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Frailty, fitness and late-life mortality in relation to chronological and biological age.

Mitnitski AB, Graham JE, Mogilner AJ, Rockwood K - BMC Geriatr (2002)

Bottom Line: From the frailty index, relative (to CA) fitness and frailty were estimated, as was an individual's biological age.The average value of the frailty index increased with age in a log-linear relationship (r = 0.91; p < 0.001).The frailty index is a sensitive predictor of survival.

View Article: PubMed Central - HTML - PubMed

Affiliation: Ecole Polytechnique, Montreal QB, Canada. arnold@grbb.polymtl.ca

ABSTRACT

Background: People age at remarkably different rates, but how to estimate trajectories of senescence is controversial.

Methods: In a secondary analysis of a representative cohort of Canadians aged 65 and over (n = 2914) we estimated a frailty index based on the proportion of 20 deficits observed in a structured clinical examination. The construct validity of the index was examined through its relationship to chronological age (CA). The criterion validity was examined in its ability to predict mortality, and in relation to other predictions about aging. From the frailty index, relative (to CA) fitness and frailty were estimated, as was an individual's biological age.

Results: The average value of the frailty index increased with age in a log-linear relationship (r = 0.91; p < 0.001). In a Cox regression analysis, biological age was significantly more highly associated with death than chronological age. The average increase in the frailty index (i.e. the average accumulation of deficits) amongst those with no cognitive impairment was 3 per cent per year.

Conclusions: The frailty index is a sensitive predictor of survival. As the index includes items not traditionally related to adverse health outcomes, the finding is compatible with a view of frailty as the failure to integrate the complex responses required to maintain function.

No MeSH data available.


Related in: MedlinePlus

The proportion of survivals for frail (solid rectangles) and fit individuals (total rectangles) decreases with the chronological age. However, frail individuals show lower survival at all age groups than do fit individuals.
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Figure 3: The proportion of survivals for frail (solid rectangles) and fit individuals (total rectangles) decreases with the chronological age. However, frail individuals show lower survival at all age groups than do fit individuals.

Mentions: The impairment index, q ranged from 0 to 1. At any given age, the impairment index is distributed about the mean value for individuals of that age. Figure 2 illustrates this for subjects aged 77 years old who did not demonstrate cognitive impairment. An individual's health status, fi may be defined as a ratio of that person's impairment index to the mean index value, averaged across individuals without cognitive impairment, but of the same chronological age: fi = qi/m; f > 1 if the individual is frail and f < 1 if the individual is fit. The logarithm of the ratio ln(f) may also be considered as an appropriate index of relative frailty/fitness; a positive value of the logarithm indicates frailty, whereas a negative value indicates fitness. (When relative fitness/frailty is to be measured as a dichotomous variable, the mean case is taken as fit; i.e. f < 1.) Figure 3 presents the proportion of fit and frail people who survive, averaged by 5-years intervals. As expected, this decreases with age for both groups, but note that a higher proportion of fit individuals than frail survive in each age group.


Frailty, fitness and late-life mortality in relation to chronological and biological age.

Mitnitski AB, Graham JE, Mogilner AJ, Rockwood K - BMC Geriatr (2002)

The proportion of survivals for frail (solid rectangles) and fit individuals (total rectangles) decreases with the chronological age. However, frail individuals show lower survival at all age groups than do fit individuals.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC88955&req=5

Figure 3: The proportion of survivals for frail (solid rectangles) and fit individuals (total rectangles) decreases with the chronological age. However, frail individuals show lower survival at all age groups than do fit individuals.
Mentions: The impairment index, q ranged from 0 to 1. At any given age, the impairment index is distributed about the mean value for individuals of that age. Figure 2 illustrates this for subjects aged 77 years old who did not demonstrate cognitive impairment. An individual's health status, fi may be defined as a ratio of that person's impairment index to the mean index value, averaged across individuals without cognitive impairment, but of the same chronological age: fi = qi/m; f > 1 if the individual is frail and f < 1 if the individual is fit. The logarithm of the ratio ln(f) may also be considered as an appropriate index of relative frailty/fitness; a positive value of the logarithm indicates frailty, whereas a negative value indicates fitness. (When relative fitness/frailty is to be measured as a dichotomous variable, the mean case is taken as fit; i.e. f < 1.) Figure 3 presents the proportion of fit and frail people who survive, averaged by 5-years intervals. As expected, this decreases with age for both groups, but note that a higher proportion of fit individuals than frail survive in each age group.

Bottom Line: From the frailty index, relative (to CA) fitness and frailty were estimated, as was an individual's biological age.The average value of the frailty index increased with age in a log-linear relationship (r = 0.91; p < 0.001).The frailty index is a sensitive predictor of survival.

View Article: PubMed Central - HTML - PubMed

Affiliation: Ecole Polytechnique, Montreal QB, Canada. arnold@grbb.polymtl.ca

ABSTRACT

Background: People age at remarkably different rates, but how to estimate trajectories of senescence is controversial.

Methods: In a secondary analysis of a representative cohort of Canadians aged 65 and over (n = 2914) we estimated a frailty index based on the proportion of 20 deficits observed in a structured clinical examination. The construct validity of the index was examined through its relationship to chronological age (CA). The criterion validity was examined in its ability to predict mortality, and in relation to other predictions about aging. From the frailty index, relative (to CA) fitness and frailty were estimated, as was an individual's biological age.

Results: The average value of the frailty index increased with age in a log-linear relationship (r = 0.91; p < 0.001). In a Cox regression analysis, biological age was significantly more highly associated with death than chronological age. The average increase in the frailty index (i.e. the average accumulation of deficits) amongst those with no cognitive impairment was 3 per cent per year.

Conclusions: The frailty index is a sensitive predictor of survival. As the index includes items not traditionally related to adverse health outcomes, the finding is compatible with a view of frailty as the failure to integrate the complex responses required to maintain function.

No MeSH data available.


Related in: MedlinePlus