Abstract
Purpose:
The risk of age-related macular degeneration (AMD) has been reported to decrease with birth year but it is not known if this trend has continued for people born after World War II, members of the Baby Boom (1946-64) or Generation X (1965-81) in the U.S. The purpose of this paper was to determine if the birth cohort effect on incidence of AMD extends to more recent generations and evaluate the impact of potential risk factors on the magnitude of the effect.
Methods:
Data from the Beaver Dam Offspring Study (BOSS) and data from the parental cohort (Beaver Dam Eye Study/Epidemiology of Hearing Loss Study; BDES/EHLS) were included. AMD was graded using digital (BOSS) and film-based images (BDES). The BOSS and BDES/EHLS included questionnaire information about medical history and lifestyle factors and measures of blood pressure, diabetes, cholesterol, etc. A total of 4946 participants born between 1902 and 1984 who did not have AMD at baseline and were re-examined five years later (1988-90 and 1993-95 in the BDES and 2005-2008 and 2010-2013 in the BOSS) were included in these analyses.
Results:
The incidence of AMD declined with birth cohort (generation) and was about 70% lower in each successive generation (age and sex-adjusted OR=0.31; 95%Confidence Interval (CI) = 0.21, 0.44). Adjusting for education, non-HDL cholesterol and statin use,the birth cohort effect remained significant (OR=0.35, 95%CI=0.23, 0.51). Cigarette smoking, diabetes, alcohol consumption, blood pressure, obesity, and exercise also did not modify the effect of generation on incidence of AMD.
Conclusions:
In this study, adults born after World War II had lower risks of AMD than earlier generations. This rapid and continuing decline in the 5-yr incidence of AMD is strong evidence that modifiable factors play important roles in the etiology of AMD. However, including traditional cardiovascular risk factors did not attenuate the generational effect, suggesting that other modifiable factors must contribute to the risk of AMD.
Keywords: 412 age-related macular degeneration •
463 clinical (human) or epidemiologic studies: prevalence/incidence •
464 clinical (human) or epidemiologic studies: risk factor assessment