Construct and Predictive Validity of Sarcopenia in Lung Transplant Candidates

A leaky gut contributes to reduced sarcopenia-related quality of life (SarQoL) in geriatric older adults

PURPOSE

The sarcopenia quality-of-life (SarQoL) questionnaire is designed to evaluate the quality of life of sarcopenic patients. A pathological increase in intestinal permeability leads to several systemic diseases, but its contribution to SarQoL is unknown.

METHODS

We recruited controls (n = 84, age = 74.6 ± 4.9 years) and sarcopenic (n = 55, age = 76.1 ± 4.2 years) men for validating and adapting a Pashto version of SarQoL. We measured the scores for seven domains of SarQoL, body composition, and handgrip strength (HGS). We also measured plasma zonulin as a marker of increased intestinal permeability.

RESULTS

The Pashto SarQoL exhibited adequate discriminative ability, construct validity, internal consistency, and test-retest reliability, without exhibiting the floor and ceiling effect. Sarcopenic patients had higher plasma zonulin and lower scores on SarQoL domains for physical and mental health, locomotion, body composition, functionality, activities of daily living, leisure, and fear, and cumulative SarQoL scores than controls. Plasma zonulin exhibited significant coefficients of determination with Pashto SarQoL domains for locomotion (r2 = 0.217), functionality (r2 = 0.101), activities of daily living (r2 = 0.302), and cumulative SarQoL scores (r2 = 0.168). We also found high efficacies of zonulin in diagnosing low scores for functionality (AUC = 0.785, 95% C.I = 0.708-0.863), activities of daily living (AUC = 0.785, 95% C.I = 0.708-0.863), and cumulative SarQoL scores (AUC = 0.821, 95% C.I = 0.751-0.891).

CONCLUSION

Altogether, SarQoL appears reliable in measuring the quality of life in sarcopenic patients. A leaky gut has a potential contribution to reduced SarQoL in sarcopenia.

The Association Between Frailty and Chronic Lung Allograft Dysfunction After Lung Transplantation

BACKGROUND

After lung transplantation, both frailty and chronic lung allograft dysfunction (CLAD) commonly develop, and when they do, are associated with poorer outcomes. Given their potential shared mechanisms, we sought to explore the temporal relationship between frailty and CLAD onset.

METHODS

In a single center, we prospectively measured frailty by the short physical performance battery (SPPB) repeatedly after transplant. Because of the nature of the relationship between frailty and CLAD is unknown, we tested the association between frailty, modeled as a time-dependent predictor, and CLAD development as well as CLAD development, modeled as a time-dependent predictor, and frailty development. To do so, we used Cox proportional cause-specific hazards and conditional logistic regression models adjusted for age, sex, race, diagnosis, cytomegalovirus serostatus, posttransplant body mass index, and acute cellular rejection episodes as time-dependent covariates. We tested SPPB frailty as a binary (≤9 points) and continuous predictor (12-point scale); as an outcome, we defined frailty as SPPB ≤9.

RESULTS

The 231 participants were a mean age of 55.7 y (SD 12.1). After adjusting for covariates, the development of frailty within 3 y after lung transplant was associated with cause-specific CLAD risk (adjusted cause-specific hazard ratio: 1.76; 95% confidence interval [CI], 1.05-2.92 when defining frailty as SPPB ≤9 and adjusted cause-specific hazard ratio: 1.10, 95% CI, 1.03-1.18 per 1-point worsening in SPPB). CLAD onset did not appear to be a risk factor for subsequent frailty (odds ratio, 4.0; 95% CI, 0.4-197.0).

CONCLUSIONS

Studying the mechanisms underlying frailty and CLAD could provide new insights into the pathobiology of both and potential targets for intervention.

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.

Handgrip Strength in Lung Transplant Candidates and Recipients

OBJECTIVES

Handgrip strength is increasingly used to assess muscle strength in various conditions. In this review, we investigated handgrip strength in patients receiving or awaiting lung transplant.

