Frailty Before the ICU: Using Frailty Scores to Guide Escalation Without Turning Them Into Gatekeepers

Introduction

Frailty has evolved from being a concept largely confined to geriatric medicine into an essential component of decision making across multiple medical specialties. Hospitalists, intensivists, cardiologists, pulmonologists, nephrologists, oncologists, neurologists, and emergency physicians increasingly encounter older adults whose acute illnesses are superimposed on varying degrees of physiologic vulnerability. As populations age and the prevalence of multimorbidity continues to rise, frailty assessment has become an important tool for evaluating prognosis, anticipating complications, and guiding individualized care. Rather than reflecting chronological age alone, frailty captures the cumulative decline in physiologic reserve that reduces an individual’s ability to withstand acute stressors and recover from serious illness.

The integration of frailty assessment into routine clinical practice offers substantial benefits, particularly when managing critically ill older adults. Numerous studies have demonstrated that frailty is independently associated with increased risks of intensive care unit admission, prolonged hospitalization, functional decline, institutionalization, and mortality. Consequently, validated frailty instruments have become increasingly incorporated into clinical pathways to support risk stratification and facilitate communication among multidisciplinary teams. However, despite its growing importance, frailty assessment is not without limitations. When interpreted without appropriate clinical context, frailty scores may inadvertently become substitutes for individualized clinical reasoning, leading to therapeutic pessimism or inappropriate limitation of potentially beneficial interventions.

The fundamental question is no longer whether frailty influences outcomes before transfer to the intensive care unit. Its prognostic significance has been consistently demonstrated across diverse patient populations and healthcare settings. Instead, the more clinically relevant question is how internists and acute care physicians should appropriately integrate frailty information into complex decisions regarding escalation of care. This issue is particularly important in older adults presenting with acute conditions such as severe pneumonia, acute decompensated heart failure, acute kidney injury, gastrointestinal hemorrhage, sepsis, pulmonary embolism, ischemic or hemorrhagic stroke, life threatening arrhythmias, respiratory failure, or multiorgan dysfunction. In these situations, clinicians are often required to make time sensitive decisions regarding intensive monitoring, organ support, mechanical ventilation, renal replacement therapy, vasopressor administration, and admission to higher levels of care.

Frailty assessment provides valuable prognostic information by identifying patients with diminished physiologic reserve who may be more susceptible to complications during critical illness. Tools such as the Clinical Frailty Scale, Frailty Index, Edmonton Frail Scale, and Hospital Frailty Risk Score have demonstrated utility in predicting mortality, intensive care outcomes, hospital readmission, and long term functional recovery. Importantly, these instruments assess vulnerability rather than futility. A high frailty score indicates an increased likelihood of adverse outcomes but does not determine whether a patient will benefit from intensive medical intervention.

Clinical decision making therefore requires a balanced and individualized approach. Frailty scores should complement rather than replace comprehensive clinical evaluation. Decisions regarding intensive care unit admission should incorporate multiple factors, including the severity of the acute illness, the likelihood that the underlying condition is reversible, preexisting functional status, burden of chronic disease, cognitive function, baseline quality of life, and expected trajectory of recovery. Equally important are the patient’s goals of care, previously expressed preferences, advance directives, and discussions with family members or substitute decision makers. Consultation with intensivists and multidisciplinary teams remains essential when determining the appropriateness of critical care interventions.

Current international guidelines consistently emphasize that frailty should not be used as an isolated criterion for limiting treatment or denying access to intensive care. Although frailty contributes important prognostic information, rigid reliance on predefined score thresholds risks oversimplifying complex clinical situations and may inadvertently introduce age related or disability related bias into decision making. Patients with similar frailty scores may have markedly different underlying diseases, treatment responses, rehabilitation potential, and personal values. Consequently, frailty should be viewed as one component of a comprehensive assessment rather than a definitive determinant of treatment eligibility.

An individualized approach is particularly important because many acute conditions requiring intensive care are potentially reversible. Older adults with severe infections, acute heart failure exacerbations, gastrointestinal bleeding, or pulmonary embolism may experience substantial recovery following timely evidence based interventions despite underlying frailty. Conversely, some patients with relatively low frailty scores may have irreversible illnesses associated with poor prognoses. Clinical judgment therefore remains indispensable in distinguishing patients who are likely to benefit from aggressive treatment from those for whom intensive interventions may provide limited value.

