Abstract
Purpose: :
Data from population-based epidemiological studies are necessary, in order to better estimate the associations of Complement Factor H (CFH) with age-related maculopathy (ARM). In particular, few data are available on non-neovascular ARM and on the respective roles of CFH and smoking.
Methods: :
The Alienor Study is a population-based study on nutrition and age-related eye diseases. 963 subjects were recruited from September 2006 to May 2008. CFH polymorphism was determined in 878 subjects (91.2 %), from DNA collected in 1999-2001. 796 of 878 (90.7 %) had gradable photographs and were classified in 5 exclusive stages (worse eye): neovascular ARM (stage 4, n= 22); geographic atrophy (stage 3, n=22); large soft indistinct drusen and/or reticular drusen and/or large distinct drusen with pigment abnormalities (stage 2, n=87); large soft distinct drusen alone or pigment abnormalities alone (stage 1, n=144); stage 0 (n=521). Associations were estimated using polytomous logistic regression, after adjustment for age and gender, stage 0 being the reference in all analyses.
Results: :
CFH polymorphism was strongly associated with neovascular ARM (OR= 9.9, 95 % confidence interval (CI) 2.3 - 41.8, p= 0.002 for TC subjects and OR= 5.2, 95 % CI: 1.4 - 18.4, p= 0.01 for CC subjects, vs TT subjects) and stage 2 ARM (OR=2.2, 95 % : 1.1 - 4.4, p=0.01 and OR=1.6, 95 % CI: 1.0 - 2.7, p= 0.06, respectively). It was not significantly associated with geographic atrophy (OR= 0.8, 95 %CI : 0.2 - 3.8, p= 0.79 and OR= 0.6, 95 % CI : 0.2 - 1.6 , p=0.30, respectively) and stage 1 ARM (OR=1.5, 95 % CI : 0.8 - 2.6, p=0.20 and OR= 1.0, 95 % CI: 0.7 - 1.5, p=0.90). Subjects having smoked 20 pack-years or more had significantly increased risk of neovascular ARM (OR=3.4, 95 % CI: 1.1 - 10.8, p=0.04), but not of geographic atrophy (OR= 1.0, 95 % CI : 0.3 - 3.3, p=0.96). They were also at higher risk of stage 2 ARM (OR= 1.9, 95 % CI: 1.0 - 3.4, p=0.04) and tended to be at higher risk of stage 1 ARM (OR= 1.5, 95 % CI : 0.9 - 2.5, p=0.11). Associations of ARM stages with smoking were not affected by further adjustment on CFH polymorphism. No statistical interactions of CFH with smoking were detected.
Conclusions: :
This population-based study confirms the contribution of both CFH and smoking to the aetiology of ARM. CFH was associated with neovascular and early (stage 2) ARM, but not with geographic atrophy.
Keywords: age-related macular degeneration • clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • clinical (human) or epidemiologic studies: risk factor assessment