Approach taken to literature snowballing
| Index paper | Description of index paper | References forward snowballing | References backward snowballing | Articles excluded | Articles not located | Duplicates | Articles eligible | Additional articles included in the review (excluding duplicates) |
| Shabbir, 20123 | Systematic review | 34 | 42 | 12 | 1 | 0 | 63 | 42 |
| Aquina, 20144 | Review article | 108 | 13 | 12 | 1 | 15 | 93 | 38 |
| Hauters, 20165 | Prospective cohort study | 29 | 15 | 1 | 0 | 19 | 24 | 10 |
| Prudhomme, 20166 | Randomised control trial | 30 | 0 | 0 | 0 | 19 | 11 | 6 |
| Hotouras, 20137 | Systematic review | 115 | 42 | 12 | 6 | 37 | 102 | 26 |
| Hardt, 20138 | Systematic review | 52 | 9 | 4 | 3 | 29 | 25 | 6 |
| Additional articles suggested by experts: Brandsma, 20169 and López-Cano, 201610 | Randomised control trials | 2 | 0 | 0 | 0 | 0 | 0 | 2 |