cafes, and takeaways.
#Education was classified as “high” if >50% of study population completed university or college education, otherwise classified into “low.”
HW, health warning; NFt, Nutrition Facts table; NS, nutri-score; NW, nutrient warning; RCT, randomised controlled trial; TLS, traffic light labelling system.