Characteristics of included articles
| Characteristic | Frequency (n=27) | Per cent (100%) |
| Country of first author | ||
| USA | 7 | 25.9 |
| UK | 6 | 22.2 |
| The Netherlands | 5 | 18.5 |
| China | 3 | 11.1 |
| France | 3 | 11.1 |
| Thailand | 2 | 7.4 |
| Canada | 1 | 3.7 |
| Year of publication | ||
| 2010–2014 | 8 | 29.6 |
| 2015–2019 | 13 | 48.2 |
| 2020–2021* | 6 | 22.2 |
| Type of study | ||
| Study design | ||
| Observational study | 20 | 74.1 |
| Non-randomised experimental study | 1 | 3.7 |
| Randomised controlled trial | 6 | 22.2 |
| Type of digital intervention | ||
| Web-based testing | 23 | 85.2 |
| Video-assisted testing services, web-based testing and electronic health records | 2 | 7.4 |
| Mobile applications | 1 | 3.7 |
| Social media | 1 | 3.7 |
| Sample collection methods | ||
| Postal-based self-sample collection | 18 | 66.7 |
| Self-sample collection and interpretation | 6 | 22.2 |
| Lab-assisted sample collection | 2 | 7.4 |
| Self-sample collection and interpretation; self-sample collection and postal | 1 | 3.7 |
*Only includes 2 years of data compared with 5 years in other categories.