Note that the extent of proof in the aforementioned grading system relies partially on the quality of the studies. This grading was notably relevant for experimental research wherein the level of proof would change from Level 1 to Level 2 primarily based on whether or not the randomized managed trials have necessary limitations. A single investigator assessed the standard of the RCTs included in this systematic evaluate using the validated guidelines developed by Downs and Black . Cross-sectional research, case-control studies, cohort studies and intervention research have been eligible for inclusion within the systematic review.
