Levels of Evidence in Evidence-Based Medicine | Free Essay Example

Levels of Evidence in Evidence-Based Medicine

Words: 636
Topic: Health & Medicine

Case Report

A case report that is also known as a case-controlled study can be referred to as the exploration of a certain phenomenon, family, or a single person. As a rule, the case report integrates quantitative and qualitative methods of research. The information collected as a result of this study relates to previous investigations or exposure to a disease, for instance. Recording both pre and post disease tests, a case report identifies interventions that were made during the study and summarizes the outcome. The nature of a case-controlled study is rather specific, thus making it remain at the lowest level of the hierarchy evidence.

Empirical Research

The empirical methods of research focus directly on the object and are based on the results of either observation or experiment. This level is associated with the theoretical study and organically interrelated with a comprehensive framework of scientific knowledge (Finotto et al., 2013). The empirical research contributes to the development of theoretical knowledge, delivering new experimental data for the subsequent generalizations that are based on the facts and experimental data. It is also based on the direct interaction of a researcher with the object under the study. The knowledge here is recorded in the form of empirical scientific facts.

Randomized Controlled Trial

The method of Randomized Controlled Trial (RCT) is the most accurate way to identify cause-and-effect relationships between treatment and outcome of disease as well as to determine their cost-effectiveness. This level of evidence hierarchy has a range of peculiarities. In particular, RCT implies the random distribution of patients to comparison groups. According to Burns, Rohrich, and Chung (2012), RCT focuses on “Items used for assessing RCTs include: randomization, blinding, a description of the randomization and blinding process, description of the number of subjects who withdrew or drop out of the study” (p. 308). At the same time, both patients and researchers know nothing about the treatment that is carried out in each of the comparison groups until the completion of the study. All groups except the experimental one receive identical treatment. The ultimate evaluation of the patients is performed in groups according to which they were separated. Speaking more widely, RCT analysis focuses on determining the degree of differences in the results between the compared groups.

Systematic Literature Review

Systematic literature reviews refer to medical research that implies the selection and study of all available data on a particular topic, for example, such as the effectiveness of a particular treatment. This research is strictly standardized. Summarizing reviews of different studies, “systematic literature reviews provide the most reliable conclusions” (Dwan, Gamble, Williamson, & Kirkham, 2013, p. 3). These findings may relate to a particular issue of treatment, prevention, and so on. Furthermore, embracing large volumes of evidence, help practitioners to understand the latest developments in the medical sphere. This level offers knowledge implementation areas and identifies gaps that require additional research. As a rule, the outcome of such studies is more reliable than the conclusions of individual studies.


A meta-analysis combines numerical analysis of similar studies that are either performed separately or as a part of a systematic review. It is regarded as rather a reliable method to obtain information on the effectiveness of treatment, especially if it is conducted based on randomized controlled trials. While the systematic review may include a variety of types of studies, meta-analysis consists of similarly structured studies. Pai, Rajesh, and Shenoy (2012) state that “systematic reviews offer evidence that is as good as the best available evidence summarized by the review” (p. 161). It uses statistical analysis to combine data obtained from individual studies and calculate the total quantitative result as if it was obtained from a single study. Thus, meta-analysis is considered to be a higher level of evidence as it is more comprehensive and relevant than a systematic review.


Burns, P. B., Rohrich, R. J., & Chung, K. C. (2012). The levels of evidence and their role in evidence-based medicine. Plastic and Reconstructive Surgery, 128(1), 305-310.

Dwan, K., Gamble, C., Williamson, P. R., & Kirkham, J. J. (2013). Systematic review of the empirical evidence of study publication bias and outcome reporting bias — An updated review. PLoS ONE, 8(7), 1-5.

Finotto, S., Carpanoni, M., Turroni, E. C., Camellini, R., & Mecugni, D. (2013). Teaching evidence-based practice: Developing a curriculum model to foster evidence-based practice in undergraduate student nurses. Nurse Education in Practice, 13(5), 459-465.

Pai, B. M., Rajesh, G., & Shenoy, R. (2012). Research design hierarchy: Strength of evidence in evidence-based dentistry. Journal of Interdisciplinary Dentistry, 2(3), 158-163.