Validating the AREDS Simplified Severity Scale of Age-Related Macular Degeneration with 5- and 10-Year Incident Data in a Population-Based Sample

Abstract

Purpose: Most classification systems for age-related macular degeneration (AMD) were developed from patients in clinical trials. We aimed to validate the Age-Related Eye Diseases Study (AREDS) simplified severity scale of AMD classification using 5- and 10-year incident late AMD data from the population-based Blue Mountains Eye Study (BMES) cohort.

Design: Comparative study of population-based cohort and clinical trial.

Participants: Blue Mountains Eye Study participants 40 to 97 years of age at baseline (n = 2134) and AREDS participants 55 to 80 years of age (n = 3640).

Methods: In the BMES, AMD lesions were graded from stereoscopic color photographs and were classified according to the AREDS simplified severity scale. The AREDS simplified scale calculates a risk score based on the number of early AMD risk factors (large drusen and pigment abnormalities) in both eyes that can range from 0 to 4.

Main outcome measures: Five- and 10-year incident late AMD (presence of geographic atrophy or choroidal neovascularization).

Results: The AREDS simplified scale performed similarly when applied to both the BMES population-based participants and the AREDS clinical trial-based participants in predicting 5- and 10-year incidence of late AMD. For scores 0 to 4, the 5-year incidence rates for the BMES compared with the AREDS were 0.2% versus 0.4%, 3.1% versus 3.1%, 12.1% versus 11.8%, 13.5% versus 25.9%, and 47.1% versus 47.3%, respectively. The corresponding 10-year incidence rates for the BMES compared with the AREDS were 0.7% versus 1.5%, 7.3% versus 8.4%, 36.6% versus 27.6%, 20.0% versus 52.7%, and 75.0% versus 71.4%, respectively.

Conclusions: The AREDS simplified severity scale classified late AMD risk levels similarly when applied to population-based and clinical trial samples. These results support the robustness of the AREDS simplified severity scale.