Accumulation of Deficits as a Proxy Measure of Aging

Abstract

This paper develops a method for appraising health status in elderly people. A frailty index was defined as the proportion of accumulated deficits (symptoms, signs, functional impairments, and laboratory abnormalities). It serves as an individual state variable, reflecting severity of illness and proximity to death. In a representative database of elderly Canadians we found that deficits accumulated at 3% per year, and show a gamma distribution, typical for systems with redundant components that can be used in case of failure of a given subsystem. Of note, the slope of the index is insensitive to the individual nature of the deficits, and serves as an important prognostic factor for life expectancy. The formula for estimating an individual's life span given the frailty index value is presented. For different patterns of cognitive impairments the average within-group index value increases with the severity of the cognitive impairment, and the relative variability of the index is significantly reduced. Finally, the statistical distribution of the frailty index sharply differs between well groups (gamma distribution) and morbid groups (normal distribution). This pattern reflects an increase in uncompensated deficits in impaired organisms, which would lead to illness of various etiologies, and ultimately to increased mortality. The accumulation of deficits is as an example of a macroscopic variable, i.e., one that reflects general properties of aging at the level of the whole organism rather than any given functional deficiency. In consequence, we propose that it may be used as a proxy measure of aging.

Prevalence of and factors associated with frailty and disability in older adults from China, Ghana, India, Mexico, Russia and South Africa

“…Frailty was measured using the deficit accumulation approach [8]. A frailty index was constructed as the proportion of deficits present out of 40 variables available in the SAGE database (as shown in Appendix 1).…”

“…The literature currently points to several definitions of frailty, with no common consensus [6]. The two most common operational definitions of frailty are the physical frailty phenotype [5] and the frailty index which is based on the deficit accumulation approach [8]. For disability, an assessment of functioning in activities of daily living (ADLs) is one method commonly used to assess disability in older persons [9,10].…”

The Role of Emergency Medical Services in Geriatrics: Bridging the Gap between Primary and Acute Care

“…10 Alternatively, it has been described as an accumulation of deficits or health problems. 11 Frailty is an independent predictor of poor outcomes in the ED population, 7,12 and is also predictive of morbidity, mortality, and adverse events in critically ill patients 13 . It can be challenging for ED staff to have the time and resources required to accurately identify frailty.…”

A Poisson-like model of sub-clinical signs from the examination of healthy aging subjects

“…In the first, components of large data sets, such as the Canadian Study of Health and Aging (CSHA) and the Longitudinal Study of Aging (LSOA) in the US, are used to define characteristics of an aging population over time. It is possible in this approach to define markers of aging through the counting of deficits (22). The related construction of a frailty index (often the ratio of the number of deficits observed to the total possible) can be a stand-in for "biological age" of a subject (23).…”