PRISMA flow chart to select literature for analysis.
| Procedure | Identification of new studies via databases | |
| Identification | Records identified from databases (n=13,317) | |
| Screening | Formal screening, records screened (n=613) | Records excluded (n=12,704) |
| 1st Content screening, records screened (n=576) | Records excluded (n=37) | |
| 2nd Content screening, records screened (n=99) | Records excluded (n=477) | |
| 3rd Content screening, records screened (n=86) | Records excluded (n=13) | |
| Included | Total studies included in review (n=86) | |