As massage therapists, we’re often told we need to keep up with the latest research to make sure our practice is as evidence-based as possible. Unfortunately, many of us have very little experience in reading and evaluating research, so keeping up with the newest evidence can be intimidating. How do we know if a particular piece of research is good, and should be considered when we create our treatment plans?
Hierarchy of Evidence
Before we delve into the details of what makes a good study, it’s important to understand that scientific evidence forms a hierarchy. The higher up the hierarchy, the better the quality of the evidence. Although there are some variations on the hierarchy, some including more levels than others, the order is always the same. The most common levels include, from top to bottom:
Systematic Reviews compare many studies on the same topic and evaluate them to see if the conclusions about the topic are consistent.
Randomized-Controlled Trials (RCTs) are what we encounter often in published massage therapy research. They are experimental studies where one group is exposed to an intervention (like massage), and another group is exposed to a placebo (sham) treatment, no treatment at all, or sometimes both if there are enough participants for three groups. The participants should be randomized (placed randomly) into those groups, in order to minimize the chances of factors other than the massage treatment influencing the outcome of the study.
Case Control Studies and Cohort Studies are types of observational studies. In these types of studies, experimenters don’t try to control who is or isn’t exposed to the intervention (like in an RCT); they just observe the effect of the intervention on a group of people. In cohort studies, the ‘cohort’ is a group of people who have some common link (like all being born around the same time, or of a particular race), whereas in case control studies participants are chosen because they have a common health problem.
Case Series and Case Reports are descriptions of a particular patient’s experience with a health problem – their symptoms, how it’s impacting their lives, their daily routines, what treatments they received, their responses to those treatment(s), and so on. Case reports involve a single patient, case series involve multiple patients, and neither involves controls or randomization. Case studies and case reports can provide important information, but they cannot demonstrate a cause-and-effect relationship between the massage treatment and the outcome.
Anecdotes are personal experiences a patient describes regarding a particular treatment. They are highly subjective, and often don’t include any information aside from the benefit they believe they experienced from the treatment.
Animal Studies are experiments completed on animals. Their purpose, in health care, is to gather preliminary information about the effect of an intervention, and how it might impact human patients. However, results from animal studies are often exaggerated to support claims that haven’t been properly demonstrated in humans.
This article focuses mostly on RCTs, since they’re the most common type of published massage therapy research accessible to most of us, and they are fairly high up the evidence hierarchy. However, not all RCTs (or experimental studies) are designed equally. Being higher up on the hierarchy is good, but it’s not a guarantee that a particular piece of research is well designed.
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