Strength of Evidence Scale

High: Image clinadhdfu1.jpgThere are consistent results from good-quality studies. Further research is very unlikely to change the conclusions.
Moderate: Image clinadhdfu2.jpgFindings are supported, but further research could change the conclusions.
Low: Image clinadhdfu3.jpgThere are very few studies, or existing studies are flawed.
Insufficient: Image clinadhdfu4.jpgResearch is either unavailable or does not permit estimation of a treatment effect.

PubMed Health. A service of the National Library of Medicine, National Institutes of Health.