Clinical uses and alternative approaches of frailty determination

Kenneth L Seldeen ^1,2* John A Batsis ^3,4

• ¹ University of Kansas Medical Center, Kansas City, Kansas, United States
• ² Kansas City VA Medical Center, United States Department of Veterans Affairs, Kansas City, Missouri, United States
• ³ Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
• ⁴ University of North Carolina System, Chapel Hill, North Carolina, United States

Frailty represents a greater vulnerability to stressors that increases an individual's susceptibility to adverse health outcomes, including disability, loss of independence, and death. As one ages, frailty prevalence increases and affects as many as 50% of those 85 years of age and older [1]. Efforts to characterize and quantify states of frailty took a substantial leap forward with physical frailty and deficit accumulation-based frailty assessment frameworks that emerged in the early 2000's [2][3][4]. Since that time, frailty tools have been correlated to important health outcomes relevant to aging, have been used to evaluate therapeutic benefit, and are now being explored the help scientists understand the underlying biology of frailty [2,3,[5][6][7]. Importantly, frailty tools have also found utility in predicting outcomes for medical and surgical interventions and continue to be refined for helping improve prognostication among older individuals [8][9][10].The goal of this special issue is to identify alternative tools for the study of frailty. Tools for the rapid assessment of frailty have been reported, including the FRAIL scale [11], that can typically be completed in 2-3 minutes via a five-question survey. Alternatively, a single measure of grip strength or test of gait speed have also been strongly correlated with frailty and can represent an alternative [12,13]. However, in addition to clinical workflow issues, as frailty is a multi-factorial syndrome [14][15][16], the possibility exists that different tools may capture different aspects of frailty. This point is highlighted by a comparison of frailty tools in mice that identified differences between physical frailty and deficit accumulation assessment frameworks [17]. The collection contained within this special issue highlight unique tools for frailty as well as relationships to important physiologic parameters.The first article by Seldeen et al. [18], identifies correlations between VO2max, the 6-minute walk test, and arm strength (using a handheld dynamometer) and frailty for the first time in older Veterans. Of interest in this article was correlation was observed between VO2max and 6-minute walk, but not arm strength -suggesting the physical performance measures may capture different aspects of frailty (i.e., contribution of strength versus endurance). The next two articles advance different strategies in the use of the clinical frailty scale (CFS, [19]), a rapid frailty determination tool that scores patients on a 9-point scale based on functional capacity, co-morbidity status, and activity of daily living dependency [19][20]. The first, by Zacchetti et al. [21], examined and found the CFS predicts outcomes in older adults with moderate to severe traumatic brain injuries. In the study, these authors found patients identified as vulnerable (CFS ≥ 4) exhibited a staggering 87% mortality (versus 30% non-vulnerable) at 6-months -demonstrating the utility for risk stratification. The second by Garcia-Chanes et al. [22], employed an adaptation of the CFS that was designed to allow generation of a CFS score without the need of clinician input. Building from data within the Study on Global Aging and Health (SAGE, [23]), the authors incorporated answers from a wide variety of questions including activities of daily living, health status, day to day activities, self-reported data, etc., which then uses a classification tree to generate a score on a 7-point scale. Using this tool the authors identified an intricate relationship between frailty and cognitive performance. Both of these articles demonstrate alternative applications for an existing frailty framework that allow new utility for risk stratification and applicability to varied data sources.The fourth article in this special issue, Liu et al. [24], incorporates a simplified 5-item frailty score, generated from the presence of co-morbidities or need for assistance with activities of daily living, into a nomogram that can be used to predict 1-, 3-, and 5-year survival following radical nephroureterectomy. The validity of the model serves as proof-of-concept for the incorporation of frailty into outcome prediction for medical interventions. The last article in this issue, Eisenkraft et al. [25], examines a new detection and warning tool for timely alerts of real-time deterioration. The device used was a wireless, wearable chest patch monitor that measures every 5 minutes: heart rate, blood oxygen saturation, respiratory rate, blood pressure, body temperature, and several cardiac parameters. In the article the authors describe the new tool increased sensitivity versus the current tool with detection of impending health events nearly 9 hours earlier. The concepts described here involving wearable technologies might be applied to frailty detection in light of an estimated 20% of the United States population use fitness trackers [26].The wide range of strategies presented within this special issue to characterize frailty overall reflect the multi-factorial nature of frailty. Likewise, such tools may also be useful in characterizing resilience, the ability to respond to and recover from physical and cognitive stresses that challenge homeostasis and the "characteristic which determines one's ability to resist or recover from functional decline following health [27,28]" (e.g., falls, hip fracture, surgery, hospitalization, etc.). Poor resilience likely precedes frailty and thus must be maintained for optimal functional capacity, healthspan, and quality of life [29][30][31][32][33][34][35][36]. The development of frailty tools therefore might be further re-purposed to explore their utility in characterizing resilience -thus allowing detection of susceptibility before the onset of frailty, and therefore allowing greater opportunity for successful intervention.Taken together, the studies presented in this special issue underscore the dynamic and evolving nature of frailty assessment tools. From traditional clinical tools such as the CFS to novel machine learning approaches and real-time physiological monitoring, these advances highlight the expanding utility of frailty measures in predicting health outcomes and guiding medical interventions. As frailty remains a significant determinant of vulnerability in aging populations, continued innovation in assessment strategies will be critical for improving patient care, risk stratification, and therapeutic decision-making. Moving forward, integrating multimodal frailty assessment tools-spanning physical performance measures, self-reported scales, and emerging technologies such as wearable sensorsmay offer a more comprehensive approach to capturing frailty's complexity. Yet there are a number of unanswered questions: 1) which assessment framework should be used and when; 2) what types of methods should be considered; 3) how can these methods be integrated into clinical workflow seamlessly; 4) how can the data obtained from these measures be used without further adding burden to already burdened clinicians; and 5) what types of interventions should be considered with specific types of data outputs. This is the tip of the iceberg in terms of integration and translation from science into clinical practice. Ultimately, these advancements hold promise for refining early detection, tailoring interventions, and enhancing quality of life in older adults.