Placebo therapy program shows potential effectiveness in future clinical trials

Invest Ophthalmol Vis Sci. 2009;50:2560-2566.

A placebo therapy program effectively maintained patient masking and showed potential utility for future clinical trials, according to a study.

Investigators evaluated the Convergence Insufficiency Treatment Trial placebo therapy program in maintaining masking of patients randomized to office-based treatment arms. They assessed whether demographic variables affected masking and whether the perception of the assigned treatment group affected outcomes or adherence to treatment.

The study included 221 patients ages 9 to 17 years randomized to four treatment groups; 114 patients in two of the groups were office-based and masked from treatment.

"The placebo therapy program was designed to appear to be real vergence/accommodative therapy, without stimulating vergence, accommodation or fine saccades (beyond levels of daily visual activities," the study authors said. "After treatment, patients in the office-based groups were asked whether they thought they had received real or placebo therapy and how confident they were in their answers."

Study data showed that 93% of patients assigned to real therapy and 85% assigned to placebo therapy believed they were in the real therapy group (P = .017). Results showed no significant difference between the groups' adherence to therapy. The percentage of patients who believed they were assigned to real therapy did not differ by age, gender, race or ethnicity.

"Masking was not affected by demographic variables," the authors said. "Perception of group assignment was not related to symptoms or signs at outcome."