Impact of the lung allocation score on survival beyond 1 year

Disturbed sleep after lung transplantation is associated with worse patient-reported outcomes and chronic lung allograft dysfunction

Many lung transplant recipients fail to derive the expected improvements in functioning, HRQL, or long-term survival. Sleep may represent an important, albeit rarely examined, factor influencing lung transplant outcomes. Within a larger cohort study, 141 lung transplant recipients completed the Medical Outcomes Study (MOS) Sleep Scale along with a broader survey of patient-reported outcome (PRO) measures and frailty assessment. MOS Sleep yields the Sleep Problems Index (SPI); we also derived an insomnia-specific subscale. Potential perioperative predictors of disturbed sleep and time to chronic lung allograft dysfunction (CLAD) and death were derived from medical records. We investigated associations between perioperative predictors on SPI and Insomnia and associations between SPI and Insomnia on PROs and frailty by linear regressions, adjusting for age, sex, and lung function. We evaluated the associations between SPI and Insomnia on time to CLAD and death using Cox models, adjusting for age, sex, and transplant indication. Post-transplant hospital length of stay >30 days was associated with worse sleep by SPI and insomnia (SPI: p=0.01; Insomnia p=0.02). Worse sleep by SPI and insomnia was associated with worse depression, cognitive function, HRQL, physical disability, health utilities, and Fried Frailty Phenotype frailty (all p<0.01). Those in the worst quartile of SPI and insomnia exhibited increased risk of CLAD (HR 2.18; 95%CI: 1.22-3.89 ; p=0.01 for SPI and HR 1.96; 95%CI 1.09-3.53; p=0.03 for insomnia). Worsening in SPI but not insomnia was also associated with mortality (HR: 1.29; 95%CI: 1.05-1.58; p=0.01). Poor sleep after lung transplant may be a novel predictor of patient reported outcomes, frailty, CLAD, and death with potentially important screening and treatment implications.

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.

A Conceptual Model for Sources of Differential Selection in Lung Transplant Allocation

Rationale: In the United States, donor lungs are allocated to transplant candidates on the basis of lung allocation scores (LAS). However, additional factors beyond the LAS can impact who is transplanted, including listing and donor-organ acceptance practices. These factors can result in differential selection, undermining the objectivity of lung allocation. Yet their impact on the lung transplant pathway has been underexplored. Objectives: We sought to systematically examine sources of differential selection in lung transplantation via qualitative methods. Methods: We conducted semistructured qualitative interviews with lung transplant surgeons and pulmonologists in the United States between June 2019 and June 2020 to understand clinician perspectives on differential selection in lung transplantation and the LAS. Results: A total of 51 respondents (30 surgeons and 21 pulmonologists) identified many sources of differential selection arising throughout the pathway from referral to transplantation. We synthesized these sources into a conceptual model with five themes: 1) transplant center's degree of risk tolerance and accountability; 2) successfulness and fairness of the LAS; 3) donor-organ availability and regional competition; 4) patient health versus program health; and 5) access to care versus responsible stewardship of organs. Conclusions: Our conceptual model demonstrates how differential selection can arise throughout lung transplantation and facilitates the further study of such selection. As new organ allocation models are developed, differential selection should be considered carefully to ensure that these models are more equitable.

Clinical impact of a modified lung allocation score that mitigates selection bias

BACKGROUND

The Lung Allocation Score (LAS) is used in the U.S. to prioritize lung transplant candidates. Selection bias, induced by dependent censoring of waitlisted candidates and prediction of posttransplant survival among surviving, transplanted patients only, is only partially addressed by the LAS. Recently, a modified LAS (mLAS) was designed to mitigate such bias. Here, we estimate the clinical impact of replacing the LAS with the mLAS.

METHODS

We considered lung transplant candidates waitlisted during 2016 and 2017. LAS and mLAS scores were computed for each registrant at each observed organ offer date; individuals were ranked accordingly. Patient characteristics associated with better priority under the mLAS were investigated via logistic regression and generalized linear mixed models. We also determined whether differences in rank were explained more by changes in predicted pre- or posttransplant survival. Simulations examined how 1-year waitlist, posttransplant, and overall survival might change under the mLAS.

RESULTS

Diagnosis group, 6-minute walk distance, continuous mechanical ventilation, functional status, and age demonstrated the highest impact on differential allocation. Differences in rank were explained more by changes in predicted pretransplant survival than changes in predicted posttransplant survival, suggesting that selection bias has more impact on estimates of waitlist urgency. Simulations suggest that for every 1000 waitlisted individuals, 12.8 (interquartile range: 5.2-24.3) fewer waitlist deaths per year would occur under the mLAS, without compromising posttransplant and overall survival.

CONCLUSIONS

Implementing a mLAS that mitigates selection bias into clinical practice can lead to important differences in allocation and possibly modest improvement in waitlist survival.

Recipient Management before Lung Transplantation

Lung transplantation is considered a viable treatment option for patients with end-stage lung disease. Recent decades have seen a gradual increase in the number of lung transplantation patients worldwide, and in South Korea, the case number has increased at least 3-fold during the last decade. Furthermore, the waiting list time is becoming longer, and more elderly patients (>65 years) are undergoing lung transplantation; that is, the patients placed on the waiting list are older and sicker than in the past. Hence, proper management during the pre-transplantation period, as well as careful selection of candidates, is a key factor for transplant success and patient survival. Although referring and transplant centers should address many issues, the main areas of focus should be the timing of referral, nutrition, pulmonary rehabilitation, critical care (including mechanical ventilation and extracorporeal membrane oxygenation), psychological support, and the management of preexisting comorbid conditions (coronary artery disease, diabetes mellitus, gastroesophageal reflux disease, osteoporosis, malignancy, viral infections, and chronic infections). In this context, the present article reviews and summarizes the pre-transplantation management strategies for adult patients listed for lung transplantation.

