Frailty in older adults: Findings from longitudinal studies

Abstract

Frailty is common among older adults and represents a state of decreased physiological reserve which places individuals at risk of increased vulnerability to adverse outcomes such as falls, hospitalisation, residential care admission, and mortality. Frailty is a dynamic condition where improvement is possible and remaining stable is common. Furthermore, interventions exist that may delay or reverse frailty. There are two main approaches to describing frailty: the frailty phenotype (FP), which is based on a pre-defined set of physical characteristics of frailty, and the accumulation of deficits approach. In the deficits approach, the proportion of deficits, across a wide range of body systems and health conditions, is identified in an individual and represented as a frailty index (FI). Internationally, there is a large and growing body of research focused on frailty. However, there are a limited number of Australian population-level studies of frailty prevalence, factors associated with frailty, and the diagnostic value of screening instruments for frailty. Less attention has been focused internationally on a comparison of the two approaches to frailty measurement, the natural course of frailty, its co-presence with sarcopenia (a loss of lean muscle mass and function), and minimally important difference in frailty, which is the smallest change in a treatment outcome which an individual would perceive as being important. The aims of this thesis were therefore to: identify the prevalence of frailty at a population level and determine factors associated with frailty examine the transitions between frailty states and to describe the characteristics associated with frailty status improving, remaining stable, or worsening identify the diagnostic test accuracy (DTA) of self-reported screening instruments against a frailty reference standard for community dwelling older adults in a systematic review determine the predictive ability of frailty classification, and the effect of recency of frailty measurement, on mortality prediction also examine the predictive ability of sarcopenia alone and sarcopenia in combination with frailty on mortality examine the predictive validity of the FRAIL Scale and the SARC-F, self-reported screening instruments for frailty and sarcopenia respectively determine the relationship between frailty status and health-state utility and to determine a minimally important difference for frailty measures. Research from this doctoral thesis has confirmed that frailty is common among community dwelling older adults in Australia and it is associated with a range of health and socioeconomic determinants. Findings have also demonstrated that improvement in frailty classification is possible and that remaining stable is common. The dynamic nature of frailty was further highlighted in our findings, which demonstrated the importance of repeated frailty measurement for improved mortality prediction. Additionally, frailty and sarcopenia in combination result in worse survival outcomes. We have also demonstrated the predictive validity of self-reported screening instruments for both frailty and sarcopenia, and that frailty is associated with lower health-state utility. In terms of conducting assessments for frailty, we have identified values for minimally important differences for both methods of frailty measurement. These findings have important clinical implications for both the identification and management of frail individuals, and for promoting healthy ageing through offering preventative strategies. A key message from this thesis for health practitioners and older adults is that despite frailty being common, it can be either prevented, reversed, or delayed, and that a regular review of frailty status is important for targeting interventions as required, and maximising quality of life.