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J Gerontol A Biol Sci Med Sci. 2005 Aug;60(8):1013-6.

Estimates of active and disabled life expectancy based on different assessment intervals.

Author information

1
Department of Internal medicine, Yale University School of Medicine, New Haven, CT 06504, USA. gill@ynhh.org

Abstract

BACKGROUND:

Although disability in activities of daily living (ADLs) is a highly dynamic process, analytic strategies for estimating active and disabled life expectancy have assumed stability in ADL function between periodic surveys spanning 12--24 months or have used interval estimation or instantaneous rates based on long assessment intervals. We performed a prospective cohort study to compare estimates of active and disabled life expectancy based on traditional assessment intervals of 1--2 years with those based on more frequent assessments at 1-month intervals.

METHODS:

Participants included 754 initially nondisabled community-dwelling persons, aged 70 years or older, who were interviewed monthly for 4 years to ascertain ADL disability. Estimates of active and disabled life expectancy were calculated using an increment-decrement life table for assessment intervals of 1 month, 1 year, and 2 years.

RESULTS:

For each of five age groups, the monthly assessment strategy yielded the highest values for active life expectancy and the lowest values for disabled life expectancy. The 95% confidence intervals for these values, however, overlapped the corresponding point estimates for the annual and biennial strategies.

CONCLUSIONS:

Accurate estimates of active and disabled life expectancy may be obtained from epidemiologic studies that assess ADL function no more frequently than every other year.

PMID:
16127105
DOI:
10.1093/gerona/60.8.1013
[Indexed for MEDLINE]

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