Abstract
Purpose :
Seasonal variation has been reported in the incidence and mortality of various systemic diseases, including cerebrovascular and cardiovascular disease. Small studies have proposed a similar effect for AMD. However, no large-scale study examined this variation in neovascular age-related macular degeneration (AMD). We investigated a possible correlation between seasonality and the first treatment for neovascular age-related macular degeneration in large-scale real-life data. Based on the previous studies, we hypothesized that there might be fewer new presentations of nvAMD in summer months.
Methods :
Retrospective cross-sectional study on electronic medical records obtained from 27 sites over 4 years (2014-2017). We filtered the data for first intravitreal injections of any Anti-VEGF type per patient, to treat neovascular AMD. Local protocols aimed to treat within 14 days after the diagnosis of neovascular AMD. We compared the number of occurrences in summer months (May-October) with those in winter months (November-April). Patients were divided into 2/4 groups based on the season at which their first injection was given: A general linear mixed model was used to estimate incidence rate ratios, with sites as random effects. A p-value < 0.05 was considered as significant.
Results :
A total of 22,714 patients were included in the study, with a mean age of 84.1 years. Overall 5,636 patients had a first injection in spring, 5,817 in summer, 6,009 in autumn, and 5,252 in winter. There were more injections in summer than in winter (p <0.001). When modeling each season, there were more injections in each season compared to winter (p<0.001).
Conclusions :
We found a lower incidence of first treatments for neovascular AMD in winter months and a higher incidence in summer, contradicting previous reports.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.