Abstract
OBJECTIVES: To explore the association between a newly developed cumulative laboratory-based frailty index (FI) and intrinsic (personal) and extrinsic (social, environmental) characteristics. DESIGN: Cross-sectional longitudinal study. SETTING: The third and fourth waves of the community-representative, five-county, 10-year Duke Established Populations for Epidemiologic Studies of the Elderly study, carried out in a health service-rich area. PARTICIPANTS: Cognitively intact survivors of the third wave (N = 1,740), who provided blood samples for standard laboratory work. MEASUREMENTS: Biomarkers (n = 28) were measured to develop a cumulative deficit laboratory test-based FI (Duke FI) derived from standard laboratory tests: SMAC-24 chemistry panel, high-density lipoprotein cholesterol panel, and complete blood count. Information was gathered on scales assessing intrinsic characteristics (personal locus of control, life satisfaction, self-esteem, depressive symptomatology) and extrinsic characteristics (support received from and provided to family and friends, stressful life events, neighborhood disadvantage). RESULTS: The newly developed Duke FI had content, construct, concurrent, and predictive validity. In addition to sex, race, and income, the Duke FI was associated at the intrinsic level with locus of control, self-esteem, life satisfaction, and depressive symptomatology (each P < .01) and at the extrinsic level with provision (P < .01) and with receipt of instrumental help (P < .10), social stressors (P < .03), and neighborhood disadvantage (P < .01) in unadjusted analysis; race fully explained neighborhood disadvantage. CONCLUSION: Intrinsic (personality) characteristics and personally close extrinsic characteristics (contacts with family and friends, personal stressors) are associated with laboratory test-based frailty, as is neighborhood disadvantage, although in this accessible, health service-rich environment, race fully explained association with neighborhood disadvantage, suggesting that interventions to reduce frailty in residents in such an environment should pay particular attention to characteristics that immediately affect the individual.