Incidence of and Risk Factors Associated With Age-Related Macular Degeneration: Four-Year Follow-up From the ALIENOR Study

Abstract

Importance: While the prevalence of age-related macular degeneration (AMD) differs according to continents and races/ethnicities, its incidence in the European continent has been scarcely documented.

Objective: To describe the incidence and associated risk factors of AMD in elderly French individuals.

Design, setting, and participants: This population-based cohort study of 963 residents of Bordeaux, France, who were 73 years or older at baseline and participated in the Antioxydants, Lipides Essentiels, Nutrition et Maladies Oculaires (ALIENOR) Study between October 2, 2006, and December 21, 2012. Of 829 participants at risk for incident AMD, 659 (79.5%) were observed for a mean (SD) duration of 3.8 (1.1) years. Data were analyzed from August 2016 to March 2017.

Main outcomes and measures: Age-related macular degeneration was graded from retinal photographs and spectral-domain optical coherence tomography into 5 exclusive stages: no AMD, early AMD1, early AMD2, late atrophic AMD, and late neovascular AMD.

Results: Of the 659 eligible participants, 413 (62.7%) were women, and the mean (SD; range) age was 79.7 (4.4; 73-94) years. A total of 120 incident cases of early AMD and 45 incident cases of advanced AMD were recorded. Incidence rates of early and advanced AMD were 79.9 (95% CI, 66.8-95.5) per 1000 person-years and 18.6 (95% CI, 13.9-24.9) per 1000 person-years, respectively, corresponding to 5-year risks of 32.9% and 8.9%. Incidence of advanced AMD per 1000 eye-years was 1.5 in eyes without any AMD at baseline, 42.4 in those with early AMD1, and 85.1 in those with early AMD2. In multivariate analysis without correction for multiple testing, progression from early to advanced AMD was associated with AMD grade in the fellow eye (hazard ratio [HR] according to grade, 13.0 [95% CI, 2.8-61.2] to 22.5 [95% CI, 2.6-195.9]), having smoked at least 20 pack-years (calculated as number of smoking years × mean number of cigarettes per day / 20; HR, 3.0; 95% CI, 1.4-6.5), and complement factor H (CFH) Y402H genotype (CC genotype: HR, 2.3; 95% CI, 1.0-5.3; TC genotype: HR, 1.5; 95% CI, 0.6-3.7). Incidence of early AMD was associated with early AMD in the fellow eye (early AMD1: HR, 2.6; 95% CI, 1.6-4.2; early AMD2: HR, 5.6; 95% CI, 3.3-9.4) and high plasma high-density lipoprotein cholesterol levels (HR, 1.2; 95% CI, 1.0-1.4).

Conclusions and relevance: In this cohort, AMD incidence rates were similar to those observed in other European populations. This study suggests a high risk for incident early AMD in individuals with high plasma high-density lipoprotein cholesterol levels while confirming the high risk for progression from early to advanced AMD in heavy smokers and carriers of CFH Y402H at-risk genotypes.

Figure.. Eye-Specific Incidence of Age-Related Macular Degeneration (AMD) According to Age Group and AMD Grade at Baseline

Incidence of advanced AMD calculated as number of cases per 1000 eye-years. Early AMD1 defined as presence of soft distinct drusen without pigmentary abnormalities or of pigmentary abnormalities without large drusen (>125 μm). Early AMD2 defined as presence of soft indistinct drusen and/or reticular pseudodrusen and/or soft distinct drusen associated with pigmentary abnormalities (hyperpigmentation or hypopigmentation). The error bars indicate 95% CIs.