MATERIALS AND METHODS

For this integrative review, we searched 8 databases from inception through February 2023. Two keyword entries, "handgrip strength" and "lung transplantation," were matched using the Boolean operator, AND. No filters were applied for document type, age, sex, publication date, language, and subject.

RESULTS AND CONCLUSIONS

The searched databases returned 73 citations. Nine articles considering 487 patients (49% female) were included in the final analysis; 7 studies were observational, and 2 were randomized controlled trials. In 7 of 9 studies, handgrip strength was measured with a hydraulic dynamometer. In candidates for lung transplant, handgrip strength ranged from 27.1 kg (before rehabilitation) to 31.2 kg (after rehabilitation). In lung transplant recipients, handgrip strength ranged from 21.1 kg (before rehabilitation) to 35.7 kg (after rehabilitation). Handgrip strength in lung transplant candidates with chronic obstructive pulmonary disease was higher (89 ± 18% predicted) versus patients with interstitial lung disease (79 ± 18% predicted). Improvements in maximal inspiratory pressure and maximal expiratory pressure were observed in those patients whose handgrip strength improved after rehabilitation. Nonsarcopenic patients walked longer distances for the 6-minute walking test (>450 m) versus sarcopenic patients (<310 m) and had higher handgrip strength (>20 kg) versus sarcopenic patients (<20 kg). Handgrip strength testing should be implemented both in preoperative and postoperative contexts to evaluate physical potential of patients and drive rehabilitative activities toward the most impaired domains.

Development of the Lung Transplant Frailty Scale (LT-FS)

BACKGROUND

Existing measures of frailty developed in community dwelling older adults may misclassify frailty in lung transplant candidates. We aimed to develop a novel frailty scale for lung transplantation with improved performance characteristics.

METHODS

We measured the short physical performance battery (SPPB), fried frailty phenotype (FFP), Body Composition, and serum Biomarkers representative of putative frailty mechanisms. We applied a 4-step established approach (identify frailty domain variable bivariate associations with the outcome of waitlist delisting or death; build models sequentially incorporating variables from each frailty domain cluster; retain variables that improved model performance ability by c-statistic or AIC) to develop 3 candidate "Lung Transplant Frailty Scale (LT-FS)" measures: 1 incorporating readily available clinical data; 1 adding muscle mass, and 1 adding muscle mass and research-grade Biomarkers. We compared construct and predictive validity of LT-FS models to the SPPB and FFP by ANOVA, ANCOVA, and Cox proportional-hazard modeling.

RESULTS

In 342 lung transplant candidates, LT-FS models exhibited superior construct and predictive validity compared to the SPPB and FFP. The addition of muscle mass and Biomarkers improved model performance. Frailty by all measures was associated with waitlist disability, poorer HRQL, and waitlist delisting/death. LT-FS models exhibited stronger associations with waitlist delisting/death than SPPB or FFP (C-statistic range: 0.73-0.78 vs. 0.57 and 0.55 for SPPB and FFP, respectively). Compared to SPPB and FFP, LT-FS models were generally more strongly associated with delisting/death and improved delisting/death net reclassification, with greater improvements with increasing LT-FS model complexity (range: 0.11-0.34). For example, LT-FS-Body Composition hazard ratio for delisting/death: 6.0 (95%CI: 2.5, 14.2), SPPB HR: 2.5 (95%CI: 1.1, 5.8), FFP HR: 4.3 (95%CI: 1.8, 10.1). Pre-transplant LT-FS frailty, but not SPPB or FFP, was associated with mortality after transplant.

CONCLUSIONS

The LT-FS is a disease-specific physical frailty measure with face and construct validity that has superior predictive validity over established measures.

