Assessing Risk for Adverse Outcomes in Older Adults: The Need to Include Both Physical Frailty and Cognition

Abstract

BACKGROUNDPhysical frailty is a powerful tool for identifying nondisabled individuals at high risk of adverse outcomes. The extent to which cognitive impairment in those without dementia adds value to physical frailty in detecting high-risk individuals remains unclear. OBJECTIVESTo estimate the effects of combining physical frailty and cognitive impairment without dementia (CIND) on the risk of basic activities of daily living (ADL) dependence and death over 8 years. DESIGNProspective cohort study. SETTINGThe Health and Retirement Study (HRS). PARTICIPANTSA total of 7338 community-dwelling people, 65 years or older, without dementia and ADL dependence at baseline (2006-2008). Follow-up assessments occurred every 2 years until 2014. MEASUREMENTSThe five components of the Cardiovascular Health Study defined physical frailty. A well-validated HRS method, including verbal recall, series of subtractions, and backward count task, assessed cognition. Primary outcomes were time to ADL dependence and death. Hazard models, considering death as a competing risk, associated physical frailty and CIND with outcomes after adjusting for sociodemographics, comorbidities, depression, and smoking status. RESULTSThe prevalence of physical frailty was 15%; CIND, 19%; and both deficits, 5%. In unadjusted and adjusted analyses, combining these factors identified older adults at an escalating risk for ADL dependence (no deficit = 14% [reference group]; only CIND = 26%, sub-hazard ratio [sHR] = 1.5, 95% confidence interval [CI] = 1.3-1.8; only frail = 33%, sHR = 1.7, 95% CI = 1.4-2.0; both deficits = 46%, sHR = 2.0, 95%CI = 1.6-2.6) and death (no deficit = 21%; only CIND = 41%, HR = 1.6, 95% CI = 1.4-1.9; only frail = 56%, HR = 2.2, 95% CI = 1.7-2.7; both deficits = 66%, HR = 2.6, 95% CI = 2.0-3.3) over 8-year follow-up. Adding the cognitive measure to models that already included physical frailty alone increased accuracy in identifying those at higher risk of ADL dependence (Harrell's concordance [C], 0.74 vs 0.71; P < .001) and death (Harrell's C, 0.70 vs 0.67; P < .001). CONCLUSIONPhysical frailty and CIND are independent predictors of incident disability and death. Because together physical frailty and CIND identify vulnerable older adults better, optimal risk assessment should supplement measures of physical frailty with measures of cognitive function. J Am Geriatr Soc 67:477-483, 2019.