Changes with age in the distribution of a frailty index.
Models of human mortality include a factor that summarises intrinsic differences in individual rates of ageing, commonly called frailty. Frailty also describes a clinical syndrome of apparent vulnerability. In a representative, cross-sectional, Canadian survey (n = 66,589) we calculated a frailty index as the mean accumulation of deficits and previously showed it to increase exponentially with age. Here, its density function exhibited a monotonic change in shape, being least skewed at the oldest ages. Although the shape gradually changed, the frailty index was well fitted by a gamma distribution. Of note, the variation coefficient, initially high, decreased from middle age on. Being able to quantify frailty means that health risks can be summarised at both the individual and group levels.
Rockwood
Kenneth
K
Division of Geriatric Medicine, Department of Medicine, Dalhousie University, 1421-5955 Veterans Memorial Lane, Halifax, Nova Scotia B3H 1C6, Canada. Kenneth.Rockwood@dal.ca
Mogilner
Alexander
A
Mitnitski
Arnold
A
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D002170:Canada; D005260:Female; D016330:Frail Elderly / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018401:Sample Size