number of study quality. confounders controlled for that may have an effect on the outcome? ls/are the authors' If not there could be potential issues with conclusions bias. justifiable? Can the study If not there could be potential issues with results be study quality. applicable to the target population? Levels of Evidence for Cohort and Case-Control Study 2++: High quality cohort or case-control with low risk of bias/confounding and highly likely causal relationship. 2+: High quality cohort or case-control with low risk of bias/confounding and moderately likely causal relationship. 2-: Cohort or case-control study with high risk of bias/confounding and a causal relationship Is not likely IV. Non-Analytic Studies (Cross-Sectional , Ecoloaical, or Case Serles/Case Study) Levels of Evidence for Non-Analytic Studies 3: Non-Analytic Studies (Cross-Sectional, Ecological, or Case Series/Case Study) V. Expert Opinion Levels of Evidence for Expert Opinion 4: Expert Opinion VI. Laboratory Study uslna in-vitro or Animal Model Levels of Evidence for Laboratory Studies No rating GRADES OF RECOMMENDATION USING ARTICLES A 2: 1 meta-analysis/systematic review of randomized controlled trials rated as 1++ directly applicable to target population OR 2: 1 Randomized controlled trial rated as 1 ++ directly applicable to target population