Body Mass Index and Cause-Specific Mortality after Lung Transplantation in the United States

Rationale: Low and high body mass index (BMI) are associated with increased mortality after lung transplantation. Why extremes of BMI might increase risk of death is unknown. Objectives: To estimate the association of extremes of BMI with causes of death after transplantation. Methods: We performed a retrospective study of the United Network for Organ Sharing database, including 26,721 adults who underwent lung transplantation in the United States between May 4, 2005, and December 2, 2020. We mapped 76 reported causes of death into 16 distinct groups. We estimated cause-specific hazards for death from each cause using Cox models. Results: Relative to a subject with a BMI of 24 kg/m2, a subject with a BMI of 16 kg/m2 had 38% (hazard ratio [HR], 1.38; 95% confidence interval [95% CI], 0.99-1.90), 82% (HR, 1.82; 95% CI, 1.34-2.46), and 62% (HR, 1.62; 95% CI, 1.18-2.22) increased hazards of death from acute respiratory failure, chronic lung allograft dysfunction (CLAD), and infection, respectively, and a subject with a BMI of 36 kg/m2 had 44% (HR, 1.44; 95% CI, 0.97-2.12), 42% (HR, 1.42; 95% CI, 0.93-2.15), and 185% (HR, 2.85; 95% CI, 1.28-6.33) increased hazards of death from acute respiratory failure, CLAD, and primary graft dysfunction, respectively. Conclusions: Low BMI is associated with increased risk of death from infection, acute respiratory failure, and CLAD after lung transplantation, whereas high BMI is associated with increased risk of death from primary graft dysfunction, acute respiratory failure, and CLAD.

Association between Body Composition and the Risk of Portopulmonary Hypertension Assessed by Computed Tomography in Patients with Liver Cirrhosis

The aim of this study is to investigate the impact of body composition on the risk of portopulmonary hypertension using computed tomography (CT) in patients with liver cirrhosis. We retrospectively included 148 patients with cirrhosis treated at our hospital between March 2012 and December 2020. POPH high-risk was defined as main pulmonary artery diameter (mPA-D) ≥ 29 mm or mPA-D to ascending aorta diameter ratio ≥ 1.0, based on chest CT. Body composition was assessed using CT images of the third lumbar vertebra. The factors associated with POPH high-risk were evaluated using logistic regression and decision tree analyses, respectively. Among the 148 patients, 50% were females, and 31% were found to be high-risk cases on evaluation of chest CT images. Patients with a body mass index (BMI) of ≥25 mg/m² had a significantly higher prevalence of POPH high-risk than those with a BMI < 25 mg/m² (47% vs. 25%, p = 0.019). After adjusting for confounding factors, BMI (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.10-1.33), subcutaneous adipose tissue index (OR, 1.02; 95% CI, 1.01-1.03), and visceral adipose tissue index (OR, 1.03; 95% CI, 1.01-1.04) were associated with POPH high-risk, respectively. In the decision tree analysis, the strongest classifier of POPH high-risk was BMI, followed by the skeletal muscle index. Body composition may affect the risk of POPH based on chest CT assessment in patients with cirrhosis. Since the present study lacked data on right heart catheterization, further studies are required to confirm the results of our study.

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.

Lung transplantation outcomes in underweight recipients: A single center experience

Background

Current guidelines recommend a body mass index (BMI) of 16 kg/m² as the minimum threshold for lung transplantation, despite mixed evidence on outcomes in underweight patients. The current study aimed to describe survival outcomes of underweight patients who underwent lung transplantation at a single center.

Methods

This retrospective observational study included adult lung transplant recipients who underwent transplantation for the first time between March 2010 and March 2022 at King Faisal Specialist Hospital and Research Center and excluded patients with obesity. We defined an underweight status as a BMI <17 kg/m².

Results

Forty-eight of the 202 lung transplant recipients were underweight at the time of surgery. The underweight patients had similar lengths of hospital (p = 0.53) and intensive care unit (p = 0.81) stays compared to other patients. Thirty-three percent of underweight patients had died within 5-year follow-up, compared to 34% of patients who were not underweight. There was no significant difference in mortality risk between underweight patients and patients with normal BMIs in our multivariable Cox regression model (adjusted HR 1.57, 95%CI: 0.77-3.20, p = 0.21). Exploratory analyses revealed that a pre-transplant BMI <13 kg/m² was associated with a trend towards increased 5-year mortality (adjusted HR 4.00, 95%CI: 0.87-18.35, p = 0.07).

