Levels of Evidence
Evidence-based practice, abbreviated as EBP, integrates patient preferences, clinical expertise, and research evidence to enhance personal-based care. Evidence-based practice is presumed to be a form of a problem-solving approach. In determining the effectiveness of this practice or intervention, a system of rating evidence was developed. The system of rating is commonly termed as the levels of evidence, also called hierarchy of evidence. Exploring the seven levels of evidence forms the central focus of this discussion.
In a health setup, it’s significant to note that evidence levels are attributed to a research study based on their usability to patient care, validity, and design methodology quality. The levels include:
Level I- the level includes all the evidence from a meta-analysis or a systematic review of all pertinent evidence-based clinical practices or randomized controlled trial (RCT). The evidence is based on systematic reviews of various randomized controlled trials having similar outcomes.
Level II involves evidence gathered from at least one large multi-site RCT (a well-designed random controlled trial).
Level III- involves evidence collected from a well-designed controlled trial. Note in this case; there is no randomization.
Level IV- this involves evidence from cohort studies or well-designed case-control studies.
Level V- involves evidence from qualitative and systematic reviews of descriptive studies.
Level VI- the level only includes evidence from a single qualitative or descriptive study.
Level VII- this final stage involve evidence from expert committee report and opinions from the authorities.
An example and the type of practice change that could exist from each level includes an Evidence Classification Scheme for a Diagnostic Measure based on the U.S Department of Health and Human Services. The scheme includes various classes, which include:
Class I- this involves a prospective study in an extensive spectrum of individuals with the suspected condition. In this case, the test is based on a blinded evaluation that enhances the assessment of applicable tests of diagnostic accuracy. The stage uses a ‘gold standard’ practice for the case definition.
Class II includes a well-designed retrospective study of a broad spectrum of an individual with a non-suspected condition. The class may involve comparing a broad spectrum of controls with a prospective study of a narrow spectrum of individuals with a suspected condition. Still, the test is based on a blinded evaluation, thus enhancing the assessment of applicable diagnostic accuracy tests.
Class III involves a gathered retrospective study evidence where either individual with controls or established conditions is based on a narrow spectrum. The test is still based on a blinded evaluation.
Class IV- includes evidence gathered from descriptive case series (no controls) or expert opinions. In this case, the test is not based on a blinded evaluation.