The Blind Leading the Blind? Clinical Study Design
- Jackie Lochridge
- 10 minutes ago
- 3 min read
Why Clinical Trials?
When new treatments are being developed, there comes a point when they must be evaluated on humans. This ensures that new treatments are both safe and effective. In the United States, human testing occurs in multiple phases called clinical trials. Later phases of these trials are aimed at ensuring that new drugs have a positive effect on patients with the target condition and continuing to document side effects.
Clinical trials where a treatment is being provided are called interventional studies. These studies are designed to remove as much bias as possible in order to provide accurate data. To that end, there are a few frequently-used study designs and features.
Clinical Blindness
You've probably heard the phrase "randomized double-blind placebo-controlled trial" at some point. That is a very common and well-established study design in which neither the doctors providing interventions nor the participants receiving them know if they are getting a trial treatment or a placebo (a.k.a. sugar pill). Randomly assigning a group of participants to the placebo group assures that changes are due to the intervention and would not have reasonably happened without it. For example, in a trial for a new blood pressure medication, participants in the treatment group had an average blood pressure reduction of 22 mm Hg systolic and 11 mm Hg diastolic, where participants in the placebo group experienced no change.
Who is Blind and How Many Arms?
While double-blind trials are very common, triple-blind and single-blind trials also exist. In the case of a single-blind study, participants don't know if they are receiving a treatment of placebo, but the doctors, sponsor, and those analyzing data do. In a triple-blind study, doctors, participants, and data analysts are blinded to which group is receiving intervention and placebo. Whole using a placebo as a control is very common, other studies seek to compare a new treatment to an existing treatment. Either to show that the new treatment is better (more effective or with fewer side effects) or similar to current standard treatments. These studies are less common than placebo-controlled studies because they require more participants and are more challenging to execute correctly.
Some trials test multiple doses of a new treatment against a placebo. Each of the groups receiving the same treatment (or placebo) is called an arm. A three-arm study could compare a high and low dose of treatment to placebo, while a single-arm study would track certain criteria (e.g. blood pressure) in a treatment group over time. Whatever study design is decided upon, the goal is to provide the groups who approve new treatments with clear and accurate information about how the new treatment performs in improving the lives of patients.
References
Wang S. Clinical Trials: Foundation for Medical Advancement. MedReport Foundation. Published October 30, 2024. Accessed October 13, 2025. https://www.medreport.foundation/post/clinical-trials-foundation-for-medical-advancement
FDA. Step 3: Clinical Research. U.S. Food and Drug Administration. Published January 4, 2018. https://www.fda.gov/patients/drug-development-process/step-3-clinical-research
Nair B. Clinical Trial Designs. Indian Dermatology Online Journal. 2019;10(2):193-201. doi:https://doi.org/10.4103/idoj.IDOJ_475_18
An Introduction to Clinical Trials: Design Issues.; 2013. https://ictr.johnshopkins.edu/wp-content/uploads/2013/07/7.19.13.Miller-Clinical-Trials.pdf
Streiner DL. Alternatives to placebo-controlled Trials. The Canadian Journal of Neurological Sciences Le Journal Canadien Des Sciences Neurologiques. 2007;34 Suppl 1:S37-41. doi:https://doi.org/10.1017/s0317167100005540
Evans SR. Clinical Trial Structures. Journal of experimental stroke & translational medicine. 2010;3(1):8-18. doi:https://doi.org/10.6030/1939-067x-3.1.8
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