Conclusions

Our findings suggest that patients with BMIs of 13-17 kg/m² may be candidates for lung transplantation. Large multi-center cohort studies are needed to confirm the lower BMI limit for safely transplanting patients.

Computed tomography body composition and clinical outcomes following lung transplantation in cystic fibrosis

BACKGROUND

Low muscle mass is common in patients approaching lung transplantation and may be linked to worse post-transplant outcomes. Existing studies assessing muscle mass and post-transplant outcomes include few patients with cystic fibrosis (CF).

METHODS

Between May 1993 and December 2018, 152 adults with CF received lung transplants at our institution. Of these, 83 met inclusion criteria and had usable computed tomography (CT) scans. Using Cox proportional hazards regression, we evaluated the association between pre-transplant thoracic skeletal muscle index (SMI) and our primary outcome of death after lung transplantation. Secondary outcomes, including days to post-transplant extubation and post-transplant hospital and intensive care unit (ICU) length of stay, were assessed using linear regression. We also examined associations between thoracic SMI and pre-transplant pulmonary function and 6-min walk distance.

RESULTS

Median thoracic SMI was 26.95 cm²/m² (IQR 23.97, 31.32) for men and 22.83 cm²/m² (IQR 21.27, 26.92) for women. There was no association between pre-transplant thoracic SMI and death after transplant (HR 1.03; 95% CI 0.95, 1.11), days to post-transplant extubation, or post-transplant hospital or ICU length of stay. There was an association between pre-transplant thoracic SMI and pre-transplant FEV1% predicted (b = 0.39; 95% CI 0.14, 0.63), with higher SMI associated with higher FEV1% predicted.

CONCLUSIONS

Skeletal muscle index was low for men and women. We did not identify a significant relationship between pre-transplant thoracic SMI and post-transplant outcomes. There was an association between thoracic SMI and pre-transplant pulmonary function, confirming the potential value of sarcopenia as a marker of disease severity.

Listing Dilemmas: Age, Frailty, Weight, Preexisting Cancers, and Systemic Diseases

Selection of lung transplant candidates is an evolving field that pushes the boundaries of what is considered the norm. Given the continually changing demographics of the typical lung transplant recipient as well as the growing list of risk factors that predispose patients to poor posttransplant outcomes, we explore the dilemmas in lung transplant candidate selections pertaining to older age, frailty, low and high body mass index, preexisting cancers, and systemic autoimmune rheumatic diseases.

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.

Taskforce report on the diagnosis and clinical management of COVID-19 associated pulmonary aspergillosis

Purpose

Invasive pulmonary aspergillosis (IPA) is increasingly reported in patients with severe coronavirus disease 2019 (COVID-19) admitted to the intensive care unit (ICU). Diagnosis and management of COVID-19 associated pulmonary aspergillosis (CAPA) are challenging and our aim was to develop practical guidance.

Methods

A group of 28 international experts reviewed current insights in the epidemiology, diagnosis and management of CAPA and developed recommendations using GRADE methodology.

Results

The prevalence of CAPA varied between 0 and 33%, which may be partly due to variable case definitions, but likely represents true variation. Bronchoscopy and bronchoalveolar lavage (BAL) remain the cornerstone of CAPA diagnosis, allowing for diagnosis of invasive Aspergillus tracheobronchitis and collection of the best validated specimen for Aspergillus diagnostics. Most patients diagnosed with CAPA lack traditional host factors, but pre-existing structural lung disease and immunomodulating therapy may predispose to CAPA risk. Computed tomography seems to be of limited value to rule CAPA in or out, and serum biomarkers are negative in 85% of patients. As the mortality of CAPA is around 50%, antifungal therapy is recommended for BAL positive patients, but the decision to treat depends on the patients’ clinical condition and the institutional incidence of CAPA. We recommend against routinely stopping concomitant corticosteroid or IL-6 blocking therapy in CAPA patients.

Conclusion

CAPA is a complex disease involving a continuum of respiratory colonization, tissue invasion and angioinvasive disease. Knowledge gaps including true epidemiology, optimal diagnostic work-up, management strategies and role of host-directed therapy require further study.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-021-06449-4.