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Quoc Ho, Mia Mackowski, Kevin Kerr, Francisco J Lopez, Susan Schneider; Comparison of Three Baseline Measures to Predict Geographic Atrophy Progression Rate in Clinical Studies. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2343.
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© ARVO (1962-2015); The Authors (2016-present)
Baseline geographic atrophy (GA) area has been shown to correlate with GA progression rate. The GA Circularity Index (GACI), an indicator of lesion shape irregularity calculated as the ratio of lesion area and the area of the circle defined by the lesion perimeter, has also been reported to predict lesion progression rate. The predictive value of baseline perimeter as an alternative measure of progression rate has not been reported to date. In addition, the rank order of predictive value for these baseline measures has not been evaluated. The objective of this study was to assess and compare GA baseline area, GACI, and perimeter as predictors of lesion progression rate.
To evaluate the natural course of GA progression, data from GA subjects in the sham-procedure group (n=19) from a phase 2a Allergan study (NCT00658619) were used. Color fundus photographs with superimposed GA lesion tracings were obtained from the study archive and reanalyzed with ImageJ software (v1.50i). GACI and perimeter were quantified for 19 eyes from 19 GA subjects, and matched with previously reported GA data. Using R software (v3.3.2) under R Studio, matrix correlations were conducted to assess GA progression rate at Year 1 and 2 as a function of GA baseline area, GACI and perimeter.
Mean baseline area, GACI, and perimeter [means (range)] were 14.04 (1.65-48.34) mm2, 0.33 (0.07-0.85), and 21.88 (4.15-60.72) mm, respectively. Baseline area and perimeter demonstrated statistically significant associations with GA progression rate at Year 1 (r2=0.685; p<0.001 and 0.560; p<0.013, respectively), while GACI association with GA progression rate was poor (r2=-0.089; p<0.72). Associations at Year 2 followed the same trends.
Results from this analysis were consistent with established data that showed an association between baseline GA area and lesion progression rate. However, no statistically significant association between GACI and lesion progression rate was shown. On the other hand, our analysis demonstrated strong correlation between baseline GA perimeter and lesion progression rate. The relative ranking of predictive value for baseline measures on lesion progression rate were GA area > perimeter > GACI. Further studies using larger study populations are warranted to confirm the role of these baseline measures to predict the natural course of GA progression.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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