Frailty assessment also serves an important role in facilitating shared decision making. Objective evaluation of physiologic vulnerability can support transparent conversations with patients and families regarding expected outcomes, risks of invasive therapies, potential for functional recovery, and realistic treatment goals. These discussions enable care plans that align medical interventions with patient values while avoiding both inappropriate treatment limitation and nonbeneficial escalation of care.

Beyond decisions regarding intensive care admission, recognition of frailty has important implications throughout hospitalization. Frail patients often benefit from early multidisciplinary management involving geriatricians, physiotherapists, occupational therapists, nutrition specialists, pharmacists, social workers, and palliative care teams. Early mobilization, optimization of nutrition, prevention of delirium, medication review, and discharge planning can reduce complications and improve functional outcomes. Thus, frailty assessment should inform broader care planning rather than serving solely as a prognostic instrument.

In summary, frailty has become an indispensable consideration in the management of acutely ill older adults across internal medicine and critical care. Its value lies in enhancing prognostic accuracy, informing individualized treatment planning, and supporting shared decision making. However, frailty scores should never function as automatic gatekeepers for intensive care or substitutes for thoughtful clinical evaluation. Contemporary evidence and professional guidance consistently advocate for a nuanced approach in which frailty assessment is integrated with clinical judgment, disease specific prognosis, reversibility of illness, patient preferences, and multidisciplinary expertise. Used appropriately, frailty assessment strengthens patient centered care while helping clinicians make balanced, ethically sound decisions regarding escalation of treatment in older adults with critical illness.

Why This Matters Now

Older adults account for a substantial proportion of ICU admissions, and many reach the ICU after a period of ward-based deterioration during which internists or subspecialists are the first clinicians to recognize the need for escalation. Decisions about vasopressors, noninvasive ventilation, intubation, renal replacement therapy, transfer to the ICU, or a trial of life-sustaining treatment may occur before the ICU team has fully assumed care.

ICU outcomes are also no longer evaluated only by survival to hospital discharge. Clinicians increasingly consider persistent critical illness, prolonged ventilation, delirium, new disability, cognitive impairment, discharge to a facility, caregiver burden, and the likelihood of returning to a life the patient would consider acceptable. Prospective studies of older adults have found that baseline frailty and functional trajectory are associated with subsequent disability, nursing home admission, and mortality after critical illness.

Frailty assessment helps bring these outcomes into the conversation. It gives clinicians a structured way to ask:

What was the patient’s physiologic reserve before the acute illness?

What type of recovery is reasonably plausible if the acute process is reversed?

What treatment burden would the patient accept for that possibility?

Shared decision-making requires more than asking about cardiopulmonary resuscitation. It involves communicating likely benefits, burdens, uncertainties, and potential functional outcomes while eliciting the patient’s values. When the patient lacks decision-making capacity, the surrogate’s role is to represent the patient’s known preferences and values or, when those are unknown, to apply an appropriate best-interest standard. Structured tools can facilitate these discussions, but they cannot ensure agreement or eliminate prognostic uncertainty.

What Frailty Is, and What It Is Not

Frailty is a state of reduced physiologic reserve and increased vulnerability to stressors. It is related to age, comorbidity, disability, cognition, nutrition, sarcopenia, and social vulnerability, but it is not identical to any one of them.

Chronologic age alone is a poor substitute for frailty assessment. A functionally independent 86-year-old who walks daily, manages medications, and has stable chronic disease is not clinically equivalent to a 72-year-old with recurrent falls, progressive weight loss, cognitive impairment, and dependence in basic activities of daily living.

Frailty is also not synonymous with disability. A person with a stable long-term disability may require assistance with daily activities without having the same progressive multisystem vulnerability represented by frailty. The Clinical Frailty Scale has not been broadly validated in younger people or in people with stable, single-system disabilities. Mechanical application in these populations can distort prognosis and create inequity.

The Clinical Frailty Scale: Useful, Fast, and Easy to Misuse

The Clinical Frailty Scale is widely used in acute and critical care because it is brief, clinically intuitive, and based on global judgment of baseline function, comorbidity, cognition, and fitness. The original scale was developed from the Canadian Study of Health and Aging and was subsequently expanded from seven to nine categories.

For internists, the scale is useful because it can be completed relatively quickly during escalation discussions. It must be scored according to the patient’s baseline state before the acute illness, not according to how the patient appears during hypoxia, shock, delirium, acidosis, respiratory distress, or sedative exposure. In acute care, the patient’s status approximately two weeks before the illness is commonly used as a practical reference point when reliable information is available.

