To search for factors that contribute to the development of neovascularage-related macular degeneration (AMD).
In a matched-pair case-control study, we studied sib pairs in whichthe index sibling had neovascular AMD in at least 1 eye and the unaffectedsibling had normal maculae (or at most only a few small drusen) and was pastthe age at which the index case was diagnosed. Factors studied included sex,iris color, education, alcohol consumption, body mass index, vitamin use,smoking history, hypercholesterolemia, aspirin use, hypertension, other cardiovasculardisease, any autoimmune disease, and non–insulin-dependent diabetesmellitus. Conditional logistic regression was performed to identify predictorsof neovascular AMD.
On the basis of 73 sib pairs, multivariate regression analysis revealeda statistically significant 2% increase in risk of neovascular AMD with eachpack-year of smoking (odds ratio, 1.02; 95% confidence interval, 1.01-1.04; P = .007). Suggestive but nonsignificant associations werealso observed for mean lifetime alcohol consumption, adult lifetime body massindex, and hypertension in multivariate regression analyses.
Using extremely discordant sib pairs to study risk factors for AMD,a novel approach in epidemiological design, we found evidence that smokingis a risk factor for neovascular AMD.