Pathobiology of frailty in lung disease

Physical frailty trajectories in older stroke survivors: Findings from a national cohort study

BACKGROUND

Physical frailty (PF) is highly prevalent and associated with undesirable outcomes in stroke survivors aged 65 years or older. However, the long-term trajectories of PF are understudied in those older stroke survivors.

AIMS

To identify PF trajectories and relative predictors associated with the PF trajectories in older stroke survivors.

DESIGN

This is a secondary analysis of a population-based cohort study in the United States.

METHODS

Six hundred and sixty-three older stroke survivors from the National Health and Ageing Trends Study from 2015 to 2021 were included. PF was operationally assessed based on the Fried Frailty Phenotype. Trajectories were identified by group-based trajectory modelling. The associations between sociodemographic characteristics, clinical factors, symptoms, cognitive factors and PF trajectories were examined using the design-based logistic regression method.

RESULTS

Most older stroke survivors were 75 and older (63.32%), female (53.99%), white (80.54%) and partnered (50.64%). Two PF trajectory groups were identified (Group 1: low risk, robust; 49.47%; Group 2: high risk, deteriorating; 50.53%). Individuals were at a higher risk to be assigned to Group 2 if they were 75-84 years (adjusted odds ratio [aOR]: 2.16, 95% CI: 1.23-3.80) or 85+ years (aOR: 2.77, 95% CI: 1.52-5.04), had fair self-reported health (aOR: 2.78, 95% CI: 1.53-5.07) or poor self-reported health (aOR: 3.37, 95% CI: 1.51-7.52), had comorbidities (aOR: 8.44, 95% CI: 1.31-54.42), had breathing problems (aOR: 2.18, 95% CI: 1.18-4.02) and had balance problems (aOR: 1.70, 95% CI: 1.06-2.73).

CONCLUSION

PF trajectories in older stroke survivors were heterogeneous and were associated with age, self-rated health status, comorbidities, breathing problems and balance problems.

IMPLICATION TO CLINICAL PRACTICE

Early, routine, dynamic screening for stroke-related physical frailty (PF) and relative predictors might be beneficial for identifying the most vulnerable individuals. Our findings might help develop strategies to manage PF progression.

REPORTING METHOD

The reporting followed the STROBE guideline.

Hypoxia-inducible factor and cellular senescence in pulmonary aging and disease

Cellular senescence and hypoxia-inducible factor (HIF) signaling are crucial in pulmonary aging and age-related lung diseases such as chronic obstructive pulmonary disease idiopathic pulmonary fibrosis and lung cancer. HIF plays a pivotal role in cellular adaptation to hypoxia, regulating processes like angiogenesis, metabolism, and inflammation. Meanwhile, cellular senescence leads to irreversible cell cycle arrest, triggering the senescence-associated secretory phenotype which contributes to chronic inflammation, tissue remodeling, and fibrosis. Dysregulation of these pathways accelerates lung aging and disease progression by promoting oxidative stress, mitochondrial dysfunction, and epigenetic alterations. Recent studies indicate that HIF and senescence interact at multiple levels, where HIF can both induce and suppress senescence, depending on cellular conditions. While transient HIF activation supports tissue repair and stress resistance, chronic dysregulation exacerbates pulmonary pathologies. Furthermore, emerging evidence suggests that targeting HIF and senescence pathways could offer new therapeutic strategies to mitigate age-related lung diseases. This review explores the intricate crosstalk between these mechanisms, shedding light on how their interplay influences pulmonary aging and disease progression. Additionally, we discuss potential interventions, including senolytic therapies and HIF modulators, that could enhance lung health and longevity.

The relationship between respiratory symptoms and frailty: findings from observational and Mendelian randomization analyses

INTRODUCTION

As ageing accelerates, frailty increasingly impacts public health. Cough, sputum, wheezing and dyspnea are common respiratory symptoms, and the relationship to frailty is unclear. We aimed to analyze the relationship between respiratory symptoms and frailty.