Baseline status should be corroborated whenever possible through patients, family members, caregivers, facility staff, home health clinicians, prior clinical notes, and objective indicators. Relevant information includes mobility, medication management, instrumental and basic activities of daily living, cognition, falls, recent hospitalizations, weight loss, and functional trajectory over the preceding months.

The Clinical Frailty Scale is a structured estimate of vulnerability and a prognostic aid. It is not a deterministic prediction instrument, a treatment-withholding rule, or a stand-alone allocation score. The scale requires clinical judgment, and its reliability depends on training and access to accurate baseline information.

Current Evidence: What Frailty Predicts

Frailty is associated with worse outcomes across acute care and ICU populations. Observational studies and meta-analyses have linked frailty with short-term and long-term mortality, post-ICU disability, new nursing home admission, and a lower likelihood of returning to baseline function. Frailty often adds clinically useful information beyond age alone, although it does not eliminate prognostic uncertainty.

A 2023 individual-patient meta-analysis included 23,989 nonelective ICU patients from 12 studies. In adults aged 65 years or older, frailty measured by the Clinical Frailty Scale was independently associated with ICU mortality after adjustment for age, sex, and illness acuity. In the overall pooled population, however, frailty was not independently associated with ICU mortality after adjustment. These findings support the CFS as a prognostic marker in older adults, but they do not establish a rigid threshold for ICU exclusion. Categories overlap, acute illness severity remains central, and observational data cannot determine whether withholding or providing ICU treatment caused the observed outcomes.

The ICE-CUB 2 cluster-randomized trial is also relevant. The trial enrolled adults aged 75 years or older who presented to French emergency departments with critical illness. The population was selected to exclude active cancer and severe baseline functional or nutritional impairment. A program promoting systematic ICU admission increased ICU use but did not reduce adjusted six-month mortality compared with usual practice. Functional status and physical quality of life at six months were not significantly different between groups. The trial does not show that ICU care is futile in older adults. It shows that increasing ICU admission across a selected older population does not automatically improve outcomes and that individual assessment remains necessary.

Post-ICU studies reinforce the importance of baseline status. Premorbid frailty and disability are associated with increased risks of death, new disability, nursing home admission, and incomplete functional recovery after critical illness. These outcomes may matter to patients as much as survival, but their relative importance must be elicited rather than assumed.

Guideline Context

The 2026 Society of Critical Care Medicine guideline on caring for older adults in the ICU conditionally suggests a geriatric model of care for all older adults admitted to the ICU. It also suggests not using antipsychotic medications to prevent delirium in older critically ill adults. Both recommendations were based on very low-certainty evidence. The guideline makes no recommendation for or against antipsychotic use to treat delirium in older critically ill adults because of insufficient evidence.

This guideline context shifts the role of frailty away from gatekeeping and toward geriatric-informed care. Relevant domains include baseline function, delirium prevention, cognition, medication review, mobility, communication, family engagement, patient-centered outcomes, and recovery planning.

The 2026 SCCM guideline on allocating critical care resources during crisis-level shortages found insufficient evidence to recommend using a formal triage tool rather than no formal tool when ICU capacity is limited. The panel issued one conditional recommendation and five no-recommendation statements, reflecting the limited certainty of the evidence. In ordinary clinical practice, a frailty score should not function as a hidden rationing mechanism. During declared crisis conditions, triage decisions require transparent institutional policies, ethical oversight, multidisciplinary governance, and safeguards against inequity.

The 2025 SCCM adult end-of-life ICU guideline conditionally suggests using structured tools to facilitate shared decision-making. It also supports standardized processes for identifying legal surrogate decision-makers, proactive palliative care or ethics consultation when appropriate, and institutional policies for conflicts involving potentially inappropriate treatment. These recommendations align with frailty-informed escalation planning but do not make frailty a criterion for treatment withdrawal.

Practical Approach for Internists Before ICU Escalation

Frailty assessment is most useful when an escalation decision is preference-sensitive and prognosis or treatment responsiveness is uncertain. It may be less immediately useful when ICU treatment is clearly indicated for an acutely reversible process or when the patient’s previously established goals already specify a comfort-focused ceiling of life-sustaining treatment.

