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February 1989

Effect of Investigator Bias on Clinical Trials

Author Affiliations

From the Department of Dermatology, University of Texas Medical Branch, Galveston.

Arch Dermatol. 1989;125(2):216-218. doi:10.1001/archderm.1989.01670140068011

• Two clinical trials were performed to determine the relative efficacy of tioconazole, a new antifungal agent for treating patients with tinea pedis. One study compared the new agent with a placebo cream and the other with miconazole nitrate, an established effective antifungal agent. The investigators found a much higher "cure" rate for tioconazole when both treatment groups were known to receive active agents than the cure rate for tioconazole found in the placebo-controlled study. These results showed that the expectations of investigators can influence their clinical evaluations. Such bias could also influence the results of clinical trials.

(Arch Dermatol 1989;125:216-218)