Patients of European descent have the highest annual incidence of early and late age-related macular degeneration (AMD), according to a new study in the British Journal of Ophthalmology.
The analysis offers an up-to-date view of AMD globally and reveals that pooled global annual incidences of early and late AMD are 1.59% (95% CI 1.12% to 2.10%) and 0.19% (95% CI: 0.13% to 0.28%), respectively. People of European descent have the highest incidence of early (2.73%, 95% CI 1.63% to 4.57%) and late (0.36%, 95% CI 0.17% to 0.75%) AMD of the ethnic groups surveyed.
The study reveals the incidence of late AMD is higher in Europe (0.26%, 95% CI 0.17% to 0.45%) than in other regions, while the lowest incidence of early AMD is in Asia (1.02%, 95% CI 0.81% to 1.29%). After Caucasians, Black patients have the highest incidence of early AMD (1.73%, 95% CI 0.93% to 3.21%), followed by Asians (0.93%, 95% CI 0.72% to 1.19%).
The researchers add that their findings are consistent with previous studies that show the annual incidence of late AMD was 0.35% in American Caucasians and 0.14% in European Caucasians.
The high incidence of early AMD in Africa (2.85%, 95% CI 2.46% to 3.32%) might be a result of higher ultraviolet (UV) radiation exposure, stronger genetic predisposition or a greater susceptibility to inflammation. However, limited studies were conducted on the continent and this interpretation isn’t conclusive.
Researchers analyzed 24 studies related to AMD published before September 2019. Studies were included if they were original research reports describing incidence of AMD or were full-text reviews that met a number of criteria, such as using a standardized photographic assessment of AMD, surveying patients from a clearly defined geographic area and including at least 100 people at baseline.
Early AMD was defined as the presence of large indistinct soft drusen, reticular drusen or the copresence of large distinct soft drusen and retinal pigmentary abnormalities within the macula, in the absence of any late AMD lesions.
Late AMD was defined as the presence of neovascular AMD, indicated by retinal pigment epithelial or neurosensory subretinal detachment, retinal or subretinal hemorrhage, subretinal fibrosis or old atrophic disciform scars, or photocoagulation scars with a history of neovascular AMD, or the presence of pure geographic atrophy within the macula.
Researchers looked at incidence of both early and late AMD among four ethnic groups: Caucasian, Black, Hispanic and Asian. The average baseline age was older than 55.
Few studies have examined the incidence of AMD in non-Western countries and non-Caucasian ethnic groups. Macular degeneration is a leading cause of visual impairment and although injections have improved treatment, their cost means they aren’t accessible to everyone, especially patients in developing countries.
Understanding geographic patterns and distributions of AMD would help physicians who are developing strategies for care and public health measures worldwide.
Zhou M, Duan P, Liang J, Zhang X, Pan C. Geographic distributions of age-related macular degeneration incidence: a systematic review and meta-analysis. Br J Ophthalmol. Published online September 9, 2020. doi:.10.1136/BJOPHTHALMOL-2020-316820