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RESEARCH STUDY

RESEARCH

Direct and Indirect Effects of Visual Impairment on Mortality Risk in Older Persons - the Blue Mountains Eye Study

AUTHOR:

Michael J. Karpa, MBBS, BSc, Paul Mitchell, MD, PhD; Ken Beath, BE, MAppStat; Elena Rochtchina, MAppStat; Robert G. Cumming, MBBS, PhD; Jie Jin Wang, MMed, PhD

SPONSOR/INSTITUTION:

National Health and Medical Research Council (Australia)

YEAR PUBLISHED:

2009

PUBLICATION:

JAMA Ophthalmology

KEY HIGHLIGHTS:

  • The objective of this study was to investigate pathways from visual impairment to increased all-cause mortality in older persons.

  • The Blue Mountains Eye Study examined 3654 persons 49 years and older (82.4% response) during 1992-1994 and after 5 and 10 years.

  • Visual impairment was defined as presenting, correctable, and noncorrectable, using better-eye visual acuity.

  • Associations between visual impairment and mortality risk were estimated using Cox regression and structural equation modeling.

  • Visual impairment has consistently been associated with a higher risk of dying.

  • Visual impairment is also reportedly associated with many factors also linked to increased mortality, imcluding unintentional injury, reduced walking speed, depression, increased risk of falls, and difficulty in physical activity.

  • Researchers concluded that visual impairment predicted mortality by both direct and indirect pathways, particularly for persons younger than 75 years with noncorrectable visual impairment.

  • Disability in walking, which can substantially influence general health, represented a major indirect pathway.

SUMMARY

The Blue Mountains Eye Study examined 3654 persons 49 years and older (82.4% response) during 1992-1994 and after 5 and 10 years. The objective of this study was to investigate pathways from visual impairment to increased all-cause mortality in older persons.

Visual impairment was defined as presenting, correctable, and noncorrectable, using better-eye visual acuity. Associations between visual impairment and mortality risk were estimated using Cox regression and structural equation modeling.


Visual impairment has consistently been associated with a higher risk of dying. Visual impairment is also reportedly associated with many factors also linked to increased mortality. These include unintentional injury, reduced walking speed, depression, lower body mass index (BMI), increased risk of falls, difficulty in physical activity, systemic inflammation, cardiovascular disease, dementia, and cancer. 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.


Researchers utilized structural equation modeling (SEM), a statistical method that permits modeling of complex relationships that are difficult to estimate using traditional regression techniques, and concluded that visual impairment predicted mortality by both direct and indirect pathways, particularly for persons younger than 75 years with noncorrectable visual impairment. Disability in walking, which can substantially influence general health, represented a major indirect pathway.


Arch Ophthalmol. 2009;127(10):1347-1353. doi:10.1001/archophthalmol.2009.240.