Urgent stabilization should not be delayed to complete a frailty score. Oxygen, antimicrobials, fluids, vasopressors, noninvasive ventilation, transfusion, source control, rhythm management, and other time-sensitive interventions should proceed when clinically indicated. Frailty assessment should add context, not create dangerous inertia.

Table 1. Frailty-Informed Escalation Assessment

Domain	Key question	Practical approach
Baseline status	What was the patient like before this illness?	Assess mobility, ADLs, cognition, falls, nutrition, and recent functional trajectory. Do not score current shock, hypoxia, or delirium as baseline frailty.
Frailty estimate	Would a structured estimate add useful information?	Use the CFS or another validated local instrument in trained hands. Do not treat the result as an ICU admission rule.
Acute reversibility	Is the acute process potentially treatable?	Identify infection, bleeding, obstruction, arrhythmia, toxicity, ischemia, or volume disturbance. Do not equate frailty with futility.
Patient goals	Which outcomes would the patient value or refuse?	Discuss ventilation, dialysis, vasopressors, cognition, dependence, functional recovery, and acceptable treatment burden.
Escalation plan	What intensity is proportionate to prognosis and goals?	Consider ICU transfer, a treatment ceiling, palliative focus, or a time-limited trial with explicit reassessment criteria.

A frailty-informed escalation note should be concise but explicit. It should document baseline physical and cognitive function, the frailty estimate and supporting evidence, the acute diagnosis, assessment of reversibility, patient or surrogate goals, proposed treatment intensity, and the planned reassessment interval.

A practical note might read:

“Baseline CFS estimated at 6 based on dependence for outdoor activities and some personal care, with progressive decline over six months. Current deterioration appears related to potentially reversible pneumonia and volume overload. The patient previously prioritized returning home and avoiding prolonged mechanical ventilation. ICU consultation requested for possible noninvasive ventilation and vasopressor-capable monitoring, with reassessment in 24 to 48 hours based on oxygenation, shock resolution, renal function, delirium trajectory, treatment burden, and patient-centered goals.”

Patient Selection and Risk Stratification

Frailty should be integrated with acute physiology, disease-specific prognosis, reversibility, comorbidity burden, cognition, nutrition, social support, and patient goals. It should not be interpreted as a universal contraindication to ICU care or specialty-specific treatment.

Consider a patient with advanced heart failure and moderate frailty who presents with acute decompensation. If the episode appears related to a potentially reversible trigger, such as infection or atrial fibrillation with rapid ventricular response, and the patient’s goals support an attempt at recovery, ICU-level treatment may remain appropriate. Frailty contributes to the assessment of recovery potential, but it cannot independently determine whether the patient will recover.

In advanced heart failure or severe valvular disease, frailty should be considered alongside acute hemodynamics, cardiac disease severity, end-organ dysfunction, prior trajectory, reversibility, and response to initial treatment.

In chronic obstructive pulmonary disease, interstitial lung disease, pulmonary hypertension, or neuromuscular respiratory failure, frailty assessment may support conversations about noninvasive ventilation, intubation, likelihood of ventilator liberation, tracheostomy, rehabilitation needs, and post-ICU function.

In kidney disease, frailty may inform discussions about urgent renal replacement therapy as a bridge through a reversible illness compared with dialysis as a possible new long-term burden in a patient with severe functional decline.

In cirrhosis, malignancy, and immune-mediated disease, frailty should be considered alongside disease-specific prognostic tools, transplant or disease-modifying treatment candidacy, medication toxicity, infection risk, treatment response, and patient priorities.

The role of frailty is not to deny therapy when a medically reasonable path to recovery aligns with the patient’s values. Its role is to make the expected benefits, burdens, uncertainty, and endpoints of escalation more explicit.

Time-Limited Trials: A Potentially High-Value Use of Frailty Assessment

A time-limited trial may be a practical option when the prognosis or response to intensive treatment is uncertain and the patient or surrogate is willing to proceed with a defined period of life-sustaining therapy. It is neither an agreement to provide every treatment indefinitely nor a covert decision to withhold care.

An American Thoracic Society workshop defined a time-limited trial as a collaborative plan among clinicians and a patient or surrogate to use life-sustaining therapy for a defined duration, after which the patient’s response informs whether to continue recovery-directed treatment, transition to comfort-focused care, or extend the trial. The report identified important evidence gaps and cautioned that poorly implemented trials may create unintended harm.

