Improving Efficiency in Geographic Atrophy Clinical Trials Using Run-In Phases or Single-Arm Designs

For geographic atrophy (GA) investigations, do run-in phases within randomized clinical trials (RCTs) or using single-arm trials lead to decreased sample size requirements?Per the results of this diagnostic/prognostic study, for 2-year RCTs with 90% power to detect a 25% effect on slowing change in square root GA area over time, sample sizes were 156 for an RCT vs 82, 40, or 26 for RCTs with run-in phases of 3, 6, or 9 months, respectively. The sample size required for 2-year single-arm trials was 14.Incorporating run-in phases into RCTs or single-arm designs might improve efficiency of GA clinical trials by exploiting the inherent stability of GA enlargement rates.

Corresponding Author: Tiarnán D. L. Keenan, BM BCh, PhD, Division of Epidemiology and Clinical Applications, National Eye Institute, National Institutes of Health, 10 Center Dr, Bldg 10, CRC, Room 10D45, MSC 1204, Bethesda, MD 20892-1204 (tiarnan.keenan@nih.gov).

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