Objective: To compare 2-year changes from baseline scores on the National Eye Institute Visual Function Questionnaire (NEI-VFQ) between similar participants assigned to sham and no-treatment control arms in randomized clinical trials of treatment of subfoveal choroidal neovascularization secondary to age-related macular degeneration.
Methods: We retrospectively matched sham controls from a randomized trial to no-treatment controls (no sham or placebo) from another trial on 7 baseline prognostic criteria. Two-year changes in overall and subscale scores were compared using data from those who had 2-year interviews and also using the last follow-up observation carried forward to impute missing 2-year interview scores.
Results: A match to a no-treatment control on all 7 criteria was identified for 62 of 238 sham controls. Among the 42 matched pairs of controls interviewed at 2 years, no important difference in 2-year change in NEI-VFQ scores overall or by subscale was observed. Findings were similar for the 56 matched pairs of controls who could be analyzed for 2-year changes in scores using the method of last follow-up observation carried forward.
Conclusions: Findings from this retrospective matched-pairs analysis suggest that sham treatment to mask patient participants in clinical trials may be unnecessary when patient-reported outcomes are of interest and standard instruments are administered by interviewers masked to treatment assignment. This analysis, together with our earlier analysis of visual acuity outcomes, questions the necessity for sham (placebo) controls in randomized clinical trials in ophthalmology when other methods to minimize outcome assessment bias are incorporated into the design.
Trial registration: ClinicalTrials.gov NCT00000150 NCT00056836.