Abstract
IMPORTANCE: The Age-Related Eye Disease Study age-related macular degeneration (AREDS AMD) scale is designed to classify AMD severity. The present cohort study explored whether 2-year progression along this scale was useful for estimating the risk of future progression to late AMD or best-corrected visual acuity (BCVA) loss. OBJECTIVE: To assess whether 2-year progression along the AREDS AMD scale can be used to estimate the probability of long-term clinically meaningful outcome measures for clinical trials or epidemiologic studies. DESIGN, SETTING, AND PARTICIPANTS: Age-Related Eye Disease Study participants enrolled in a clinical trial of oral micronutrient supplements had annual color fundus photographs graded centrally using the AREDS AMD scale. Two-year progression (≥2-step and ≥3-step increases in AMD score between baseline and the 2-year study visit) was evaluated as a method of estimating the risk of long-term progression to late AMD or BCVA loss. The AREDS (1992-2001) was a randomized, placebo-controlled clinical trial based at 11 retinal specialty clinics in the United States. The dates of analysis in the present cohort study were November 1992 through November 2005. MAIN OUTCOMES AND MEASURES: Development of neovascular (NV) AMD, central geographic atrophy (CGA), any geographic atrophy (GA), or BCVA loss of at least 2 lines or at least 3 lines. RESULTS: Among 3868 participants in the AREDS free of late AMD at baseline, the mean (SD) age was 68.3 (5.0) years, and 2180 of 3868 (56.4%) were women. In the first 2 years after randomization to the AREDS, 669 of 7458 (9.0%) of eyes had at least 2-step 2-year progression, and 275 of 7458 (3.7%) of eyes had at least 3-step 2-year progression. In the 5-year follow-up period (years 2-7), 486 of 7223 (6.7%) of eyes developed NV AMD, 339 of 7253 (4.7%) developed CGA, 726 of 7246 (10.0%) developed any GA, 2622 of 7095 (37.0%) had at least 2-line BCVA loss, and 1494 of 7155 (20.9%) had at least 3-line BCVA loss. After adjusting for demographic and clinical confounders and stratifying by baseline AMD score, statistically significant associations were observed between at least 2-step and at least 3-step 2-year progression of AMD score and subsequent 5-year development of NV AMD: hazard ratios (HRs) ranged from 3.6 (99% CI, 2.4-5.2) to 19.4 (99% CI, 7.7-48.9). For CGA, HRs ranged from 2.6 (99% CI, 1.7-4.0) to 4.7 (99% CI, 2.5-8.9); the results were similar for any GA. For at least 2-line and at least 3-line BCVA loss, HRs ranged from 1.3 (99% CI, 1.0-1.7) to 2.8 (99% CI, 1.8-4.3). For all outcomes, at least 3-step 2-year progression had stronger associations than at least 2-step 2-year progression. These findings were also validated in the AREDS2 cohort. CONCLUSIONS AND RELEVANCE: Two-year progression of AMD score was associated with progression to clinically meaningful anatomic (late AMD) and vision (≥2-line or ≥3-line loss) outcomes, suggesting that this scale may be useful for future clinical trials designed to slow the progression of AMD.