For a frail patient with potentially reversible sepsis, a trial might include antimicrobial therapy, source control, vasopressors, respiratory support, or intubation when consistent with the patient’s goals. Reassessment could address shock resolution, oxygenation, neurologic trajectory, renal recovery, vasopressor requirements, source control, treatment burden, and signs that recovery remains clinically plausible.

Specificity is essential. A meaningful plan defines the treatment goal, expected time course, measurable indicators of improvement or deterioration, and the decisions that may follow reassessment. The phrase “we will see how things go” does not constitute a time-limited trial.

Table 2. Elements of a Time-Limited ICU Trial

Element	Bedside question	Example
Treatment goal	What process are we trying to reverse?	Septic shock, pulmonary edema, hyperkalemia, or gastrointestinal bleeding
Duration	When will formal reassessment occur?	At 24, 48, or 72 hours, adjusted to the expected illness trajectory
Milestones	What findings would support continuation?	Lower vasopressor need, improved oxygenation, source control, or renal recovery
Warning signs	What findings would reduce the likelihood of an acceptable recovery?	Progressive multiorgan failure, refractory shock, or worsening neurologic status
Decision pathway	What options follow reassessment?	Continue treatment, modify the trial, revise the treatment ceiling, or transition to comfort-focused care

Medication and Safety Considerations

Frailty assessment should prompt a structured medication review during acute illness. Frail older adults may be more vulnerable to delirium, falls, hypotension, renal adverse effects, drug accumulation, drug interactions, oversedation, and deconditioning. Medication review should include sedatives, anticholinergic drugs, opioids, antipsychotics, antihypertensives, anticoagulants, glucose-lowering agents, and renally cleared medications.

The 2026 SCCM guideline suggests not using antipsychotic medications for delirium prevention in older critically ill adults and makes no recommendation for or against their use to treat delirium. The absence of a treatment recommendation should not be interpreted as evidence of benefit. When an antipsychotic is considered for severe agitation that creates an immediate safety risk or prevents essential care, the decision should be individualized and time-limited. Reversible causes, pain, medication effects, sleep disruption, sensory impairment, urinary retention, constipation, and environmental factors should be addressed. Agent-specific contraindications, interactions, warnings, and monitoring requirements should be reviewed before prescribing.

Frailty alone is not a medication contraindication. It is a signal to individualize treatment selection and dosing, reassess necessity, monitor closely, and avoid regimens in which pharmacologic burden is likely to exceed expected benefit.

Ethical and Communication Considerations

Frailty assessment can support more consistent attention to baseline function and physiologic reserve. It can also undermine fairness if it is applied unevenly, used without training, or interpreted as a proxy for age, disability, social worth, or a clinician’s perception of quality of life.

Several safeguards are essential. Clinicians should distinguish progressive frailty from stable disability, avoid rigid cutoffs, document the reasoning behind escalation decisions, involve patients or surrogates early, and interpret frailty alongside acute severity, reversibility, comorbidities, disease-specific treatment options, and patient values.

The ethical question is not simply, “Is this patient frail?” The more appropriate questions are, “Which treatments are medically reasonable?”, “What outcomes are realistically achievable?”, and “Which outcomes and treatment burdens would this patient consider acceptable?”

Table 3. Common Misuses of Frailty Scores and Safer Alternatives

Misuse	Why it is problematic	Safer alternative
“CFS 5 or higher means no ICU.”	No validated universal cutoff establishes absence of benefit, and rigid use risks undertreatment and discrimination.	Use frailty as one factor alongside acuity, reversibility, disease-specific prognosis, and patient goals.
Scoring the patient’s current appearance	Acute illness, delirium, sedation, hypoxia, and shock may mimic or exaggerate frailty.	Estimate premorbid baseline using collateral information and prior records.
Equating disability with frailty	Stable disability does not necessarily imply progressive physiologic vulnerability or poor ICU prognosis.	Assess trajectory, reserve, cognition, comorbidity, and reversibility.
Asking only about code status	CPR preferences do not define the patient’s preferences regarding ventilation, vasopressors, dialysis, or prolonged dependence.	Discuss specific interventions and possible functional and cognitive outcomes.
Beginning open-ended ICU treatment without reassessment	Treatment may continue without agreement about goals, milestones, or acceptable burdens.	Define treatment goals, measurable milestones, and a reassessment interval.

Limitations of the Evidence

The evidence base is clinically important but imperfect. Many frailty studies are observational, heterogeneous, and vulnerable to confounding. Frailty can influence treatment decisions, and those decisions can influence observed outcomes. Treatment-selection effects make it difficult to separate baseline vulnerability from the consequences of providing, limiting, or withholding intensive treatment.

