A comparison of two approaches to measuring frailty in elderly people.pdf

A comparison of two approaches to measuring frailty in elderly people Kenneth Rockwood,1,2 Melissa Andrew,1,2 Arnold Mitnitski2 The Journal of Gerontology – Medical Sciences As accepted, December, 2006 1Division of Geriatric Medicine, 2Department of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada Address for correspondence: Kenneth Rockwood, Centre for Health Care of the Elderly, 1421-5955 Veterans’ Memorial Lane, Halifax, Nova Scotia, Canada, B3H 2E1. Telephone: 902-473-8687. Fax: 902-473-1050. Kenneth.Rockwood@Dal.ca Text word count: 2584 Total word count: 4661 Running Head: Comparing two approaches to frailty Abstract Background. Many definitions of frailty exist, but few have been directly compared. We compared the relationship between a definition of frailty based on a specific phenotype with one based on an index of deficit accumulation. Methods. The data come from all 2305 people aged 70 years and older who comprised the clinical examination cohort of the second wave of the Canadian Study of Health and Aging. We tested convergent validity by correlating the measures with each other and with other health status measures, and analyzed cumulative index distributions in relation to phenotype. To test criterion validity, we evaluated survival (institutionalization and all- cause mortality) by frailty index (FI) score, stratified by the phenotypic definitions as “robust”, “pre-frail” and “frail”. Results. The measures correlated moderately well with each other (R=0.65) and with measures of function (phenotypic definition R=0.66; FI, R=0.73) but less well with cognition (phenotypic definition, R=-0.35; FI R=-0.58;). The median FI scores increased from 0.12 for the robust to 0.30 for the pre-frail and 0.44 for the frail. Survival was also less with increasing frailty, and institutionalization was more common, but within each phenotypic class, there were marked differences in outcomes based on t