Choose the Right Study
It's essential that you are looking at the type of study that can reasonably answer your question. For example, if you're interested in what might have caused a disease, go with a case-control study or retrospective study where the researchers are looking back in time by examining patients' medical records. Or if you're interested in the outlook or prognosis of a disease, you'll want a cohort study that follows people over time to see how symptoms develop.
Sometimes you can't pick a study that is the strongest evidence due to safety concerns. For example, it wouldn't be ethical to conduct an RCT where a group of pregnant people is given cigarettes to test what will happen. In that case, you'll need to go with a different study design.
If your disease is rare, you'll have to take what you can get. There may not be enough people with that disease to conduct an RCT.
| Type of Question |
Study Design That Answers That Question (In Order of Preference) |
| What are treatments for this condition? Is one therapy more effective than another? | Randomized control trial |
| How accurate is this diagnostic test? | Independent, blind comparison to a gold standard |
|
What is the outlook (prognosis, progression, survival, outcomes) for this condition? |
Cohort study Case-control study Case series |
|
What might cause this condition?
|
RCT Cohort study Case-control study Case series |
| Are there possible negative effects of a treatment or exposure? | Case-control study |
| How can we reduce the risk of this condition? |
RCT Cohort study Case-control study |
| What might prevent this condition? |
RCT Cohort study Case-control study |
| Is one treatment more cost-effective than another? | Economic analysis |
| What will be the quality of life for the patient after being given the proposed intervention? | Qualitative study |
| What is the cost-effectiveness of this treatment? | Economic analysis |
Identify the Study Design
A fair number of papers will include their study design in their titles. Systematic reviews, by and large, will state that they're a systematic review in the title with few exceptions. Otherwise, check the methods section.
Or, the study design may be listed in PubMed. For example, if you look at this study and scroll all the way to the bottom of the page, you'll see Case Control Studies appear as a MeSH term. Other studies may also have a "Publication Type" section listed near the MeSH terms.
