Melbourne School of Population and Global Health - Research Publications
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ItemNovel measures of cardiovascular health and its association with prevalence and progression of age-related macular degeneration: the CHARM study(BMC, 2008)BACKGROUND: To determine if novel measures of cardiovascular health are associated with prevalence or progression of age-related macular degeneration (AMD). METHODS: Measures of the cardiovascular system: included intima media thickness (IMT), pulse wave velocity (PWV), systemic arterial compliance (SAC), carotid augmentation index (AI). For the prevalence study, hospital-based AMD cases and population-based age- and gender-matched controls with no signs of AMD in either eye were enrolled. For the progression component, participants with early AMD were recruited from two previous studies; cases were defined as progression in one or both eyes and controls were defined as no progression in either eye. RESULTS: 160 cases and 160 controls were included in the prevalence component. The upper two quartiles of SAC, implying good cardiovascular health, were significantly associated with increased risk of AMD (OR = 2.54, 95% CL = 1.29, 4.99). High PWV was associated with increased prevalent AMD. Progression was observed in 82 (32.3%) of the 254 subjects recruited for the progression component. Higher AI (worse cardiovascular function) was protective for AMD progression (OR = 0.30, 95%CL = 0.13, 0.69). Higher aortic PWV was associated with increased risk of AMD progression; the highest risk was seen with the second lowest velocity (OR = 6.22, 95% CL = 2.35, 16.46). CONCLUSION: The results were unexpected in that better cardiovascular health was associated with increased risk of prevalent AMD and progression. Inconsistent findings between the prevalence and progression components could be due to truly different disease etiologies or to spurious findings, as can occur with inherent biases in case control studies of prevalence. Further investigation of these non-invasive methods of characterizing the cardiovascular system should be undertaken as they may help to further elucidate the role of the cardiovascular system in the etiology of prevalent AMD and progression.
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ItemCan genetic associations change with age? CFH and age-related macular degeneration(OXFORD UNIV PRESS, 2012-12-01)Genetic variation in the gene encoding complement factor H (CFH) on chromosome 1q31 has repeatedly been associated with an increased risk of age-related macular degeneration (AMD); however, previous studies have had inadequate numbers of participants across a sufficiently wide age range to determine whether the association varies by age. We conducted a genetic case-control study using data from 2294 cases and 2294 controls selected from the Melbourne Collaborative Cohort Study, matched on age, sex and region of origin. Four consistently replicated CFH single-nucleotide polymorphisms (SNPs) were genotyped: rs1061170 (Y402H), rs2274700, rs393955 and rs800292; their relationship with AMD prevalence was determined across the age range 48-86. A difference in genotype frequencies was seen across age groups, where the low-risk homozygote prevalence rose with each increasing age group. Associations with early AMD were strongly modified by age for three of the four SNPs (interaction P-value: 0.01-0.00003). An inverse association between the high-risk homozygote for each SNP and early AMD was observed in the younger age groups [odds ratios (OR) range 0.37-0.48 for age <55], reversing to a positive association with increasing age (OR 1.87-2.8 for age >75). The direction of associations for this gene change was from inverse to risk with increasing age. These findings have important implications for predictive models for AMD and potentially other age-related diseases which extrapolate risks from older cohorts, as they assume homogeneity of association by age, which might not exist.
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ItemAge Related Macular Degeneration and Total Hip Replacement Due to Osteoarthritis or Fracture: Melbourne Collaborative Cohort Study(PUBLIC LIBRARY SCIENCE, 2015-09-10)Osteoarthritis is the leading cause of total hip replacement, accounting for more than 80% of all total hip replacements. Emerging evidence suggests that osteoarthritis has a chronic inflammatory component to its pathogenesis similar to age-related macular degeneration. We evaluated the association between age-related macular degeneration and total hip replacement as proxy for severe osteoarthritis or fractured neck of femur in the Melbourne Collaborative Cohort Study. 20,744 participants had complete data on both age-related macular degeneration assessed from colour fundus photographs taken during 2003-2007 and total hip replacement. Total hip replacements due to hip osteoarthritis and fractured neck of femur during 2001-2011 were identified by linking the cohort records to the Australian Orthopedic Association National Joint Replacement Registry. Logistic regression was used to examine the association between age-related macular degeneration and risk of total hip replacement due to osteoarthritis and fracture separately, adjusted for confounders. There were 791 cases of total hip replacement for osteoarthritis and 102 cases of total hip replacement due to fractured neck of femur. After adjustment for age, sex, body mass index, smoking, and grouped country of birth, intermediate age-related macular degeneration was directly associated with total hip replacement for osteoarthritis (odds ratio 1.22, 95% CI 1.00-1.49). Late age-related macular degeneration was directly associated with total hip replacement due to fractured neck of femur (odds ratio 5.21, 95% CI2.25-12.02). The association between intermediate age-related macular degeneration and an increased 10-year incidence of total hip replacement due to osteoarthritis suggests the possibility of similar inflammatory processes underlying both chronic diseases. The association of late age-related macular degeneration with an increased 10-year incidence of total hip replacement due to fractured neck of femur may be due to an increased prevalence of fractures in those with poor central vision associated with the late complications of age-related macular degeneration.
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ItemNo Preview Available20/20-Alcohol and Age-related Macular Degeneration: The Melbourne Collaborative Cohort Study(OXFORD UNIV PRESS INC, 2012-08-15)Little evidence exists regarding associations between age-related macular degeneration (AMD) and moderate alcohol consumption, patterns of consumption, or different types of alcoholic beverage. The authors examined associations between AMD prevalence and alcohol intake using 20,963 participants from the Melbourne Collaborative Cohort Study aged 40-69 years at baseline (1990-1994). Participants' alcohol consumption was determined from a structured interview at baseline. At follow-up from 2003 to 2007, digital macula photographs of both eyes were taken and evaluated for early and late AMD signs. Drinking more than 20 g of alcohol per day was associated with an approximate 20% increase in the odds of early AMD (odds ratio = 1.21, 95% confidence interval: 1.06, 1.38; P = 0.004) when compared with those who reported no alcohol intake at baseline, having adjusted for sex, age, smoking, country of birth, education, physical activity, and energy from food. This positive association was apparent for wine, beer, and spirits. The estimates were similar for both sexes. The odds ratio for those drinking more than 20 g of alcohol per day for late AMD was 1.44 (95% confidence interval: 0.85, 2.45; P = 0.17). These results show a modest association between alcohol consumption and increased AMD risk.