What is frailty?

Frailty is a state of high vulnerability for adverse health outcomes, including disability, dependency, falls, need for long-term care, and mortality. This condition is associated with geriatric symptoms such as sarcopenia, cognitive impairment and dementia. Whilst it is more frequent in older age, it is not synonymous with old age and should, therefore, be considered separately.

Frailty is characterised by the loss of biological reserves and heightens a patient’s vulnerability to adverse health outcomes, hospitalisation, long-term dependency and mortality. Thus, recognising frailty in the clinical setting is crucial and necessitates a tailored approach [1, 2].

Frailty is identified through a comprehensive assessment of medical, cognitive and functional problems that aims to look at the patient’s physiological reserve, identify and manage long-term health conditions, identify goals and ultimately develop a personalised treatment and support plan. This syndrome, a consequence of cumulative decline across multiple physiological systems, poses significant challenges in healthcare, particularly in acute settings such as the intensive care unit (ICU). Understanding the nuances of frailty and how to measure, it is critical to improving patient management and outcome [3]. The tool used to measure frailty should be easy to understand, collect, and show good agreement amongst users. The Clinical Frailty Scale (CFS) is probably the most suitable tool in urgent situations [2].

Comorbidities vs. frailty

Frailty and comorbidities, whilst interrelated, are distinct concepts. The term comorbidity is used when a patient has two or more chronic diseases, whereas frailty is a state of increased vulnerability resulting from decreased physiological reserves. Comorbidities can exacerbate the severity of frailty, making management more complex. For example, chronic diseases such as diabetes or heart failure may accelerate a decline in physical function, a key component of frailty. It is essential that healthcare providers distinguish between the two to ensure appropriate treatment plans are in place. However, comorbidities are often neither sensitive nor specific. For instance, two 75-year-old patients with diabetes and high blood pressure may have the same comorbidities. However, one may be independent and very active, whilst the other dependent on their family for daily activities. Thus, their frailty status is very different, as are their chances of survival and recovery following critical illness.

Age vs. frailty: old and fit vs. young and frail

Frailty is often mistakenly considered a synonym for old age [4,5,6,7,8,9]. However, older individuals can remain fit and robust, whilst younger individuals may exhibit signs of frailty due to various factors, including chronic illnesses or lifestyle choices. Comparisons between older fit individuals and younger frail individuals reveal that frailty, not age, is a more critical determinant of patient outcome. Whilst it is more prevalent in those aged 65 and older, frailty can also be present in younger patients [10], and even in this age group, it is a better predictor of long-term outcome than age alone.

In very old patients, frailty has significant prognostic value. In patients aged 80 and above, frailty is strongly associated with prognosis, with lower degrees associated with better ICU, hospital, and longer term outcomes. In the VIP 2 study in critically ill patients aged 80 and above, age was not significantly associated with mortality after correction for confounders such as frailty [4]. In summary when managing frail patients, age should be considered, but encompassed within the overall assessment. Individualised care plans should be developed, considering the patient’s overall health status rather than relying solely on chronological age.

The concept of physiological reserve, frailty, and clinical trajectory in ICU

The concept of physiological reserve is pivotal in understanding frailty in ICU patients. Physiological reserve refers to the body's ability to withstand stress and recover from illness. This reserve is significantly diminished in frail patients, affecting their clinical trajectory and outcome. In practice, the higher the frailty and lower the physiological reserve at baseline, the lower the probability of making a full recovery after critical illness and the higher the chance the patient will either die or recover with significant morbidity and dependency. Long-term outcomes such as a diminished quality of life, persistent functional impairment, or increased mortality rates are more frequently seen in frail patients [11].

However, one should carefully look at the clinical response to organ support as a proxy for longer term outcomes. There is no evidence that the initial response is associated with a better or worse outcome [12].

The baseline physiological reserve, measured by frailty, is a more important prognostic factor.

However, in practice, whilst a decision to admit a patient or not based on their chance of recovery can be informed by these factors, once a patient is admitted to intensive care, there is little to no evidence that the treatment received is based on their pre-ICU frailty status. It is also true that since frail patients are less likely than fit patients to survive critical illness, limitations of life-sustaining treatment occur more frequently amongst frail patients compared to fit.

Therefore, the relationship between frailty and the need for organ support is complex. This understanding underscores the importance of a nuanced approach to the management of frail patients in the ICU, balancing ICU admission and aggressive interventions against the potential for benefit and harm. In these situations when there is uncertainty, a time limited trial can be implemented to improve predictive accuracy whilst minimising the patient’s exposure to potentially harmful therapies [13].

Frailty and ICU admission criteria

Frailty profoundly influences decision-making regarding ICU admission. Admission criteria need to address a frail patient’s specific needs and challenges adequately. Frailty assessments should be integrated into the admission process to better evaluate the patient’s suitability for ICU care. Such assessments can help guide healthcare providers to make more informed decisions about the potential benefits and risks of an ICU admission for frail individuals. In the acute setting, when a decision to admit to ICU or not is urgent, it is not possible to perform a comprehensive geriatric assessment as this takes time and requires a co-operative patient. Therefore, other tools such as the CFS are frequently used. This is a visual scale composed of nine categorise progressing from fit (CFS 1) to terminally ill (CFS 9).

Ultimately, the decision to admit a frail patient to the ICU should be based on clinical indications and the patient’s shared and informed goals of care, quality of life considerations, and potential long-term outcomes. Incorporating frailty assessments into ICU admission criteria can improve resource utilisation, patient outcomes, and enhance ethically sound decision-making.

Different patient groups: medical vs. surgical, multidimensional frailty data

The impact of frailty on ICU outcomes can vary significantly between medical and surgical patients. Frail surgical patients have higher risks of postoperative complications and longer recovery times. Thus, a frailty assessment prior to an operation may help to identify those patients who may benefit from elective postoperative ICU care to maximise their chance of recovery and minimise their chance of developing postoperative complications.

Multidimensional frailty scores have recently been demonstrated to better predict postoperative outcomes than classic American Society of Anaesthesiologists (ASA) scores [14].

Recent data on old frail patients during the coronavirus disease 2019 (COVID-19) pandemic have highlighted the vulnerability of frail patients to severe outcomes and confirmed the validity of this concept even when a new disease arises [15].

Informing and explaining frailty to patients and families

Communicating information about frailty with patients and their families is critical. Effective communication involves explaining the concept of frailty, its implications for treatment and outcomes, and the rationale behind management decisions. Engaging in a clear, compassionate dialogue that respects the patient's values and preferences is essential. Informed consent and shared decision-making are crucial in managing frail patients, especially when considering interventions with significant risks and benefits. Healthcare providers should strive to build a trusting relationship with patients and their families, facilitating a shared understanding of frailty and its impact on treatment decisions.

Take-home message

In conclusion, understanding and managing frailty in the ICU is a complex, multidimensional challenge (Fig. 1).

Figure 1
figure 1

Multimodal approach to assessing and managing frail patients in intensive care

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ICU professionals must understand frailty, from its definition and differentiation from ageing and comorbidities to its impact on ICU admission criteria and patient outcome. The nuances of frailty in medical and surgical ICU patients, including insights from recent COVID-19 data, highlight the need for a specialised approach to care. Effective communication with patients and their families is essential in navigating the complexities of frailty. Future research should continue to explore the intricacies of frailty in critical care, aiming to refine assessment tools, improve patient care strategies, and enhance outcomes for this vulnerable population.