Age‐related macular degeneration in Portugal: prevalence and risk factors in a coastal and an inland town. The Coimbra Eye Study – Report 2

Abstract

ABSTRACT.Purpose: To determine the age-and sex-specific prevalence of early and late age-related macular degeneration (AMD) in two Portuguese population-based samples and to identify its risk factors. Population: A population of 6023 adults aged ≥55 years was recruited from two Portuguese primary healthcare units in the central region of Portugal -one from a coastal (n = 3000) and another from an inland town (n = 3023). Methods: Cross-sectional population-based study. Participants were enrolled in the two locations between August 2009 and October 2013. Responders underwent standardized interviews and ophthalmologic examination, including digital fundus imaging. All fundus photographs were graded according to an International Classification and Grading System. The main outcome measures consisted of age-and sex-adjusted prevalence of early and late AMD. Potential epidemiologic risk factors were also evaluated using logistic regression analysis. Results: Of the 6023 subjects enrolled, 5996 had gradable fundus images and were included in the analysis. The crude prevalence of early and late AMD was 6.99 and 0.67%, respectively, for the coastal town and 15.39 and 1.29% for the inland town. Age-and sex-adjusted prevalence of any AMD for the Portuguese population was 12.48% (95% CI: 11.61-13.33) with late AMD accounting for 1.16% (95% CI: 0.85-1.46). Neovascular AMD (NV-AMD) and geographic atrophy (GA) accounted for 0.55% (95% CI: 0.36-0.75) and 0.61% (95% CI: 0.37-0.84) of individuals, respectively. After adjusting for possible confounding factors, prevalence of early and late AMD increased with increasing age (OR = 1.35; 95% CI: 1.23-1.49 for early and OR = 3.01; 95% CI: 2.22-4.08 for late AMD, per each decade of age increase, p < 0.001). After adjustment for age, sex, family history, smoking history, hypertension, diabetes and BMI, subjects from the inland town presented a significantly higher OR of early and late AMD than subjects from the coastal town (OR = 2.57, 95% CI: 2.12-3.12, p < 0.001 for early and OR = 2.06, 95% CI: 1.07-3.95, p = 0.029 for late AMD). Conclusions: The prevalence of early and late AMD in this Portuguese population was similar to other large-scale population-based cohorts. After controlling for confounders, age and study site of inclusion were significant independent predictors for both early and late forms of the disease. Further analysis will be needed to completely unravel the underlying reasons for this difference regarding geographic location.

Incidence of Age-Related Macular Degeneration in the Central Region of Portugal: The Coimbra Eye Study – Report 5

“…Information on the identification and description of the baseline study population has appeared in previous reports [20, 23]. Briefly, the Epidemiologic Coimbra Eye Study is a single-center population-based study whose cohort included two geographically distinct Portuguese populations aged ≥55 years: one from a coastal town (Mira) and the second from an inland town (Lousã), both in the central region of Portugal.…”

“…performed a differential analysis and graded the suspected AMD cases using the International Classification and Grading System [24]. Differential grading was performed by grading CFP images alone to allow for comparability with our previous prevalence study of AMD in this population, whose grading was based on CFP only [20, 23]. CFP image quality was adjusted using color balance software, an algorithm developed to automatically standardize the brightness, contrast and color balance of digital color fundus photographs in AMD grading [25].…”

“…Our group previously reported on AMD prevalence in a coastal town and in an inland town of the central region of Portugal [20, 23]. Globally, the prevalence of early and late AMD in Portugal was found to be comparable to other Western and Asian countries [20].…”

“…These countries are known to have distinct sociocultural and economic aspects. For example, subjects from these countries mostly follow a Mediterranean diet, with higher consumption of fish, fruit and vegetables, compared to northern European countries (OECD 2012) [20], and these environmental factors may impact AMD prevalence and incidence [20-22]. …”

“…Globally, the prevalence of early and late AMD in Portugal was found to be comparable to other Western and Asian countries [20]. In the subanalysis of the coastal town the early forms of the disease had a similar prevalence to that of other large-scale population-based cohorts, but late AMD was less frequent [23].…”