METHODS

Cross-sectional and Mendelian randomization (MR) studies were used. Cross-sectional data involved 14,021 participants from the National Health and Nutrition Examination Survey (NHANES). Logistic and linear regression were used to analyze the relationship between respiratory symptoms (cough, sputum, wheezing, dyspnea) and frailty. We adjusted for multiple variables and used propensity score matching (PSM). Mediation analysis was used to explore the role of inflammatory markers and age in the relationship between the two. We analyzed the relationship using a two-sample MR approach with data from genome-wide association studies (GWAS) to enhance causal inference.

RESULTS

Observational studies have shown that cough (OR 1.74, 95 CI% 1.44, 2.09), sputum (OR 1.87, 95 CI% 1.57, 2.22), wheezing (OR 2.01, 95 CI% 1.68, 2.40), and dyspnea (OR 2.60, 95 CI% 2.28, 2.97) are associated with an elevated risk of frailty. The PSM results were stable. Mediation analyses indicated that elevated inflammatory markers and advancing age were mediators between respiratory symptoms and frailty. The results of the MR study showed that sputum and wheezing were associated with an elevated frailty index; and in the study of FI on respiratory symptoms, all respiratory symptoms were elevated with elevated FI.

CONCLUSIONS

Our study identified a potential association between frailty and respiratory symptoms. Inflammation and ageing may be essential factors mediating this association.

Association between frailty status and risk of chronic lung disease: an analysis based on two national prospective cohorts

BACKGROUND

The association between the frailty index (FI) and the risk of chronic lung diseases (CLDs) remains unexplored, warranting further research.

METHODS AND MATERIALS

This study investigated the relationship between FI and CLD risk using data from the China Health and Retirement Longitudinal Study (CHARLS) and English Longitudinal Study of Ageing (ELSA), comprising a combined sample of 9642 individuals. Propensity score weighting was used to ensure similar distribution of covariates across FI groups. The Wilcoxon rank-sum test was used to analyze differences in FI scores between groups with and without CLD. Kaplan-Meier curves and Cox regression analysis were employed to explore the association between frailty status and CLD incidence, with sensitivity analyses conducted for validation.

RESULTS

Higher FI scores were significantly associated with increased CLD risk in both cohorts (p < .05). Kaplan-Meier survival and Cox regression analyses indicated that frail individuals have a significantly elevated risk of CLD compared to robust individuals, particularly in certain subgroups (e.g., female) within the CHARLS cohort (p < .05). The ELSA cohort yielded similar results (p < .05), affirming FI as a strong predictor of CLD. Additional risk factors identified included age, smoking, and unmarried status (p < .05). Frail individuals consistently exhibited the highest risk in both cohorts (CHARLS HR = 1.54, p = .003; ELSA HR = 6.64, p < .001). The sensitivity analysis did not substantially alter the significant associations.

CONCLUSION

These findings emphasize the critical role of frailty in the development of CLD, suggesting that targeted interventions could reduce CLD risk.

Lung function and the risk of frailty in the European population: a mendelian randomization study

BACKGROUND

Epidemiological evidence has suggested a relationship between lung function and frailty, but the precise nature of the causality remains unclear. In this study, we applied a two-sample Mendelian randomization (MR) analysis to determine the causal effects of lung function on frailty.

METHODS

Single nucleotide polymorphisms (SNPs) independently related (P ≤ 5E-08) to lung function, as identified by genome-wide association study (GWAS), were applied as instrumental variables (IV). The association with frailty index (FI) was investigated using summary-level data from the latest GWAS on FI (n = 175,226). Different statistical methods were employed to evaluate the causal estimates between lung function and FI. The pleiotropy, heterogeneity, and leave-one-out analysis were applied to confirm the stability of the MR estimates.

RESULTS

Using the random-effect inverse-variance weighted approach, genetically proxied forced expiratory volume in the first second (FEV1), ratio of FEV1 on forced vital capacity (FVC) [FEV1/FVC], and peak expiratory flow (PEF) were significantly and inversely associated with FI (FEV1, β = -0.08, P = 2.03E-05; FEV1/FVC, β = -0.06, P = 9.51E-06; PEF, β = -0.07, P = 4.09E-04) with good statistical power (99.7-100%). However, no significant association was observed between FVC and FI (β = -0.01, P = 0.681). Leave-one-out analysis showed that there was no single SNP driving the bias of the estimates. There was potential heterogeneity, but no obvious pleiotropy was founded in this MR study.

