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General characteristics of the included studies.
| Characteristics | Studies (n=22) | ||
| Study design | |||
|
|
Randomized controlled trial | 4 | |
|
|
Cohort (prospective) | 12 | |
|
|
Cohort (retrospective) | 4 | |
|
|
Others | 2 | |
| Origin of study | |||
|
|
United States | 13 | |
|
|
Canada | 2 | |
|
|
Australia | 2 | |
|
|
India | 2 | |
|
|
Others | 3 | |
| Year of publication | |||
|
|
2014-2018 | 13 | |
|
|
2008-2013 | 9 | |
