INTRODUCTION: There is no effective treatment for geographic atrophy (GA). To help design future GA treatment trials, we conducted a meta-analysis for GA growth rate and its variability in natural history studies. METHODS: Literatures were searched up to April 30, 2020. Data were extracted independently by 2 authors and analyzed using random-effects models. RESULTS: The pooled mean GA growth rate was 1.66 mm2/year (SD=1.27 mm2/year, I2=97.0%, p<0.001) from 23 studies (3078 patients) reported with growth rate in mm2/year and 0.33 mm/year (SD=0.17 mm/year, I2=83.0%, p<0.001) from 12 studies (1808 patients) reported with growth rate in mm/year. Larger mean baseline GA area in mm2 was associated with larger mean growth rate in both mm2/year and mm/year (p<0.001). The sample size at 85% power for detecting 15% reduction in growth rate in a two-arm GA trial is 464 and 209 patients per arm respectively for using mm2/year and mm/year as the primary outcome. DISCUSSION/ CONCLUSION: GA natural history studies had pooled mean (SD) GA growth rate of 1.66 (1.27) mm2/year or 0.33 (0.17) mm/year. Because GA growth rate using mm/year requires smaller sample size than using mm2/year, GA growth rate in mm/year is recommended as the primary outcome measure for future GA trials.
INTRODUCTION: There is no effective treatment for geographic atrophy (GA). To help design future GA treatment trials, we conducted a meta-analysis for GA growth rate and its variability in natural history studies. METHODS: Literatures were searched up to April 30, 2020. Data were extracted independently by 2 authors and analyzed using random-effects models. RESULTS: The pooled mean GA growth rate was 1.66 mm2/year (SD=1.27 mm2/year, I2=97.0%, p<0.001) from 23 studies (3078 patients) reported with growth rate in mm2/year and 0.33 mm/year (SD=0.17 mm/year, I2=83.0%, p<0.001) from 12 studies (1808 patients) reported with growth rate in mm/year. Larger mean baseline GA area in mm2 was associated with larger mean growth rate in both mm2/year and mm/year (p<0.001). The sample size at 85% power for detecting 15% reduction in growth rate in a two-arm GA trial is 464 and 209 patients per arm respectively for using mm2/year and mm/year as the primary outcome. DISCUSSION/ CONCLUSION: GA natural history studies had pooled mean (SD) GA growth rate of 1.66 (1.27) mm2/year or 0.33 (0.17) mm/year. Because GA growth rate using mm/year requires smaller sample size than using mm2/year, GA growth rate in mm/year is recommended as the primary outcome measure for future GA trials.