Evidence-Based Practice: Evidence Hierarchy

This Evidence Hierarchy Pyramid is often used to graphically represent the quality of medical research. The higher on the pyramid the more comprehensive in scope, and more rigorous the methodology and peer review. You should be looking for the highest level of research available in EBP.

If you can't locate the highest levels of research to answer a specific clinical question you should use the highest level available.  

Consult these resources to understand the language of evidence-based practice and terms used in clinical research.

Systematic Review and Meta-Analyses: These combine data from several high-quality researches exploring the same topic, usually RCTs, to offer complete insights. They minimize bias and provide the most decisive conclusions, making them essential for clinical guidelines.

Randomized Control Trial: RCTs are experiments in which participants are randomly allocated to one of two groups: Intervention or control. This approach lowers selection bias and establishes causation, yet it might be resource-costly. They minimize bias, create a controlled setting, and can use blinding to limit observer and participant bias. 

Cohort & Case-Control Studies: Cohort studies track groups over time to evaluate results, whereas case–control studies compare people with and without a disease. These observational studies provide significant insights but are less reliable than RCTs owing to potential confounding variables.

Case Series & Reports: These include thorough information on individual or group instances, frequently emphasizing unique illnesses or therapies. While beneficial for developing hypotheses, they lack generalizability. Their descriptive character makes them helpful in developing hypotheses and guiding future studies. However, they have intrinsic limitations, such as selection bias and a lack of controls.

Expert Opinion & Anecdotal Evidence: When substantial data from RCTs or cohort studies is unavailable, expert opinions and anecdotal evidence might be useful in answering complicated medical concerns. They give useful insights, particularly in developing or uncommon illnesses when data are limited. Experts rely on years of expertise to guide judgments, frequently filling key knowledge gaps. However, these perspectives are subjective, prone to human biases, and lack standardization or control.