Table 1.

Index of scientific quality

Metric	Key question	Criterion for “No”	Criterion for “Partially”	Criterion for “Yes”
Applicability	Is it clear to whom the information in the report applies (i.e. to which population the evidence is applicable)?	Potentially misleading	Minor lack of clarity	Minimal ambiguity
Opinions versus Facts	Are facts clearly distinguished from opinions?	Potentially misleading	Statements are attributed to sources, but the underlying evidence is ambiguous	The evidence underlying the main points is clearly cited
Validity	Is the assessment of the credibility (validity) of the evidence clear and well-founded (not misleading)? (In making this assessment take into account only the explicit message, not the implicit assessment.)	Not done or potentially misleading	Study design or type of evidence reported, but not properly assessed	Strength of the research methods adequately assessed
Magnitude	Is the strength or magnitude of the findings (effects, risks, or costs) that are the main focus of the article clearly reported?	Not done or potentially misleading	The magnitude of effects or risks is reported incompletely or ambiguously	Magnitude of main effects or risks clearly reported (including, if relevant, the baseline risk and dose-response relationship
Precision	Is there a clear and well-founded (not misleading) assessment of the precision of any estimates that are reported or of the probability that any of the reported findings might be due to chance?	Not done or potentially misleading	Indirectly or not completely; e.g. sample size reported but not properly assessed	Statistical significance or precision adequately assessed
Consistency	Is the consistency of the evidence (between studies) considered and is the assessment well-founded (not misleading)? (In making this assessment take into account only the explicit message, not the implicit assessment.)	Not done or potentially misleading	More than one study discussed, some ambiguity re how many studies there are or their consistency	Number of studies and consistency (with respect to the direction of their findings) clearly reported
Consequences: Benefits	Are all of the important consequences (benefits) of concern relative to the central topic of the report identified?	Potentially misleading	Potentially important benefits not considered	Most important benefits are clearly identified
Consequences: Risks and Costs	Are all of the important consequences (risks and costs) of concern relative to the central topic of the report identified?	Potentially misleading	Potentially important risks or costs not considered	Most important risks or costs are clearly identified
Global	Based on your answers to the above questions, how would you rate the overall scientific quality of the report?	Critical or extensive shortcomings	Potentially important but not critical shortcomings	Minimal shortcomings