Frailty instruments also differ in their conceptual frameworks and applications. The Fried phenotype focuses primarily on physical criteria, including weakness, slowness, low activity, exhaustion, and unintentional weight loss. A frailty index measures accumulated health deficits. The Clinical Frailty Scale uses global clinical judgment that incorporates function, comorbidity, cognition, and fitness. Other instruments, including the Edmonton Frail Scale, Hospital Frailty Risk Score, and electronic frailty measures, capture overlapping but nonidentical constructs.

The Clinical Frailty Scale is practical in acute care, but its accuracy depends on appropriate training, reliable premorbid information, and clinical judgment. Inter-rater variability and misclassification remain possible, particularly when documentation is limited or acute illness is mistakenly treated as the patient’s baseline.

Outcome selection is another limitation. Many studies emphasize mortality, while patients may place equal or greater importance on cognition, function, independence, discharge destination, caregiver burden, and the possibility of returning to a meaningful life. Some patients may consider survival with severe cognitive or functional impairment inconsistent with their goals. Clinicians should not presume that preference. It should be elicited directly or interpreted through the patient’s previously expressed values.

Future Directions

Future research should clarify how frailty assessment changes clinical decisions, not only how it predicts outcomes. Studies should examine whether and how frailty-informed pathways affect clinician recommendations, patient and family understanding, shared decision-making, ICU utilization, functional outcomes, disparities, and goal-concordant care.

Implementation research should evaluate whether structured communication tools, interdisciplinary rounds, geriatric consultation, rehabilitation planning, and clinical decision support improve prognostic understanding or reduce potentially nonbeneficial treatment without restricting access to beneficial care.

Hospitals should train non-geriatric clinicians to score frailty consistently and communicate findings without implying futility. Electronic health record integration may help when it supports clinical reasoning and documentation, but it may cause harm if it creates automated treatment exclusions or unexamined score-based thresholds.

The next step is not to make frailty a gatekeeper. It is to make frailty part of a more honest, individualized, and outcome-oriented approach to escalation.

