Is Age-Related Macular Degeneration Associated with Stroke Among Elderly Americans?§

Abstract

Objective:To investigate whether age-related macular degeneration (AMD) is associated with the development of ischemic and hemorrhagic stroke among elderly Americans.Design:Population-based cohort study.Participants:The five percent random sample of 2000-2003 Medicare enrollees was obtained. The cohort (n=1,519,086) consisted of enrollees who were aged 65 or older at the first two-year (January 1, 2000 to December 31, 2001).Methods:Baseline demographic variables and chronic conditions (AMD and type, history of myocardial infarction (MI), stroke, hypertension, and diabetes) were defined based on the occurrence of relevant ICD-9 codes in relevant diagnosis fields of the baseline Medicare Data. We excluded 215,900 persons who had a diagnosis of MI or stroke during baseline period to form a cohort of 1,303,186 individuals who were free of major cardio-cerebral vascular disease (CVD) at baseline.Main Outcome Measures:In two years of follow-up (January 1, 2002 to December 31, 2003), a total of 89,501 incident stroke cases were identified, including 80,018 ischemic, 7048 hemorrhagic, and 2,435 stroke cases of both types.Results:Baseline mean age was 75 years (Standard Divination=7.7), with 60% women and 88% whites. The prevalence of AMD was 10.6%, with 19.7% being neovascular AMD and 80.3% being non-neovascular AMD. Baseline age, gender, race, hypertension, and diabetes adjusted 2-year incident odds ratios and 95% confidence internal of stroke associated with AMD were 1.31 (1.26, 1.36) for neovascular AMD, 1.18 (1.15, 1.21) for non-neovascular AMD, and 1.21 (1.18, 1.23) for either neovascular or non-neovascular AMD.Conclusion:The findings are suggestive of an association between AMD, especially neovascular AMD, and incident stroke, independent of demographic factors and co-morbidity. These findings, if confirmed by other studies that control for smoking and other lifestyle covariables not measured in this study, suggest the possibility of shared common antecedents between stroke and AMD.

Age-Related Macular Degeneration and the Risk of Stroke

“…7 Only 1 study divided stroke into subtypes and found that the risks of both cerebral infarction and intracerebral hemorrhage were increased in people with either neovascular or nonneovascular AMD. 8 However, a limitation of the study was that the classification of stroke and AMD were both based on medical reimbursement claims and therefore vulnerable to misclassification. Because the studies conducted so far were heterogeneous with respect to exposure categories and outcome definitions, results are not easily comparable.…”

“…3 Previous studies that investigated the association between AMD and stroke reported inconsistent results. [7][8][9][10][11] Most studies did not distinguish between early and late AMD nor did they subdivide late AMD into dry (atrophic) or wet (neovascular) AMD. Besides, except for a study based on medical reimbursement claims, no previous study presented separate associations for the subtypes cerebral infarction and intracerebral hemorrhage.…”

“…Besides, except for a study based on medical reimbursement claims, no previous study presented separate associations for the subtypes cerebral infarction and intracerebral hemorrhage. 8 The purpose of the present study was to investigate in a large population-based cohort of elderly people if AMD was associated with risk of stroke and its subtypes cerebral infarction and intracerebral hemorrhage. In addition, we analyzed if any of these associations also held for the various AMD stages.…”

Age-Related Macular Degeneration

“…Similar findings have been reported from a survey of 1.4 million Medicare enrollees, which found 20% to 30% higher 2-year risk of stroke among patients with neovascular AMD as compared with control subjects. 6 In the current issue of Stroke, Hu and colleagues further report on this association. 8 Using a national linkage database in Taiwan, the authors showed that patients with a neovascular AMD diagnosis had a 2-fold higher incidence of stroke than those without AMD (18.2% versus 9.9%), and this association persisted while controlling for concomitant vascular risk factors.…”

Neovascular Age-Related Macular Degeneration and the Risk of Stroke

“…12 Two reports based on US Medicare data showed inconsistent results. Liao et al reported that neovascular AMD was associated with higher adjusted 2-year incidence of stroke (8.15% versus 6.35%; OR 1.31, 95% CIϭ1.26 to 1.36), 13 but Alexander et al reported that Medicare beneficiaries with neovascular AMD had an annual rate of inpatient ischemic stroke similar to that of matched control subjects (3.5% versus 3.6%). 11 Based on a representative database and sufficient neovascular AMD case numbers (Nϭ209), our results are compatible with most previous reports, supporting an association between neovascular AMD and a higher incidence of stroke.…”