CONCLUSIONS

Our findings indicate that impaired pulmonary function is closely related to the risk of frailty. Enhancing lung function in the elderly population may contribute to the prevention of frailty to a certain extent.

Development and validation of a preliminary clinical support system for measuring the probability of incident 2-year (pre)frailty among community-dwelling older adults: A prospective cohort study

OBJECTIVE

To develop the wed-based system for predicting risk of (pre)frailty among community-dwelling older adults.

MATERIALS AND METHODS

(Pre)frailty was determined by physical frailty phenotype scale. A total of 2802 robust older adults aged ≥60 years from the China Health and Retirement Longitudinal Study (CHARLS) 2013-2015 survey were randomly assigned to derivation or internal validation cohort at a ratio of 8:2. Logistic regression, Random Forest, Support Vector Machine and eXtreme Gradient Boosting (XGBoost) were used to construct (pre)frailty prediction models. The Grid search and 5-fold cross validation were combined to find the optimal parameters. All models were evaluated externally using the temporal validation method via the CHARLS 2011-2013 survey. The (pre)frailty predictive system was web-based and built upon representational state transfer application program interfaces.

RESULTS

The incidence of (pre)frailty was 34.2 % in derivation cohort, 34.8 % in internal validation cohort, and 32.4 % in external validation cohort. The XGBoost model achieved better prediction performance in derivation and internal validation cohorts, and all models had similar performance in external validation cohort. For internal validation cohort, XGBoost model showed acceptable discrimination (AUC: 0.701, 95 % CI: [0.655-0.746]), calibration (p-value of Hosmer-Lemeshow test > 0.05; good agreement on calibration plot), overall performance (Brier score: 0.200), and clinical usefulness (decision curve analysis: more net benefit than default strategies within the threshold of 0.15-0.80). The top 3 of 14 important predictors generally available in community were age, waist circumference and cognitive function. We embedded XGBoost model into the server and this (pre)frailty predictive system is accessible at http://www.frailtyprediction.com.cn. A nomogram was also conducted to enhance the practical use.

CONCLUSIONS

A user-friendly web-based system was developed with good performance to assist healthcare providers to measure the probability of being (pre)frail among community-dwelling older adults in the next two years, facilitating the early identification of high-risk population of (pre)frailty. Further research is needed to validate this preliminary system across more controlled cohorts.

Prevalence and risk factors of frailty in patients with chronic obstructive pulmonary disease: systematic review and meta-analysis

OBJECTIVE

To systematically review the prevalence and risk factors for frailty in patients with chronic obstructive pulmonary disease (COPD).

METHODS

A systematic review and meta-analysis were conducted, and a search of the PubMed, Embase and Web of Science databases was carried out to collect Chinese and English studies on frailty and COPD published up to September 5, 2022.

RESULTS

A total of 38 articles were included for the quantitative analysis after the collected literature was either included or omitted based on pertinent criteria. The results indicated that the estimated overall pooled prevalence of frailty was 36% (95% confidence interval [CI] = 31-41%), and the estimated pre-frailty was 43% (95% CI = 37-49%). A higher age (odds ratio [OR] = 1.04; 95% CI = 1.01-1.06) and higher COPD assessment test (CAT) score (OR = 1.19; 95% CI = 1.12-1.27) were associated with a significantly increased likelihood of frailty in patients with COPD. However, a higher educational attainment (OR = 0.55; 95% CI = 0.43-0.69) and higher income (OR = 0.63; 95% CI = 0.45-0.88) were associated with a significantly reduced risk of frailty in patients with COPD. A total of 17 other risk factors for frailty were identified via qualitative synthesis.

CONCLUSION

The incidence of frailty in patients with COPD is high, and there are many influencing factors.