References

1. Bruno, R. R., Wernly, B., Bagshaw, S. M., van den Boogaard, M., Darvall, J. N., De Geer, L., et al. (2023). The Clinical Frailty Scale for mortality prediction of old acutely admitted intensive care patients: A meta-analysis of individual patient-level data. Annals of Intensive Care, 13(1), 37. https://doi.org/10.1186/s13613-023-01132-x. PMID: 37133796.
2. Church, S., Rogers, E., Rockwood, K., & Theou, O. (2020). A scoping review of the Clinical Frailty Scale. BMC Geriatrics, 20(1), 393. https://doi.org/10.1186/s12877-020-01801-7. PMID: 33028215.
3. Clegg, A., Young, J., Iliffe, S., Olde Rikkert, M., & Rockwood, K. (2013). Frailty in elderly people. The Lancet, 381(9868), 752-762. https://doi.org/10.1016/S0140-6736(12)62167-9. PMID: 23395245.
4. Dalhousie University Geriatric Medicine Research. (n.d.). Clinical Frailty Scale. Retrieved July 25, 2026, from https://www.dal.ca/sites/gmr/our-tools/clinical-frailty-scale.html 
5. De Biasio, J. C., Mittel, A. M., Mueller, A. L., Ferrante, L. E., Kim, D. H., & Shaefi, S. (2020). Frailty in critical care medicine: A review. Anesthesia & Analgesia, 130(6), 1462-1473. https://doi.org/10.1213/ANE.0000000000004665. PMID: 32384336.
6. Devlin, J. W., Skrobik, Y., Gélinas, C., Needham, D. M., Slooter, A. J. C., Pandharipande, P. P., et al. (2018). Clinical practice guidelines for the prevention and management of pain, agitation/sedation, delirium, immobility, and sleep disruption in adult patients in the ICU. Critical Care Medicine, 46(9), e825-e873. https://doi.org/10.1097/CCM.0000000000003299. PMID: 30113379.
7. Ferrante, L. E., Chaudhuri, D., Laiya Carayannopoulos, K., Jain, S., Tate, J. A., Álvarez-Espinoza, E., et al. (2026). Society of Critical Care Medicine guidelines on caring for older adults in the ICU. Critical Care Medicine, 54(5), 1060-1072. https://doi.org/10.1097/CCM.0000000000007085. PMID: 41860322.
8. Ferrante, L. E., Pisani, M. A., Murphy, T. E., Gahbauer, E. A., Leo-Summers, L. S., & Gill, T. M. (2015). Functional trajectories among older persons before and after critical illness. JAMA Internal Medicine, 175(4), 523-529. https://doi.org/10.1001/jamainternmed.2014.7889. PMID: 25665067.
9. Ferrante, L. E., Pisani, M. A., Murphy, T. E., Gahbauer, E. A., Leo-Summers, L. S., & Gill, T. M. (2018). The association of frailty with post-ICU disability, nursing home admission, and mortality: A longitudinal study. Chest, 153(6), 1378-1386. https://doi.org/10.1016/j.chest.2018.03.007. PMID: 29559308.
10. Fried, L. P., Tangen, C. M., Walston, J., Newman, A. B., Hirsch, C., Gottdiener, J., et al. (2001). Frailty in older adults: Evidence for a phenotype. The Journals of Gerontology: Series A, 56(3), M146-M156. https://doi.org/10.1093/gerona/56.3.M146. PMID: 11253156.
11. Guidet, B., Leblanc, G., Simon, T., Woimant, M., Quenot, J. P., Ganansia, O., et al. (2017). Effect of systematic intensive care unit triage on long-term mortality among critically ill elderly patients in France: A randomized clinical trial. JAMA, 318(15), 1450-1459. https://doi.org/10.1001/jama.2017.13889. PMID: 28973065.
12. Kim, D. H., & Rockwood, K. (2024). Frailty in older adults. The New England Journal of Medicine, 391(6), 538-548. https://doi.org/10.1056/NEJMra2301292. PMID: 39115063.
13. Kon, A. A., Davidson, J. E., Morrison, W., Danis, M., & White, D. B. (2016). Shared decision making in intensive care units: An American College of Critical Care Medicine and American Thoracic Society policy statement. Critical Care Medicine, 44(1), 188-201. https://doi.org/10.1097/CCM.0000000000001396. PMID: 26509317.
14. Kruser, J. M., Ashana, D. C., Courtright, K. R., Kross, E. K., Neville, T. H., Rubin, E., et al. (2024). Defining the time-limited trial for patients with critical illness: An official American Thoracic Society workshop report. Annals of the American Thoracic Society, 21(2), 187-199. https://doi.org/10.1513/AnnalsATS.202310-925ST. PMID: 38063572.
15. Lewis, K., Balas, M. C., Stollings, J. L., McNett, M., Girard, T. D., Chanques, G., et al. (2025). A focused update to the clinical practice guidelines for the prevention and management of pain, anxiety, agitation/sedation, delirium, immobility, and sleep disruption in adult patients in the ICU. Critical Care Medicine, 53(3), e711-e727. https://doi.org/10.1097/CCM.0000000000006574. PMID: 39982143.
16. Marshall, M. F., Davis, F. D., Fogelman, P. A., Oczkowski, S., Reid, J. C., Arellano, D., et al. (2025). Society of Critical Care Medicine clinical practice guidelines on adult end-of-life care in the ICU. Critical Care Medicine, 53(12), e2734-e2746. https://doi.org/10.1097/CCM.0000000000006856. PMID: 41342842.
17. Nates, J. L., Jayaprakash, N., Laiya Carayannopoulos, K., Honarmand, K., Anesi, G. L., Davis, L. B., et al. (2026). Society of Critical Care Medicine guidelines for the allocation of critical care resources to adults during crisis-level shortages. Critical Care Medicine, 54(3), 619-629. https://doi.org/10.1097/CCM.0000000000006998. PMID: 41773927.
18. NICE Critical Care. (n.d.). Frailty. Retrieved July 25, 2026, from https://www.criticalcarenice.org.uk/frailty 
19. Rockwood, K., Song, X., MacKnight, C., Bergman, H., Hogan, D. B., McDowell, I., & Mitnitski, A. (2005). A global clinical measure of fitness and frailty in elderly people. CMAJ, 173(5), 489-495. https://doi.org/10.1503/cmaj.050051. PMID: 16129869.
20. Rockwood, K., & Theou, O. (2020). Using the Clinical Frailty Scale in allocating scarce health care resources. Canadian Geriatrics Journal, 23(3), 210-215. https://doi.org/10.5770/cgj.23.463. PMID: 32904824.