Table 1.

Six most frequent approaches to RLRs (adapted from Tricco et al. [13]).

Domain	Approach 1	Approach 2	Approach 3	Approach 4	Approach 5	Approach 6
Literature search	More than one database, only published data	Update of previous literature search	More than one database, grey literature included
Search limit	Date and language	None	Date and language	Date or language	Date	Date and language
Screening	One reviewer					Two reviewers
Data extraction	One reviewer and one verifier	One reviewer
Risk of bias appraisal	One reviewer and one verifier	Not performed			One reviewer	Not performed
Overall assessment	Highly feasible and timely, having the lowest potential risk of bias	Highly feasible and timely	Moderate	Moderate	Highly comprehensive, but low-ranking in terms of feasibility and timeliness	Highly comprehensive, but low-ranking in terms of feasibility and timeliness