European Respiratory Society statement on frailty in adults with chronic lung disease

Frailty is a complex, multidimensional syndrome characterised by a loss of physiological reserves that increases a person's susceptibility to adverse health outcomes. Most knowledge regarding frailty originates from geriatric medicine; however, awareness of its importance as a treatable trait for people with chronic respiratory disease (including asthma, COPD and interstitial lung disease) is emerging. A clearer understanding of frailty and its impact in chronic respiratory disease is a prerequisite to optimise clinical management in the future. This unmet need underpins the rationale for undertaking the present work. This European Respiratory Society statement synthesises current evidence and clinical insights from international experts and people affected by chronic respiratory conditions regarding frailty in adults with chronic respiratory disease. The scope includes coverage of frailty within international respiratory guidelines, prevalence and risk factors, review of clinical management options (including comprehensive geriatric care, rehabilitation, nutrition, pharmacological and psychological therapies) and identification of evidence gaps to inform future priority areas of research. Frailty is underrepresented in international respiratory guidelines, despite being common and related to increased hospitalisation and mortality. Validated screening instruments can detect frailty to prompt comprehensive assessment and personalised clinical management. Clinical trials targeting people with chronic respiratory disease and frailty are needed.

Subphenotypes of frailty in lung transplant candidates

Heterogeneous frailty pathobiology might explain the inconsistent associations observed between frailty and lung transplant outcomes. A Subphenotype analysis could refine frailty measurement. In a 3-center pilot cohort study, we measured frailty by the Short Physical Performance Battery, body composition, and serum biomarkers reflecting causes of frailty. We applied latent class modeling for these baseline data. Next, we tested class construct validity with disability, waitlist delisting/death, and early postoperative complications. Among 422 lung transplant candidates, 2 class model fit the best (P = .01). Compared with Subphenotype 1 (n = 333), Subphenotype 2 (n = 89) was characterized by systemic and innate inflammation (higher IL-6, CRP, PTX3, TNF-R1, and IL-1RA); mitochondrial stress (higher GDF-15 and FGF-21); sarcopenia; malnutrition; and lower hemoglobin and walk distance. Subphenotype 2 had a worse disability and higher risk of waitlist delisting or death (hazards ratio: 4.0; 95% confidence interval: 1.8-9.1). Of the total cohort, 257 underwent transplant (Subphenotype 1: 196; Subphenotype 2: 61). Subphenotype 2 had a higher need for take back to the operating room (48% vs 28%; P = .005) and longer posttransplant hospital length of stay (21 days [interquartile range: 14-33] vs 18 days [14-28]; P = .04). Subphenotype 2 trended toward fewer ventilator-free days, needing more postoperative extracorporeal membrane oxygenation and dialysis, and higher need for discharge to rehabilitation facilities (P ≤ .20). In this early phase study, we identified biological frailty Subphenotypes in lung transplant candidates. A hyperinflammatory, sarcopenic Subphenotype seems to be associated with worse clinical outcomes.

Longitudinal association of lung function with frailty among older adults: the English Longitudinal Study of Ageing

PURPOSE

To investigate the effect of baseline lung function on the trajectory of frailty over time.

METHODS

This longitudinal study included 3,658 adults aged 60 and over (average age 70.4 years old and 46.4% males) at baseline from the English Longitudinal Study of Ageing. Lung function indicators included forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1), both measured at baseline examination. Frailty was defined based on Fried's frailty phenotype criteria, the measurement was repeated for four times. Linear mixed-effect regression model was applied to estimate the association of baseline lung function with the trajectory of frailty over time.

RESULTS

Frailty score increased significantly over time (β = 0.030, P < 0.001). Linear mixed-effect regression model identified significant interactions between FVC (β =- 0.018, P < 0.001) or FEV1 (β =- 0.022, P < 0.001) and time on frailty.

CONCLUSION

Poor baseline lung function might accelerate the speed of frailty. Lung function might be an important predictor of the development and progression of frailty among older adults.

Prehabilitation in Adult Solid Organ Transplant Candidates

Purpose of Review

To highlight the importance of biological age in the context of prehabilitation and to present relevant research regarding prehabilitation prior to solid organ transplantation.

