Frailty is without question one of the most serious global public health challenges we will face this coming century. The rapid expansion of the ageing population has brought a concomitant rise in the number of older adults with frailty,1, 2 which in turn places an increased pressure on health-care systems worldwide.3 Unfortunately, older people with frailty have an increased likelihood of unmet care needs, falls and fractures, hospitalisations, lowered quality of life, iatrogenic complications, and early mortality.4, 5, 6, 7, 8, 9 This increased risk of adverse outcomes can occur even without the presence of comorbidities.4 Therefore, effective strategies that target the prevention and management of frailty in an ageing population will probably reduce the condition's burden at the level of both the individual and the health system.
In reflection of increased research interest, the term frailty was introduced as a PubMed Medline Search Heading (MeSH) in January, 2018. Frailty is recognised as an age-related clinical condition10, 11, 12 that is typically observed by a deterioration in the physiological capacity of several organ systems,4, 8, 12, 13 and that causes an increased susceptibility to stressors.4, 7, 8, 10, 11, 12 When stressor events (such as acute illness) occur, a person with frailty rapidly deteriorates in functional capacity. Thus, interventions to prevent or slow the progression of frailty before it leads to substantial functional decline are key concerns for health-care policy and provision.
In general, frailty is recognised as the physical state that exists before occurrence of disability,7, 8 although it is possible for frailty and disability to coexist.14 Frailty is also a dynamic entity that exists on a continuum from fit to frail,4, 13, 15 wherein an individual's level of frailty is able to change in either direction over time.7 Correspondingly, frailty is potentially reversible7, 8 and its associated functional decline is also a potentially preventable disability.16 In many cases, frailty onset starts before age 65 years, although not all adults develop frailty, even at advanced ages.4 Notably, the use of frailty measurements for the purposes of prognosis has recently emerged from geriatric medicine and into the medical specialties.9, 17, 18, 19 What this means is that recognition of an individual's frailty status can inform treatment decisions, goals of care, and recovery expectations.20
Key messages
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Although presence of frailty might seem like an ideal way to identify people who need additional support services, there is a shortage of substantial research evidence to support this strategy and to identify the most effective instruments to detect frailty
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In clinical practice, the management of an older adult with frailty is complex because of the inadequate evidence base for individual and health-system interventions to manage the condition
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We need to accrue more knowledge about which intervention strategies are effective for frailty, and to determine whether they are feasible and cost-effective
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High quality clinical trials are needed that take into account the perspectives and needs of health-care providers, older people with frailty, and their carers
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In the absence of a firm evidence base for interventions, strategies to manage frailty in daily practice can be based on existing consensus guideline recommendations
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It is important that frailty does not become a new aspect of ageism that prevents access to interventions that could be appropriate
Over the past two decades, strategies to manage frailty have progressed substantially. However, to progress from traditional, episodic-based care to more proactive, person-centred care, we need to do much more. In this Series paper, we provide a critical review of the evidence base behind both individual and health-care system interventions targeting individuals with frailty. With a noticeable lack of high-quality research evidence regarding how best to identify and treat people with frailty, we provide a research-informed viewpoint of what strategies appear to work best. We acknowledge that although frailty can occur in people of all ages (particularly if comorbidities are present), the majority of intervention trials involve older populations. Hence, the focus of our review is on older adults, although findings might also be applicable to younger people with frailty. This paper is the second in this Series on frailty, with the first paper overviewing the concept of frailty, as well as its global burden, life-course perspective, and potential targets for prevention. An outline of terminology used in this Series is shown in panel 1. For this review, we consider frailty as distinct from advanced age, functional ability, and multimorbidity, even though it is related to these concepts.