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Blinding (Masking) and the Placebo Effect

Blinding (Masking) and the Placebo Effect

James Brian Byrd, MD, MS, FAHA, FACC

University of Michigan Medical School



03 March 2016

Clinical studies provide the platform for testing new treatments to improve patient care. The careful design and interpretation of clinical studies is central to ensuring that the specific effect of a treatment is identified. However, the placebo effect can complicate the interpretation of clinical studies. The placebo effect is a beneficial effect that cannot be attributed to the active components of a specific drug. Instead, the placebo effect has traditionally been thought to be due to the patient's perception that the drug is helpful. A placebo effect on blood pressure (BP) is reported in some studies but not others, and fundamental questions about the placebo effect on BP remain unresolved.

There is renewed interest in the placebo effect, in particular whether it occurs when patients are aware they are taking a placebo: “placebo effect without deception” (N Engl J Med 2015; 373:8-9). In a small study, Kaptchuk et al. (PLoS ONE 2010; 5(12): e15591), investigated placebo treatment without deception in patients with irritable bowel syndrome. The investigators found evidence for an effect of placebo compared to no treatment, even when patients knew they were taking an inactive treatment. This finding calls into question the traditional understanding of the placebo and warrants additional investigation.

Randomized clinical trials typically begin with a “run-in phase,” during which patients are given a placebo, or sometimes active drug. In rare instances, the patient is told that the pill given during the run-in phase of the study is a placebo and is inactive. Patients in such studies are later randomly assigned to receive treatment with active drug or placebo—but they are typically not told which treatment they have been given during this next phase of the study (“blind placebo”). Thus, some clinical trial participants transition from knowing they are taking a placebo to not knowing, but are still taking a placebo within the same study. This is referred to as an “open-label” run-in design and provides an opportunity to assess whether patients’ awareness of taking a placebo modifies the effect of placebo on BP.
Understanding the intricacies of the placebo effect will offer insight into how the presentation of a treatment can influence the effectiveness of that treatment.

Aim. To compare BP at the end of open-label run-in to BP during blind placebo treatment.

We propose to re-analyze data from Boehringer-Ingelheim’s “12-Week Efficacy and Safety Study of Empagliflozin (BI 100773) in Hypertensive Patients with Type 2 Diabetes Mellitus.” We will compare BP at the end of the open-label run-in phase to BP during blind placebo in participants randomized to placebo. Excellent measurements using best practices were made at both time points, making this analysis feasible. We anticipate publishing our results in distinguished peer-review journals and presenting our results at international scientific conferences.

[{ "PostingID": 2513, "Title": "BI-1245.48", "Description": "12 Week Efficacy and Safety Study of Empagliflozin (BI 10773) in Hypertensive Patients With Type 2 Diabetes Mellitus

Medicine: empagliflozin, Condition: Diabetes Mellitus, Type 2; Hypertension, Phase: 3, Clinical Study ID: 1245.48, Sponsor: Boehringer Ingelheim" }]

Statistical Analysis Plan

The publication citation will be added after the research is published.