Original articles
How to Select a Frail Elderly Population? A Comparison of Three Working Definitions

https://doi.org/10.1016/S0895-4356(99)00077-3Get rights and content

Abstract

Aim of this study was to compare three different working definitions for selecting a frail elderly population. Frailty was defined as inactivity combined with (1) low energy intake (n = 29), (2) weight loss (n = 26), or (3) low body mass index (n = 26). In the Zutphen Elderly Study (n = 450; age 69–89 years) differences in health, functioning, and diet in 1990 and functional decline and mortality in the following 3 years between “frail” and “nonfrail” participants, according to the working definitions, were studied using logistic regression analysis. Differences according to the inactivity/weight loss criterium were more pronounced than according to the other two criteria. Inactivity/weight loss was associated with lower subjective health and performance and more diseases and disabilities in 1990. Three-year relative risks of mortality (odds ratio [OR]: 4.1, 1.8–9.4) and functional decline (OR: 5.2, 1.04–25.8 for disabilities, OR: 3.7, 0.8–16.2 for performance) were higher as well. Inactivity in combination with weight loss seems a practicable working definition for selecting a frail elderly population.

Introduction

Physical frailty represents a large threat to older people's functioning and quality of life. Many studies have focused on “frail elderly.” Still, criteria used for selection of these frail elderly are unstandardized. Often the term frail elderly is used to denote those living in institutions or with impaired functional status. This makes the difference between frailty and functional dependence unclear. Buchner and Wagner [1] defined frailty as a state of reduced physiologic reserve associated with increased susceptibility to disability. Rockwood et al. [2] defined as frail those who depend on others for the activities of daily living or who are at high risk of becoming dependent. Except in institutions, frail elderly can also be found among the noninstitutionalized. Preventive strategies and targeted services for frail elderly people require identification of this risk group, preferably before disability and institutionalization have occurred.

Two major determinants of frailty are physical inactivity and malnutrition. Both increase the risk of muscle weakness, which is associated with disability 1, 3, 4. The positive effects of physical activity on muscle strength, bone mass, and functional independence 5, 6, 7 have repeatedly been demonstrated. Inadequate dietary intake and nutritional deficiencies are also important causes of the age-related decline in muscle mass and impaired physiologic functioning 4, 8.

Inactivity and malnutrition interact in their impact on frailty. Inactivity may decrease appetite and, consequently, dietary intake, resulting in malnutrition, muscle dysfunction, and further inactivity: a downward process evolves. Preventing disability and further deterioration requires identification of elderly at the beginning of this downward process. Possible early makers of frailty may be physical inactivity and low energy intake. Low body mass index (BMI) and weight loss as indicators of a decline in muscle mass may be other early markers of frailty. Both low body weight and weight loss in old age have been associated with poor health and disability [9]. The aim of the present study was to examine three working definitions of frailty using data from the 1990 survey of an ongoing follow-up study. Frailty was defined as physical inactivity combined with either low energy intake, 5-year weight loss, or low BMI. Associations between frailty—according to these three working definitions—and health, functioning, diet (cross-sectional), and decline in functioning and mortality in the following 3 years were studied.

Section snippets

Study Population

The Zutphen Study is a longitudinal study on chronic diseases and risk factors and constitutes the Dutch contribution of the Seven Countries Study [10]. It originally started in 1960 with a cohort of 878 men, aged 40–59 years, living in the town of Zutphen in the Netherlands. In 1985, 555 men were still alive and were invited for a new examination along with an additional random sample of 711 men of the same age (65–84 years old). In 1985, 939 of these men (response rate 74%) were investigated,

Results

Mean values of the selection criteria are shown in Table 1. The inactivity/low energy intake criterium resulted in 29 frail (6%) and 421 nonfrail men. The inactivity/weight loss and inactivity/BMI criteria both resulted in 26 frail (6%) and 424 nonfrail men. Seven men were defined as frail according to both inactivity/weight loss and inactivity/low energy; 9, according to both inactivity/weight loss and inactivity/low BMI; and 6, according to both inactivity/low energy and inactivity/low BMI.

Discussion

The results of our study indicate that inactivity in combination with weight loss seems to be a suitable working definition for selecting a frail elderly population among community-dwelling elderly men. Participants who were inactive and had lost more than 4 kg in 5 years had an adverse health profile (lower self-rated and physician-rated health, more diseases) and functional capacity (more disabilities, lower grip strength, walking speed, standing balance, and chair stand performance) compared

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