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PHYT 7014: Systematic Reasoning and Scientific Investigation I: EBP

A guide to literature searching.

Defining EBP

Evidence-Based Practice (EBP) is the framework for your clinical decision-making process. It is the integration of

  • your knowledge, skills, and past experience (Clinical Expertise);
  • the unique preferences, concerns and expectations of your patient (Patient Characteristics); and
  • valid and clinically relevant research (Best Evidence).

 

      

 

Types of Clinical Questions

Therapy - What is the treatment for a disease?

Diagnosis - power of a test to differentiate between those with and without a disease?

Prognosis - a patient’s likely course over time due to factors other than interventions?

Etiology/Harm - effects of potentially harmful agents on the patient?

5 A's - Steps for Acquiring Information

                    

               - Review the Situation (Assess)

             - Define the clinical problem as a question (Ask)

             - Select resources, design a strategy, and search for the

               answer (Acquire)

             - Summarize the evidence yield (Appraise)

             - Apply the evidence (Apply)

Levels of Evidence

Levels of Evidence help you target the likely best type of evidence.

Level of Evidence Type of Study
1a Systematic reviews of randomized controlled trials (RCTs)
1b Individual RCTs with narrow confidence interval
2a Systematic reviews of cohort studies
2b Individual cohort studies and low-quality RCTs
3a Systematic reviews of case-control studies
3b Case-controlled studies
4 Case series and poor-quality cohort and case-control studies
5 Expert opinion

Physiopedia. (2018). Grades and levels of evidence. Retrieved from http://www.physio-pedia.com/grades_and_levels_of_evidence

Study Design

 

Type of Question Suggested Best Type of Study
Therapy RCT > prospective cohort
Diagnosis Prospective, blind comparison to a gold standard
Etiology/Harm RCT > cohort > case control > case series
Prognosis cohort study > case control > case series
Prevention RCT > cohort study > case control > case series
Clinical Exam prospective, blind comparison to gold standard
Cost economic analysis

Study Types

Study Type Description
Quasi-experimental

An empirical study used to estimate the causal impact of an intervention on its target population without random assignment. It shares similarities with the traditional experimental design or randomized controlled trial, but it specifically lacks the element of random assignment to treatment or control.

Case Control Studies

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/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.
Cohort 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.  
Cross-Sectional Describe the relationship between diseases and other factors at one point in time in a defined population. Cross sectional studies lack any information on timing of exposure and outcome relationships and include only prevalent cases.  They are often used for comparing diagnostic tests.  Studies that show the efficacy of a diagnostic test are also called prospective, blind comparison to a gold standard study. This is a controlled trial that looks at patients with varying degrees of an illness and administers both diagnostic tests — the test under investigation and the “gold standard” test — to all of the patients in the study group. The sensitivity and specificity of the new test are compared to that of the gold standard to determine potential usefulness.
Meta-Analysis Thoroughly examines a number of valid studies on a topic and mathematically combine the results using accepted statistical methodology to report the results as if it were one large study.
Qualitative Research Answers a wide variety of questions related to human responses to actual or potential health problems.The purpose of qualitative research is to describe, explore and explain the health-related phenomena being studied.
Randomized Controlled Trials (RCTs) 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.  
Retrospective or Historical Cohort Follows the same direction of inquiry as a cohort study.  Subjects begin with the presence or absence of an exposure or risk factor and are followed until the outcome of interest is observed.  However, this study design uses information that has been collected in the past and kept in files or databases.  Patients are identified for exposure or non-exposures and the data is followed forward to an effect or outcome of interest.
Systematic Review Focuses on a clinical topic and answers 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.