Joint Dependence of Severe Cognitive Impairment and ADL Disability in the U.S. Elderly Population: Estimates from the 2004 National Long Term Care Survey

Eric Stallard, Duke University

Purpose: To estimate the joint distribution of severe cognitive impairment (SCI) and ADL disability among aged Medicare enrollees using HIPAA disability triggers. Methods: ADL disability was defined as active personal assistance in 2+ ADLs. SCI was defined as 3+ SPMSQ errors, caregiver report of Alzheimer’s disease/dementia, or similar problems, with concurrent substantial supervision. Results: Overall prevalence rates were 8.2% for ADL disability, 6.7% for SCI, and 10.1% for ADL+SCI combined. Sex differences in ADL+SCI were large: 7.5% (males) v. 12.0% (females). Conditional probabilities of SCI for community residents increased from 22% at 1 ADL to 65% at 6 ADLs; for institutional residents, from 50% at 1 ADL to 90% at 6 ADLs; and for both residence types, from 26% at 1 ADL to 78% at 6 ADLs. Conclusions: SCI and ADLs exhibited complex dependencies by residence type and sex. Demographic analyses that ignore these dependencies may be severely biased.