Table 1.
Characteristics of included studies
| Characteristics | Frequency count (%) |
| Study type | |
| Interventional studies | 40 (50.0) |
| Randomised controlled trial | 17 (21.3) |
| Pre–post study | 9 (11.3) |
| Cluster randomised controlled trial | 7 (8.8) |
| Non-randomised trial | 6 (7.5) |
| Randomised trial | 1 (1.3) |
| Observational studies | 13 (16.3) |
| Prospective cohort study | 10 (12.5) |
| Retrospective cohort study | 2 (2.5) |
| Cross-sectional study | 1 (1.3) |
| Others | 27 (33.8) |
| Study protocol | 13 (16.3) |
| Conference abstract | 13 (16.3) |
| Report | 1 (1.3) |
| Publication year | |
| 1998 – 2003 | 8 (10.0) |
| 2004 – 2008 | 8 (10.0) |
| 2009 – 2013 | 15 (18.8) |
| 2014 – 2019 | 49 (61.3) |
| Country of origin | |
| USA and Canada | 31 (38.8) |
| UK and Ireland | 5 (6.3) |
| Scandinavia | 9 (11.3) |
| Western Europe | 25 (31.3) |
| Asia | 6 (7.5) |
| Australia | 3 (3.8) |
| Others | 1 (1.3) |