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J.S. Tan, A. Shanker, E. Rochtchina, W. Smith, P. Mitchell, J.J. Wang, Blue Mountains Eye Study; White Blood Cell Count and the 10–Year Incidence of Age–Related Maculopathy: The Blue Mountains Eye Study . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2136.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the relationship between baseline white blood cell (WBC) count level and the risk of 10–year incident age related maculopathy (ARM) in an older population.
The Blue Mountains Eye Study is a population–based cohort study of 3654 persons aged 49+ years at baseline, of whom 2335 participated in the 5–year and 1952 in the 10–year follow up examinations. At baseline fasting blood sample was taken from 3222 (88%) participants and WBC count was determined using a Coulter counter method. Incident ARM was defined either late or early ARM, or early ARM lesions, developed in participants without corresponding lesions at baseline. Kaplan–Meier (product limit) estimates and discrete logistic regression models were used to incorporate incident cases detected at either the 5–year or 10–year examinations, while adjusting for baseline age, sex and smoking status.
10–year incidence rates of late ARM were 2.8%, 3.2% and 4.5% for subjects in the lowest, middle and highest tertile of WBC, respectively, with adjusted relative risk (RR) 1.2, CI 0.6–2.4 for the middle and RR 1.8, CI 0.96–3.4 for the highest tertile compared to the lowest (p for trend=0.06). The association between the highest WBC tertile and the incidence of late ARM was mainly driven by the association between WBC and incident geographic atrophy (RR 2.4, CI 0.98–5.8) but not incident neovascular ARM (RR 1.2, CI 0.5–2.8). 10–year incidence rates for early ARM were 10.9%, 13.6% and 18.3% for subjects in the three WBC tertiles, respectively, adjusted relative risk (RR) 1.3, CI 0.9–1.9 for the middle and RR 1.9, CI 1.3–2.6 for the highest tertile compared to the lowest (p for trend=0.0003). A similar trend of association was evident for incident retinal pigmentary abnormalities (RR 1.2, CI 0.9–1.5 and RR 1.4, CI 1.1–1.9 for the two higher tertiles, p for trend=0.008) and for incident soft indistinct or reticular drusen (RR 1.2, CI 0.8–1.7 and RR 1.6, CI 1.2–2.3 for the two higher tertiles, p for trend=0.006). These associations appeared to be stronger in men (RR 5.5, CI 1.2–25.2 for late and RR 3.0, CI 1.7–5.6 for early ARM) than in women (RR 1.2, CI 0.6–2.6 for late and RR 1.5, CI 0.97–2.2 for early ARM), compared the highest to lowest tertile.
A high WBC level was independently associated with an increased long–term risk of developing early and late ARM in older Australians, particularly in men.
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