Blinding in Placebo-Controlled Trials
June 2001
in “
Annals of Internal Medicine
”
TLDR The conclusion suggests that the zinc lozenge study is valid despite imperfect blinding, as many participants could not correctly identify their lozenge type.
The document contains letters discussing medical research and ethics, including a critique of "distant healing" studies and the importance of blinding in placebo-controlled trials. Ananda S. Prasad, MD, PhD, defends a study on the efficacy of zinc lozenges in treating the common cold, which involved 20 healthy volunteers. Despite concerns about the blinding due to minor differences between the zinc and placebo lozenges, 52% of the zinc group and 74% of the placebo group could not correctly identify their lozenge type, suggesting that the blinding may have been sufficiently maintained. Prasad argues that the study's results, which showed zinc lozenges reduced the duration and severity of cold symptoms, are valid even if the blinding was not perfect. Other letters in the document address the application of ethical principles in health care.
