Thyroid Disease Is Associated with Higher Age-Related Macular Degeneration Risk: Results from a Meta-Analysis of Epidemiologic Studies

Abstract

Background: Although epidemiologic studies have suggested that thyroid disease may be a risk factor for age-related macular degeneration (AMD), this finding is still controversial. Objectives: The aim of this meta-analysis was to investigate whether an association exists between thyroid disease and medication and AMD in epidemiologic studies. Methods: We searched PubMed, EMBASE, and Google Scholar from their inception to March 2020 for cross-sectional, case-control, and cohort studies that assessed thyroid function and AMD risk. Data from selected studies were extracted, and a meta-analysis was performed using fixed-effects or random-effects models. The statistical heterogeneity (I2) among studies and the possibility of publication bias were evaluated. If I2 >50%, a significant heterogeneity existed among studies, and a random-effects model was used to calculate the pooled RR. Otherwise, a fixed-effects model was performed. Results: A total of 13 epidemiologic studies that consisted of 7 thyroid disease and 7 thyroid medication studies were included. Statistically significant heterogeneity was observed in the study results (I2thyroid disease = 80.1%; I2thyroid medication = 69.0%). A significant positive association was found between thyroid disease and AMD, with an overall relative risk (RR) of 1.25 (95% CI: 1.02, 1.54). However, there was no statistical association between thyroid medication and AMD risk (pooled RR 1.26 [95% CI: 0.92-1.72]). Egger's test indicated that there was no significant publication bias for thyroid disease (p = 0.889) or thyroid medication (p = 0.226). Conclusions: Our findings indicate that thyroid disease is associated with higher AMD risk. Thyroid disease prevention strategies may have a significant effect on the prevention of AMD and warrant further evaluation.