The levels of evidence (LOE) are a classification system for the quality of scientific evidence. It assesses the strength of the evidence supporting a hypothesis or theory. There are seven levels of evidence: observational studies, randomized controlled trials, quasi-experimental studies, correlational studies, experts’ opinions, clinical data, and case reports. Observational studies collect data on people’s habits and health outcomes without intervening in their lives (Grant et al., 2022). One example of this practice change that could result from observational studies is if they found a link between eating red meat and developing cancer. It may include educating people to reduce the red meat they eat.
Evidence from experts’ opinions is individual experts’ opinions based on their experience and expertise (Shanthanna et al., 2020). An example of a practice change that could result from this evidence is if a doctor changes their mind about treatment after discussing it with another doctor who has more experience with that particular treatment. Clinical data is a collection of data from patients who have received treatment for a particular condition (Blonde et al., 2018). For example, suppose a drug company tests a new prescription medication in a clinical trial. In that case, the results of that trial could be used to decide whether or not to approve the drug for use by the general public.
A correlational study is a study that looks at the relationship between two variables (Berryman et al., 2018). For example, a study might examine the relationship between smoking and lung cancer. A case report is a study that looks at one specific case (Sayre et al., 2017). For example, a study might look at the relationship between smoking and lung cancer in one specific person. Practice changes that could result from correlational studies would include increasing public awareness of the correlation between smoking and lung cancer; it could entail restricting smoking in public places.
Randomized controlled trials (RCTs) are experiments in which people are randomly assigned to different groups (Connolly et al., 2018). One group receives the treatment being studied, while the other group receives a different treatment. Example of a practice change that could result if a doctor decides to start prescribing a new medication to her patients after seeing positive results from a randomized controlled trial. Quasi-experimental studies are experiments in which people are not randomly assigned to groups but are chosen based on their similarity in certain characteristics (Galama et al., 2018). An example of a practice change that could result from quasi-experimental studies would be changing the order in which different treatments are given to a patient (trying one treatment before another).
References
Berryman, C., Ferguson, C. J., & Negy, C. (2018). Social media use and mental health among young adults. Psychiatric Quarterly, 89(2), 307-314. Web.
Blonde, L., Khunti, K., Harris, S. B., Meizinger, C., & Skolnik, N. S. (2018). Interpretation and impact of real-world clinical data for the practicing clinician. Advances in Therapy, 35(11), 1763-1774. Web.
Connolly, P., Keenan, C., & Urbanska, K. (2018). The trials of evidence-based practice in education: A systematic review of randomised controlled trials in education research 1980–2016. Educational Research, 60(3), 276-291. Web.
Galama, T., Lleras-Muney, A., & van Kippersluis, H. (2018). The effect of education on health and mortality: A review of experimental and quasi-experimental evidence. Web.
Grant, W. B., Boucher, B. J., Al Anouti, F., & Pilz, S. (2022). Comparing the evidence from observational studies and randomized controlled trials for nonskeletal health effects of vitamin D. Nutrients, 14(18), 3811. Web.
Sayre, J. W., Toklu, H. Z., Ye, F., Mazza, J., & Yale, S. (2017). Case reports, case series–From clinical practice to evidence-based medicine in graduate medical education. Cureus, 9(8). Web.
Shanthanna, H., Strand, N. H., Provenzano, D. A., Lobo, C. A., Eldabe, S., Bhatia, A., Wegener, J., Curtis, K., Cohen, S. P., & Narouze, S. (2020). Caring for patients with pain during the COVID-19 pandemic: Consensus recommendations from an international expert panel. Anaesthesia, 75(7), 935–944. Web.