Oct. 15, 2009 Visual problems that cannot be corrected are associated with increased risk of death among individuals between the ages of 49 and 74, and all visual impairments may be associated with the risk of death in older adults, according to a report in the October issue of Archives of Ophthalmology, one of the JAMA/Archives journals.
Visual impairment has been associated with a higher risk of death as well as factors that may lead to increased death such as unintentional injury, depression, lower body mass index (BMI), reduced walking speeds, increased risk of falls, self-reported difficulty in physical activity, cardiovascular disease, dementia and cancer, according to background information in the article. "Correction for these 'confounders' has been found to attenuate the association between visual impairment and mortality, but the mechanisms behind the association between visual impairment and mortality remain to be determined."
Michael J. Karpa, M.B.B.S., B.Sc., of Westmead Millennium Institute, Sydney, Australia, and colleagues used data from the Blue Mountains Eye Study, which examined visual impairment in 3,654 participants age 49 and older between 1992 and 1994 and after five and ten years, to evaluate the relationship between visual impairment and death risk among older individuals.
At baseline, participants with noncorrectable visual impairment were more likely to be female, age 75 and older and underweight. Those with correctable visual impairment were more likely to be age 75 and older, but had no difference in proportions of women or BMI.
Thirteen years after baseline, 1,273 participants had died. A higher risk of dying was associated with noncorrectable visual impairment, with a stronger association for participants younger than age 75. The analyses "revealed greater effects of noncorrectable visual impairment on mortality risk, with both direct and indirect effects," the authors write. "Of mortality risk markers examined, only disability in walking demonstrated a significant indirect pathway for the link between visual impairment and mortality."
"In conclusion, this study reaffirms that visual impairment is associated with an increased risk of all-cause mortality," the authors write. "Disability in walking may represent an important indirect pathway to mortality for persons with visual impairment, and adjusting for this factor in statistical analysis may overadjust for the indirect effect of visual impairment on mortality risk. The impact of visual impairment on mortality may in fact be greater than that reported from previous studies that have used traditional statistical models."
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- Michael J. Karpa; Paul Mitchell; Ken Beath; Elena Rochtchina; Robert G. Cumming; Jie Jin Wang. Direct and Indirect Effects of Visual Impairment on Mortality Risk in Older Persons: The Blue Mountains Eye Study. Arch Ophthalmol, 2009; 127 (10): 1347-1353 [link]
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