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The Importance of Outcome Measure Research in Stargardt Disease.

In this issue of JAMA Ophthalmology, the 2 articles from the Natural History of the Progression of Atrophy Secondary to Stargardt Disease (ProgStar) Study 1,2 focus on outcome measure research in Stargardt disease. Nearly 20 years ago, ABCA4 was identified as a causative gene for Stargardt disease 3 and its role in photoreceptor function elucidated, leading to potential approaches to intervene clinically on this disease. Critical to the design and success of any interventional study is knowledge about the functional and anatomic parameters defining the disease and information on their rate of change. Based on carefully obtained natural history information, outcome variables can be chosen for a clinical trial of a potential new treatment and study duration and sample size can be calculated. ProgStar has been designed to follow up a large number of ABCA4-genotyped patients in a multimodal natural history study. The hope is that these natural history data can be used to develop the reproducible outcome variables that will be critical for use in clinical trials of new treatments for Stargardt disease. The outcome key outcomes of clinical trial design disease and following its progression. Several groups have demonstrated longitudinal changes in fundus autofluorescence in Stargardt disease. Quantitating these changes in autofluorescence to include growth of atrophic lesions as well as changes in flecks and background fluorescence could become a key outcome measure in clinical trials because they are noninvasive in vivo biomarkers for disease pathogenesis.