What does the research show?
Every day new research comes out claiming to provide evidence that will advance the practice of medicine or improve guidelines for the prevention or management of disease.
Good research helps to give healthcare providers the tools to practice using the best available evidence.
Evidence Based Practice (EBP)
EBP integrates a physician’s clinical expertise with the best available evidence into the decision making process for patient care.
The best evidence is clinically relevant research that is conducted using sound methodology.
When you see a study or someone says “the research says”, it is helpful to put this into perspective as the validity and reliability of many studies are lacking. Therefore, any recommendations extrapolated from these studies should be taken with caution.
Studies generally have a PICO
Population studied – The participants with a problem or condition
Intervention – The dependent (outcome) variable and independent (treatment) variable. For example, in an acupuncture study, acupuncture would be the independent variable and pain relief the dependent variable.
Comparison – e.g. control group (those not receiving the intervention)
Outcome – What were the results of the intervention?
Parts of a study
A research article generally has five sections:
- Abstract- A brief summary of the study and the conclusions.
- Introduction-The significance of the study, which includes citations from other studies in the form of a literature review, and the research question/objective.
- Methods- The participants, procedures and instrumentation (tools used).
- Results- The findings (usually in terms of statistical significance).
- Discussion and conclusion- Implications, limitations and recommendations.
Types of studies
There are a number of different study designs. These each have advantages and disadvantages as well as varying Levels of Evidence (LOE).
Case series and case reports– A collection of reports on the treatment of individual patients or a report on a single patient. Case series/reports do not have a control group to compare outcomes, and have little statistical validity.
Case control studies are studies in which patients who already have a specific condition are compared with people who do not have the condition.
Researchers looks back to identify factors that might be associated with the condition or illness.
These often rely on medical records and patient recall for data collection. They are generally less reliable than randomized controlled trials and cohort studies because showing a statistical relationship does not confer causation.
Cohort studies identify a group of individuals who are currently undergoing a particular treatment or have had exposure to a variable, and then follows them forward over time, comparing their outcomes with a similar group that has not been affected by the treatment or exposure being studied.
Cohort studies are observational and not reliable since there can be a number of confounding (outside) variables.
Randomized controlled clinical trials (RCTs) are carefully planned experiments that introduce a treatment or exposure to study its effect on real patients.
RCTs include methodologies that reduce the potential for bias (e.g. randomization and blinding) and allow for comparison between intervention groups and control (no intervention) groups.
An RCT can provide sound evidence of cause and effect.
Systematic reviews focus on a topic and answer a specific question. They involve an extensive literature search to identify studies with sound methodology.
These studies are reviewed, assessed for quality, and then summarized according to the predetermined criteria. Like meta-analysis, these can be subject to bias in that the reviewer can pick and choose those studies that support their view point.
A meta-analysis thoroughly examines a number of valid studies on a topic and mathematically combines the results using accepted statistical methodology to report the results as if it were one large study.
As with systematic reviews, a meta-analysis can have a bias in that the authors can “cherry pick” those studies that they feel will provide the evidence they are looking for that supports their view.
On the other hand, these types of studies can provide strong Level 1 evidence
Cross-sectional studies 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.
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. The focus in qualitative research is on the subject’s experience along with other psychosocial factors.
Retrospective 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.
This type of study uses information that has been collected in the past and kept in files or databases. Subjects are identified for exposure or non-exposures and the data is followed forward to an effect or outcome of interest.
- Who funded the study? If a study was funded by a drug company like Merck or a chemical company like Monsanto, this could be considered a conflict of interest as they would have a vested interest in the outcome.
- Did the authors have any financial or other connections? If so, this would be considered a potential conflict of interest.
- Did there appear to be unfair bias?
- How large was the sample size that was studied? A sufficient sample size would be at least 30.
- What journal or publication was the study published in? Was it a reputable journal or just popular literature?
The next time someone states, “the research shows…”, you should now be in a better position to evaluate their statement (and the research).