The Levels of Evidence and their Importance

Topic 3 DQ 1
What levels of evidence are present in relation to research and practice, and why it is important regardless of the method you use?
EXAMPLE BELOW FROM PEERS
Re:Topic 3 DQ 1
Evidence-based practice is a conscientious, problem-solving approach to clinical practice that incorporates the best evidence from well-designed studies, patient values and preferences, and a clinician's expertise in making decisions about a patient's care. Unfortunately, no standard formula exists for how much these factors should be weighed in the clinical decision-making process. However, there are a variety of rating systems and hierarchies of evidence that grade the strength or quality of evidence generated from a research study or report. Being knowledgeable about evidence-based practice and levels of evidence is important to every clinician as clinicians need to be confident about how much emphasis they should place on a study, report, practice alert or clinical practice guideline when making decisions about a patient's care. An understanding of how various levels of evidence are reported and how this literature is organized will help the searcher retrieve the highest levels of evidence for a particular clinical question. High levels of evidence may not exist for all clinical questions because of the nature of medical problems and research and ethical limitations. Evidence-based information ranges from Level A (the strongest) to Level C (the weakest)
LEVEL A: Evidence obtained from:
Randomized control trials: the classic “gold standard” study design. In RCTs, subjects are randomly selected and randomly assigned to groups to undergo rigorously controlled experimental conditions or interventions.
Systematic review or meta-analysis of all relevant RCTs. A systematic review is a critical assessment of existing evidence that addresses a focused clinical question, includes a comprehensive literature search, appraises the quality of studies and reports results in a systematic manner. Meta-analysis is a study design that uses statistical techniques to combine and analyze data from many RCTs.
Clinical practice guidelines: based on systematic reviews of RCTs. Evidence-based clinical practice guidelines provide the strongest level of evidence to guide clinical practice because they are based on rigorous reviews of the best evidence on specific topics.
LEVEL B: Evidence obtained from:
▪ Well-designed control trials without randomization: In this type of study, random assignment is not used to assign subjects to experimental and control groups. Therefore, this type of research is less strong in internal validity because it can't be assumed the subjects in the study are equal on major demographic and clinical variables at the beginning of the trial. Frequent problems with this type of study include intentional or unintentional bias in sample enrollment; non-blinding, unclear criteria for participant selection; or unreliable or invalid tools.
▪ Clinical cohort study: an examination of groups of people who have common characteristics or exposure experiences to compare outcomes in those exposed vs. outcomes in those not exposed (e.g., development of heart disease after exposure or non-exposure to 10 years of secondhand smoke).
▪ Case-controlled study: use of an observational approach in which subjects known to have a disease or outcome are compared with subjects known not to have that disease or outcome. Subjects are matched on characteristics so that they are as similar as possible except for the disease or outcome. Case-control studies are generally designed to estimate the odds (using an odds ratio) of developing the studied condition or disease and can determine if an associated relationship exists between the condition/disease and risk factors.
▪ Uncontrolled study: studies that do not control participant selection or interventions (e.g., a convenience sample, such as patients on a given unit, may be studied because it's the only group reasonably available).
▪ Epidemiological study: studies that observe people over a long time to determine risk or likelihood of developing diseases. These studies include retrospective database searches or prospective studies that follow a population over time.
Qualitative study/quantitative study: descriptive, word-based phenomena, such as symptoms, behaviors, culture and group dynamics. Quantitative studies use statistical methods to establish numerical relationships that are correlational or cause and effect.
LEVEL C: Evidence obtained from:
Consensus viewpoint and expert opinion: a study that obtains agreement about specific practices from all clinical experts on a review panel. Expert opinion involves obtaining agreement from a majority of clinical experts on a review panel. Note: This level of evidence is used when there are no quantitative or qualitative studies in a particular area.
Meta-synthesis: a systematic review that synthesizes findings from qualitative studies using an interpretive technique to bring small study findings, such as case studies, to clinical application.
LEVEL ML (multilevel): clinical practice guidelines, recommendations based on evidence obtained from:
More than one level of evidence as defined in On Course Learning's rating system.
Reference:
Evidence Based Medicine: Levels of Evidence. Retrieved on May 25, 2016 from http://researchguides(dot)uic(dot)edu/c.php?g=252338&p=1683348
Evidence-Based Practice: Levels of Evidence. Retrieved on May 25, 2016 from http://ce(dot)nurse(dot)com/ebp.aspx


Re:Topic 3 DQ 1
The purpose of determining the level of evidence and then critiquing the study is to ensure that the evidence is credible (eg, reliable and valid) and appropriate for inclusion into practice. The way this is done is by nurses using the levels of evidence to determine the strength of the research study by assessing the findings, and evaluating the evidence for potential implementation into best practices. The levels of evidence rate the study design, however doesn't determine the relevance to clinical practice (Peterson, Barnason, Donnelly, Hill, Miley, Riggs & Whiteman, 2014).

The highest levels of evidence are from systematic randomized controlled trials despite their inability to answer all questions related to clinical practice. (Peterson, Barnason, Donnelly, Hill, Miley, Riggs & Whiteman, 2014). It's important to have levels of evidence to determine if the research is relevant to clinical practice. Clinicians need to determine if the evidence provided is appropriate for the patient population they are treating.

References
Peterson, M. H., Barnason, S., Donnelly, B., Hill, K., Miley, H., Riggs, L., & Whiteman, K. (2014). Choosing the Best Evidence to Guide Clinical Practice: Application of AACN Levels of Evidence. Critical Care Nurse, 34(2), 58-68 11p. doi:10.4037/ccn2014411