Appraising articles from the primary literature
Evidence-Based Point of Care resources (Hunting Tools) provide evaluations of the primary literature and assign a grade to the recommendations based on a variety of taxonomies. Physicians can rely on these resources for clinical information that is based on continuous scans and evaluations of the medical literature.
At times, a physician will need to read the primary literature and make his or her own determination of the validity, relevance, and quality of a study.
Information Mastery includes the ability to appraise articles from the primary literature for applicability to one's patient(s); feasibility of the intervention to the physician's practice; whether or not the information in the article is practice-changing.
Worksheets for appraising journal articles
Appraisal worksheets from the Oxford Centre for Evidence-Based Medicine.
There are many types of studies. In order of evidence (highest to lowest), the most common studies are:
A Meta-analysis will thoroughly examine a number of valid studies on a topic (very often RCTs) and mathematically combine the results using accepted statistical methodology to report the results as if it were one large study.
Systematic Reviews focus on a clinical topic and answer a specific question. An extensive literature search is conducted to identify studies with sound methodology. The studies are reviewed, assessed for quality, and the results summarized according to the predetermined criteria of the review question.
Randomized controlled clinical trials are carefully planned experiments that introduce a treatment or exposure to study its effect on real patients. They include methodologies that reduce the potential for bias (randomization and blinding) and that allow for comparison between intervention groups and control (no intervention) groups. A randomized controlled trial is a planned experiment and can provide sound evidence of cause and effect.
Cohort studies identify a group of patients who are already taking a particular treatment or have an exposure, follow them forward over time, and then compare their outcomes with a similar group that has not been affected by the treatment or exposure being studied. Cohort studies are observational and not as reliable as randomized controlled studies, since the two groups may differ in ways other than in the variable under study.
Case control studies are studies in which patients who already have a specific condition are compared with people who do not have the condition. The researcher looks back to identify factors or exposures that might be associated with the illness. They often rely on medical records and patient recall for data collection. These types of studies are often less reliable than randomized controlled trials and cohort studies because showing a statistical relationship does not mean than one factor necessarily caused the other.
Case series and Case reports consist of collections of reports on the treatment of individual patients or a report on a single patient. Because they are reports of cases and use no control groups to compare outcomes, they have little statistical validity; however, they are still very important for reporting on rare or new clinical conditions.
Adapted from: Introduction to Evidence-Based Practice, Duke University Medical Center. http://guides.mclibrary.duke.edu/c.php?g=158201&p=1036068
Clinical Question Categories
Depending of the clinical/research question, a certain study type can often provide the best answer. Keep in mind that RCTs are not always available or even possible for every therapy/intervention, and that certain questions are appropriately answered by studies that are lower on the EBM pyramid.
|Question Category||Study Type|
|Diagnosis||prospective, blind comparison to a gold standard|
|Prognosis||cohort>case control>case series|
Questions to consider when appraising an article
Is the study outcome something that my patient(s) would care about (Patient-Oriented vs. Disease-Oriented Evidence)?
Is the problem studied common to the physician's practice, and is the intervention/recommendation feasible in his/her practice?
Will the information found in the article require the physician to change his/her practice?
Are the patients in the study similar to the physician's patients?
For RCTs, were the subjects randomly assigned into at least two groups?
Were the intervention and control groups similar?
Who funded the study?
Who published the article?
For detailed analysis, see the Box "Worksheets for appraising journal articles" on this guide.