Association of neovascular age-related macular degeneration with month and season of birth in Italy

In order to investigate the influence of season and month of birth on the risk of neovascular age-related macular degeneration (n-AMD) in Italy, we evaluated the month birth and sex of all patients, recorded in the anti-vascular endothelial growth factor (VEGF) monitoring registry of the Italian Medicines Agency, born between 1925-1944, who received intravitreal anti-VEGF injections for n-AMD between January 1, 2013 and July 29, 2015. The numbers of all births in Italy in the same years, extracted from the Italian National Institute of Statistics, were used to calculate the expected number of n-AMD cases. Overall, 45,845 patients (19,207 men, 26,638 women) received intravitreal anti-VEGF for n-AMD; in the same years, 20,140,426 people (10,334,262 male, 9,806,164 female) were born in Italy. Comparing the observed number of n-AMD cases with the expected number of n-AMD cases in each season, we found that the season-specific risk for n-AMD was 2.5% higher for those born in summer (OR= 1.03, Bonferroni-corrected P= 0.008) and 3% lower for those born in winter (OR= 0.96, Bonferroni-corrected P= 0.0004). When considering the month of birth, the risk of n-AMD was 5.9% lower for people born in January (OR= 0.93, Bonferroni-corrected P= 0.0012). The factors causing such differences should be determined.