*image adapted from from LoBiondo-Wood & Haber (2014) Nursing Research: Methods and Critical Appraisal for Evidence-Based Practice. Elsevier
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A systematic review is a comprehensive literature search on a topic in which all of the primary studies of the highest level of evidence have been systematically identified, appraised and then summarized according to an explicit and reproducible methodology.
Systematic Reviews are a gold standard for types of research studies and offer the highest level appraised evidence to answer clinical questions on a topic. In general a good systematic review will be a better guide to practice than an individual research article. Try first to find systematic reviews on your topic. If you are unable to locate them, then you can search for lower levels of non-appraised evidence (randomized controlled trials, case-control, correlational, or cohort studies, or qualitative studies)
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Meta-Analysis: A systematic review (comprehensive literature search on studies on a particular topic) that quantitatively combines the results of several studies using accepted statistical methodology in order to produce a larger sample size and draw stronger conclusions about the topic.
Meta-Analyses are a gold standard for types of research studies and offer the highest level appraised evidence to answer clinical questions on a topic. In general a good meta-analysis will be a better guide to practice than an individual research article. Try first to find either meta-analyses or systematic reviews on your topic. If you are unable to locate them, then you can search for lower levels of non-appraised evidence (randomized controlled trials, case-control, correlational, or cohort studies, or qualitative studies)
Acknowledgement:
Some info on this page is used with permission from SUNY Downstate Health Sciences University Medical Research Library. We are grateful to them!
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Clinical Guidelines as systematically developed statements or recommendations that link research and practice and serve as a guide for practitioners. Guidelines can be developed by professional organizations, government agencies, institutions or convened expert panels. Guidelines provide the recommended info for screening, treatment and decision-making for diseases and conditions.
Evidence-based guidelines are developed through a comprehensive search of research studies on a topic (often a "systematic review" type of study) which detail the quality and strength of the evidence from which the practice guideline is derived. Thus, clinical guidelines are robust summaries of how medical evidence can be applied in clinical practice.
Expert-based guidelines are sometimes developed when there is insufficient research to support an evidence-based guideline. Panels of experts create a guideline and provide a rationale for the practice recommendation. However, these guidelines do not have the same strength as evidence-based guidelines.
Therefore, it is important to know whether a specific guideline is evidence-based or expert-based when determining its robustness and if it is worthy to implement in your practice.
*description and rationale taken from: Lobiondo, G., & Harber, J. (Eds.). (2022). Nursing research: Methods and critical appraisal for evidence-based practice (10th ed.). Elsevier.
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A randomized controlled study is one in which:
Randomized controlled trials are the standard method of answering questions about the effectiveness of different therapies. If you have a therapy question, first look for a randomized controlled trial, and only go on to look for other types of studies if you don't find one.
Acknowledgement:
Some info on this page is used with permission from SUNY Downstate Health Sciences University Medical Research Library. We are grateful to them!
Example:
A Controlled Trial (Without Randomization):
While not as strong and unbiased as randomized controlled trials, these Controlled Trials without Randomization can still provide helpful data, especially in cases where it is unethical or impossible to randomize the subjects (for example, because of prison safety protocols, researchers may not have access to an entire prison population, but only to certain groups within that population)
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A Cohort Study is an observational study in which the researcher simply observes an outcome without intervening. A group demonstrating a characteristic of interest (health condition, behavior...etc.) are followed prospectively over time while being compared to a similar group that does not demonstrate the characteristic of interest. Specific measures in the designated group (patient quality of life, disease progression, mortality rates…etc.) are compared to those reported for the comparison cohort.
For instance, since a randomized controlled study that required people to smoke in order to test effects on their health would be unethical, a reasonable alternative would be a study that identifies two groups: a group of people who already currently smoke and a group of people who do not, and then follows them forward through time to see what health problems they develop.
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A Case Control study (sometimes called a "retrospective cohort study") is an observational study that compares a group of patients who developed a specific illness, had an adverse reaction associated with a treatment or behaved in a particular way with a different group of patients who did not exhibit those characteristics. The study looks retrospectively (back in time) in an attempt to identify risk factors and determine uncover a potential relationship between those risk factors and the illness, reaction or behavior.
These studies can be helpful to answer prevention or prognosis questions
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Cross-Sectional studies are observational studies that describe a population at a certain point in time. The subjects in the population share a variable(s) and the study aims to look at the relationship between that and other variables in the subjects. These studies can locate correlations but not causal relationships.
These studies are helpful to explore relationships, differences and comparisons, or both.
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Case Reports or Case Studies are reports on a single patient usually written in a detailed story format. They can include quantitative and/or qualitative data and so can contain different methodological approaches.
Case Series are collections of reports on individual patients treated in a similar manner
These studies are helpful if your patient has a unique condition/illness that is not well-known or studied in the medical community. They can detail important variations of a condition, uncover patterns consistent across a set of cases or highlight unexpected results that may offer useful info or provides the grounds for future study.
A search for case series or case reports may reveal information that will assist in a diagnosis. However, for any reasonably well-known condition you should also be able to get better evidence in other types of research studies and should not rely on case reports alone.
Acknowledgement:
Some info on this page is used with permission from SUNY Downstate Health Sciences University Medical Research Library. We are grateful to them!
Example:
A qualitative study attempts to understand the meaning of a phenomenon through the context of patients' experience, attitudes, motivations and behaviors. While quantitative studies gather data in the form of “numbers and statistics” qualitative studies instead gather "words and ideas" as data through a descriptive, inductive approach. These studies employ research methodologies such as interviews, focus groups, ethnographic observations, case studies, grounded theory and phenomenology.
Qualitative studies are helpful for uncovering the “why” behind a research question with the understanding that patients’ experiences and behaviors are socially and contextually dependent and thus cannot always be quantified. By uncovering the nuances of the “why,” researchers can then use that knowledge to improve health outcomes and patient experiences.
description of cohort studies adapted from: https://pressbooks.library.upei.ca/montelpare/chapter/types-of-research-designs/