Recent Findings

Studies on the effect of prehabilitation have been performed in kidney-, lung-, liver-, and heart transplant patient populations. Prior to kidney transplantation, exercise interventions have been shown to improve cardiopulmonary- and physical fitness and result in a decreased length of hospital stay postoperatively. Among lung transplant candidates, various methods of prehabilitation have been studied including home-based, outpatient and in-patient programs, consisting of physical training, psychological support, education, and nutritional interventions. Overall, prehabilitation seems to improve or maintain quality of life and exercise capacity in this patient population. Patients undergoing liver transplantation seem to benefit from prehabilitation as well. Not only does it seem safe and feasible, but significant improvements in aerobic and functional capacity have also been found. Regarding heart transplant candidates, both inpatient and outpatient, supervised prehabilitation programs show promising results with improvements in exercise capacities and quality of life.

Summary

Prehabilitation is an effective and safe intervention for improving functional outcomes of solid organ transplant patients. Future studies should evaluate whether prehabilitation translates into improved pre- and post-transplant clinical outcomes.

The Intersection of Aging and Lung Transplantation: its Impact on Transplant Evaluation, Outcomes, and Clinical Care

Purpose

Older adults (age ≥ 65 years) are the fastest growing age group undergoing lung transplantation. Further, international consensus document for the selection of lung transplant candidates no longer suggest a fixed upper age limit. Although carefully selected older adults can derive great benefit, understanding which older adults will do well after transplant with improved survival and health-related qualiy of life is key to informed decision-making. Herein, we review the epidemiology of aging in lung transplantation and its impact on outcomes, highlight selected physiological measures that may be informative when evaluating and managing older lung transplant patients, and identify directions for future research.

Recent Findings

In general, listing and transplanting older, sicker patients has contributed to worse clinical outcomes and greater healthcare use. Emerging evidence suggest that measures of physiological age, such as frailty, body composition, and neurocognitive and psychosocial function, may better identify risk for poor transplant outcomes than chronlogical age.

Summary

The evidence base to inform transplant decision-making and improvements in care for older adults is small but growing. Multipronged efforts at the intersection of aging and lung transplantation are needed to improve the clinical and patient centered outcomes for this large and growing cohort of patients. Future research should focus on identifying novel and ideally modifiable risk factors for poor outcomes specific to older adults, better approaches to measuring physiological aging (e.g., frailty, body composition, neurocognitive and psychosocial function), and the underlying mechanisms of physiological aging. Finally, interventions that can improve clinical and patient centered outcomes for older adults are needed.

Screening for frailty and sarcopenia in community-dwelling older adults: a cross-sectional study from the Eastern Black Sea region of Turkey

AIM

The purpose of this study was to investigate the prevalence of frailty, sarcopenia and associated factors among community-dwelling older adults living in the Eastern Black Sea region of Turkey.

METHODS

The study sample comprised 404 community-dwelling older adults living in the Eastern Black Sea region of Turkey. These subjects or proxies were contacted by mobile phone or the internet. The sociodemographic characteristics, falls and chronic pain were recorded. Frailty, sarcopenia, malnutrition, activities of daily living and instrumental activities of daily living were assessed using the FRAIL scale, SARC-F, Mini Nutrition Assessment-Short Form, Barthel Index and Lawton instrumental activities of daily living scale, respectively.

RESULTS

The 404 older adults comprised 62% females and 38% males with a mean age of 73.4 ± 7.4 years. The prevalence of positive frailty and sarcopenia screening were detected as 37.4% and 46.8%, respectively. The strongest associations with frailty were the presence of chronic lung disease [Odds ratio (OR) = 10.3; 95% confidence interval (CI) = 2.1, 49.8] and chronic pain [OR = 6.9; 95% CI = 3.2, 15.0]. The associations with sarcopenia were falls (OR = 7.4; 95% CI = 4.2, 12.9), dependence in instrumental activities of daily living (OR = 4.3; 95% CI = 2.2, 8.4), advancing age (OR = 2.6; 95% Cl = 1.4, 4.7), and dependence in daily living activities (OR = 2.2; 95% Cl = 1.3, 4.0). Female gender and falls were found to be co-related factors for frailty and sarcopenia.

CONCLUSIONS

Female gender and falls were independently associated with frailty and sarcopenia. In addition, chronic lung disease and chronic pain were major risk factors for frailty, while advancing age and dependence in daily living activities were major risk factors for sarcopenia. These factors should be considered to be able to identify individuals at high risk of frailty and sarcopenia and to prevent these geriatric syndromes.

