To describe risk factors for geographic atrophy (GA) in the Comparison of Age-related Macular Degeneration Treatments Trials (CATT), this cohort within a randomized clinical trial analyzed 1,024 CATT patients with no GA visible on color fundus photographs (CFPs) and/or fluorescein angiograms (FAs) at enrollment..
Eyes were assigned to ranibizumab (0.5 mg) or bevacizumab (1.25 mg) treatment and to a two-year monthly or pro re nata
(p.r.n.) injection regimen, or monthly injections for one year and p.r.n. for one year. Demographic, genetic and baseline ocular characteristics and lesion features of CFP/FA and optical coherence tomography (OCT) were evaluated as risk factors for GA through two years of follow-up. Time-dependent Cox proportional hazard models were used to estimate adjusted hazard ratios (aHRs). Development of GA was the main outcome measure.
By two years, GA developed in 187 of 1,024 patients (18.3%). Baseline risk factors for GA development included baseline visual acuity (VA) ≤20/200 (aHR, 2.65; 95% confidence interval [CI], 1.43 to 4.93), retinal angiomatous proliferation (RAP; aHR, 1.69; 95% CI, 1.16 to 2.47), GA in the fellow eye (aHR, 2.07; 95% CI, 1.40 to 3.08) and intraretinal fluid at the foveal center (aHR, 2.10; 95% CI, 1.34 to 3.31). Baseline factors associated with lower risk for GA development included blocked fluorescence (aHR, 0.49; 95% CI, 0.29 to 0.82), OCT measurements of subretinal fluid thickness of >25 µ (aHR, 0.52; 95% CI, 0.35 to 0.78), subretinal tissue complex thickness of >275 compared with ≤75 µ (aHR, 0.31; 95% CI, 0.19 to 0.50) and vitreomacular attachment (aHR, 0.55; 95% CI, 0.31 to 0.97). Ranibizumab compared with bevacizumab had a higher risk (aHR, 1.43; 95% CI, 1.06 to 1.93), and monthly dosing had a higher risk (aHR, 1.59; 95% CI, 1.17 to 2.16) than p.r.n. dosing. There were no strong associations between development of GA and the presence of risk alleles for CFH, ARMS 2, HTRA1, C3 or TLR3.