Researchers at the Scheie Eye Institute, University of Pennsylvania, Philadelphia, has published a systematic review to assess the key design characteristics of geographic atrophy (GA) clinical trials, identified in the ClinicalTrials.gov database. In the analysis, the studies comprised a large variation in the design characteristics of the treatment trials. The most common primary outcome measure was for atrophy growth, while visual acuity (VA) is the most common secondary outcome. As there is no effective treatment for geographic atrophy, secondary to age-related macular degeneration, there is a significant demand to develop new treatments for GA. While it is clear that anti-VEGF treatments for AMD has been relatively successful, the GA population has not yet developed a clear medical success.
In the systematic review, design characteristics in the study include eligibility criteria, sample size, length of follow-up, and primary and secondary outcomes. According to the analysis there are among 53 registered GA treatment trials, 10 (19%) were in phase 1, 36 (68%) in phase 1-2 or 2 (phase 2), and 7 (13%) in phase 2-3 or 3 (phase 3); 24 of the 53 trials (45%) are ongoing. The data indicates that the most common interventions were anti-inflammatory agents (40%). GA growth was used as the primary outcome in 58% of phase 2 trials and 71% of phase 3 trials, and as a secondary outcome in 31% of phase 2 trials and 0% of phase 3 trials. Visual acuity was used as the primary outcome in 17% of phase 2 trials and 14% of phase 3 trials, and as a secondary outcome in 67% of phase 2 trials and 57% of phase 3 trials. According to the research studies, the median sample size of trials was 22 in phase 1, 60 in phase 2, and 772 in phase 3, with median follow-up length of 0.7, 1.0, and 2.0 years, respectively. The study eye baseline VA criterion was specified in 33 trials (62%) and varied across trials, with a lower limit of 20/50 to 20/400. The criterion for baseline GA size was specified in 14 trials (26%), with minimum GA size 0.5 to 1 disc area.
Notwithstanding the primary and secondary outcomes to identify these traditional measures, it is also crucial for clinical researchers to collect active patient reporting outcome measures. While objective measurements will continue as a gold-standard for trial activity, the methodological analyses and innovative questionnaires will evolve over the coming years.