Elsevier

Archives of Gerontology and Geriatrics

Volume 54, Issue 1, January–February 2012, Pages 16-20
Archives of Gerontology and Geriatrics

A comparison of frailty indexes for prediction of adverse health outcomes in an elderly cohort

https://doi.org/10.1016/j.archger.2011.01.007Get rights and content

Abstract

This study aimed to compare the predictive accuracy for several frailty-related adverse health outcomes of a cumulative index derived from the Italian population-based elderly cohort of the Conselice Study of Brain Aging (CSBA), which takes into account multiple different domains (demographic, clinical, functional, and nutritional parameters), with that of an index derived from the Study of Osteoporotic Fractures (SOF), modified for application to the CSBA database and henceforth called mSOF, which is exclusively focused on muscular fitness. Data are for 1007 CSBA participants aged ≥65 years. Investigated adverse outcomes included 4- and 7-year risk of death and 4-year risk of fractures, falls, disability, hospitalization, and nursing home placement. Accuracy for prediction of these outcomes was investigated using area under the curve (AUC) statistics. CSBA index performed better than mSOF index for prediction of mortality (p < 0.001), hospitalization (p = 0.002), and nursing home placement (p = 0.049). For all outcomes excluding falls, frailty defined by CSBA index had a slightly lower specificity but a much higher sensitivity than frailty defined by mSOF Index. In conclusion, in this elderly cohort, the multidimensional CSBA index is a better predictor of frailty-related adverse health outcomes than the unidimensional mSOF index.

Introduction

Frailty is a condition that makes elderly persons highly vulnerable to adverse health outcomes (Hogan et al., 2003). Identification of frail persons is of interest for both researchers and clinicians, but a uniformly accepted operational definition for frailty is still lacking (Martin and Brighton, 2008).

According to the physical phenotype of frailty that Fried et al. (2001) developed from the Cardiovascular Health Study (CHS) cohort, frailty is defined as a cluster of five measurements related to muscular mass and strength, taken as indicators of physical fitness. As a construct that neatly distinguishes frailty from disability and comorbidity, the physical phenotype is designed to capture pre-clinical states of pure physiologic vulnerability and has provided very valuable insights about frailty's biology and physiology (Walston et al., 2006). A simplified, 3-item version of the CHS index has been developed from the SOF cohorts and proposed for clinical use (Ensrud et al., 2008, Ensrud et al., 2009).

Geriatricians, however, are most often faced with full-blown frailty, when physical vulnerability has already progressed toward functional impairment and its clinical repercussions are heavily affected by, and often inseparably interlaced with, comorbidity, sensory loss, and psychosocial status (Walston et al., 2006, Whitson et al., 2007, Hubbard et al., 2009). This stage of frailty may be best described as an accumulation of multifactorial deficits (Hogan et al., 2003, Walston et al., 2006, Martin and Brighton, 2008). Several cumulative indexes exist but, due to the high number of included items, their lack of standard norm, or the need of specific equipment for their measurement, most of them are challenging for clinical use (Bergman et al., 2007).

Using data from the CSBA, an Italian population-based cohort of elderly people, we previously proposed a cumulative frailty index including only nine standardized measurements (Ravaglia et al., 2008). In this paper, data from the same cohort were used to compare the ability of the CSBA and mSOF index for prediction of several adverse outcomes known to be related to frailty.

Section snippets

Subjects and setting

The CSBA is a population-based prospective survey of Italian elderly people aimed to provide epidemiological data about age-related cognitive disorders, as detailed elsewhere (Ravaglia et al., 2005). Briefly, in 1999/2000, 1016 (75%) of the 1353 individuals aged 65 years and older residing in the Conselice municipality (Emilia Romagna Region, Northern Italy) were enrolled for baseline examination. In 2003/2004, survivors underwent a follow-up examination. Informed consent for collection and use

Results

The characteristics of the baseline cohort are summarized in Table 1. Frailty as defined by CSBA index was present in more than one third of participants whereas, according to the mSOF index, only one tenth of the cohort was frail. Subjects identified as frail according to the CSBA index were older (79.6 ± 7.1 vs. 71.7 ± 5.1 years, p < 0.001), more frequently men (52.0% vs. 40.1%, p < 0.001), and less educated (41.9% with ≤3 years of education vs. 30.7%, p < 0.001) than their non-frail counterparts.

Discussion

This study of an elderly population-based cohort supports the view that full-blow frailty is more common than pure physical vulnerability (Bergman et al., 2007). According to previous investigations, prevalence of frailty ranges from 7.2% to 25.7% when using the physical phenotype (Fried et al., 2001, Gill et al., 2006), but rises from 16% to 43% when using cumulative frailty indexes (Puts et al., 2005, Rockwood et al., 2005). Although comparisons are hampered by huge differences in

Conclusion

The data show that different approaches to frailty result in different estimates for the prevalence of individuals at risk and different predictive accuracy for the outcomes of interest. The data also support the hypothesis that a cumulative index based upon the principle of multidimensional geriatric assessment may provide a better estimation of frailty-related adverse health outcomes than a unidimensional index exclusively focused on muscular fitness. Replication and extension of our findings

Conflict of interest statement

None.

Acknowledgement

This work was supported by the Basic Oriented Research grant from the University of Bologna.

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