Frailty is an independent risk factor for postoperative pulmonary complications in elderly patients undergoing video-assisted thoracoscopic pulmonary resections

BACKGROUND

Although frailty as a common geriatric syndrome is associated with postoperative complications, its relationship with postoperative pulmonary complications (PPCs) following pulmonary resections in elderly patients is unclear.

AIMS

To investigate the relationship between frailty and PPCs in elderly patients undergoing video-assisted thoracoscopic pulmonary resections and explore the effect of the addition of frailty assessment to PPC risk index and ASA on their predictive ability.

METHODS

In a prospective cohort study, we measured frailty status using the FRAIL scale in elderly patients undergoing video-assisted thoracoscopic pulmonary resections. Multivariate analysis was used to identify the relationship between frailty and PPCs. Receiver operating characteristic curves were used to examine the predictive power of frailty and other assessment tools.

RESULTS

227 patients were analyzed in the study. The prevalence of PPCs was 24.7%. Significant differences between patients with and without PPCs were observed in the following aspects: BMI, smoking, COPD, respiratory infection within the last month, FEV1/FVC ratio, creatinine, ASA, frailty and PPC risk index (p < 0.05, respectively). After adjusting for all covariates, frailty was significantly related to PPCs in elderly patients (odds ratio: 6.33, 95% confidence interval: 2.45-16.37). Combined with frailty assessment, the area under the curve for ASA class and PPC risk index was increased to 0.759 (95% CI 0.687-0.831) and 0.821 (95% CI 0.758-0.883).

CONCLUSIONS

Frailty was associated with PPCs in elderly patients undergoing video-assisted thoracoscopic pulmonary resections. Combined with the frailty assessment, the predictive power of the PPC risk index and ASA class was improved.

Frailty in Lung Transplantation: Candidate Assessment and Optimization

The concept of frailty has gained considerable interest in clinical solid-organ transplantation over the past decade. Frailty as a phenotypic construct to describe a patient's risk from biologic stresses has an impact on posttransplant survival. There is keen interest in characterizing frailty in lung transplantation, both to determine which patients are suitable candidates for listing and also to prepare for their care in the aftermath of lung transplantation. Here, we review the current status of research on frailty in lung transplant candidates and recipients. This review will highlight areas of uncertainty for frailty in clinical lung transplantation that are likely to impact the state-of-the-art in the field for the next decade.

Activation of p21 limits acute lung injury and induces early senescence after acid aspiration and mechanical ventilation

The p53/p21 pathway is activated in response to cell stress. However, its role in acute lung injury has not been elucidated. Acute lung injury is associated with disruption of the alveolo-capillary barrier leading to acute respiratory distress syndrome (ARDS). Mechanical ventilation may be necessary to support gas exchange in patients with ARDS, however, high positive airway pressures can cause regional overdistension of alveolar units and aggravate lung injury. Here, we report that acute lung injury and alveolar overstretching activate the p53/p21 pathway to maintain homeostasis and avoid massive cell apoptosis. A systematic pooling of transcriptomic data from animal models of lung injury demonstrates the enrichment of specific p53- and p21-dependent gene signatures and a validated senescence profile. In a clinically relevant, murine model of acid aspiration and mechanical ventilation, we observed changes in the nuclear envelope and the underlying chromatin, DNA damage and activation of the Tp53/p21 pathway. Absence of Cdkn1a decreased the senescent response, but worsened lung injury due to increased cell apoptosis. Conversely, treatment with lopinavir and/or ritonavir led to Cdkn1a overexpression and ameliorated cell apoptosis and lung injury. The activation of these mechanisms was associated with early markers of senescence, including expression of senescence-related genes and increases in senescence-associated heterochromatin foci in alveolar cells. Autopsy samples from lungs of patients with ARDS revealed increased senescence-associated heterochromatin foci. Collectively, these results suggest that acute lung injury activates p53/p21 as an antiapoptotic mechanism to ameliorate damage, but with the side effect of induction of senescence.