A Composite End Point of Graft Status and eGFR at 1 Year to Improve the Scientific Registry of Transplant Recipients' Five-Tier Rating System

BACKGROUND

Performance of kidney transplant programs in the United States is monitored and publicly reported by the Scientific Registry of Transplant Recipients (SRTR). With relatively few allograft failure events per program and increasing homogeneity in program performance, quantifying meaningful differences in program competency based only on 1-year survival rates is challenging.

METHODS

We explored whether the traditional end point of allograft failure at 1 year can be improved by incorporating a measure of allograft function (i.e., eGFR) into a composite end point. We divided SRTR data from 2008 through 2018 into a training and validation set and recreated SRTR tiers, using the traditional and composite end points. The conditional 5-year deceased donor allograft survival and 5-year eGFR were then assessed using each approach.

RESULTS

Compared with the traditional end point, the composite end point of graft failure or eGFR <30 ml/min per 1.73 m² at 1-year post-transplant performed better in stratifying transplant programs based on long-term deceased donor graft survival. For tiers 1 through 5 respectively, the 5-year conditional graft survival was 72.9%, 74.8%, 75.4%, 77.0%, and 79.7% using the traditional end point and 71.1%, 74.4%, 76.9%, 77.0%, and 78.4% with the composite end point. Additionally, with the five-tier system derived from the composite end point, programs in tier 3, tier 4, and tier 5 had significantly higher mean eGFRs at 5 years compared with programs in tier 1. There were no significant eGFR differences among tiers derived from the traditional end point alone.

CONCLUSIONS

This proof-of-concept study suggests that a composite end point incorporating allograft function may improve the post-transplant component of the five-tier system by better differentiating between transplant programs with respect to long-term graft outcomes.

The Lung Allocation Score and Other Available Models Lack Predictive Accuracy for Post-Lung Transplant Survival

BACKGROUND

Improved predictive models are needed in lung transplantation in the setting of a proposed allocation system that incorporates longer-term post-transplant survival in the United States. Allocation systems require accurate mortality predictions to justly allocate organs.

METHODS

Utilizing the United Network for Organ Sharing database (2005-2017), we fit models to predict 1-year mortality based on the Lung Allocation Score (LAS), the Chan, et al, 2019 model, a novel "clinician" model (a priori clinician selection of pre-transplant covariates), and two machine learning models (Least Absolute Shrinkage and Selection Operator; LASSO and Random Forests) for predicting 1-year and 3-year post-transplant mortality. We compared predictive accuracy among models. We evaluated the calibration of models by comparing average predicted probability vs observed outcome per decile. We repeated analyses fit for 3-year mortality, disease category, including donor covariates, and LAS era.

RESULTS

The area under the cure for all models was low, ranging from 0.55 to 0.62. All exhibited reasonable negative predictive values (0.87-0.90), but the positive predictive value for was poor (all <0.25). Evaluating LAS calibration found 1-year post-transplant estimates consistently overestimated risk of mortality, with greater differences in higher deciles. LASSO, Random Forests, and clinician models showed no improvement when evaluated by disease category or with the addition of donor covariates and performed worse for 3-year outcomes.

CONCLUSIONS

The LAS overestimated patients' risk of post-transplant death, thus underestimating transplant benefit in the sickest candidates. Novel models based on pre-transplant recipient covariates failed to improve prediction. There should be wariness in post-transplant survival predictions from available models.

Donor leukocyte trafficking during human ex vivo lung perfusion

Background

Ex vivo lung perfusion (EVLP) is used to assess and preserve lungs prior to transplantation. However, its inherent immunomodulatory effects are not completely understood. We examine perfusate and tissue compartments to determine the change in immune cell composition in human lungs maintained on EVLP.

Methods

Six human lungs unsuitable for transplantation underwent EVLP. Tissue and perfusate samples were obtained during cold storage and at 1‐, 3‐ and 6‐h during perfusion. Flow cytometry, immunohistochemistry, and bead‐based immunoassays were used to measure leukocyte composition and cytokines. Mean values between baseline and time points were compared by Student's t test.

Results

During the 1st hour of perfusion, perfusate neutrophils increased (+22.2 ± 13.5%, p < 0.05), monocytes decreased (−77.5 ± 8.6%, p < 0.01) and NK cells decreased (−61.5 ± 22.6%, p < 0.01) compared to cold storage. In contrast, tissue neutrophils decreased (−22.1 ± 12.2%, p < 0.05) with no change in monocytes and NK cells. By 6 h, perfusate neutrophils, NK cells, and tissue neutrophils were similar to baseline. Perfusate monocytes remained decreased, while tissue monocytes remained unchanged. There was no significant change in B cells or T cell subsets. Pro‐inflammatory cytokines (IL‐1b, G‐CSF, IFN‐gamma, CXCL2, CXCL1 granzyme A, and granzyme B) and lymphocyte activating cytokines (IL‐2, IL‐4, IL‐6, IL‐8) increased during perfusion.

Conclusions

Early mobilization of innate immune cells occurs in both perfusate and tissue compartments during EVLP, with neutrophils and NK cells returning to baseline and monocytes remaining depleted after 6 h. The immunomodulatory effect of EVLP may provide a therapeutic window to decrease the immunogenicity of lungs prior to transplantation.

Delayed mortality among solid organ transplant recipients hospitalized for COVID-19

INTRODUCTION

Most studies of solid organ transplant (SOT) recipients with COVID-19 focus on outcomes within one month of illness onset. Delayed mortality in SOT recipients hospitalized for COVID-19 has not been fully examined.

METHODS

We used data from a multicenter registry to calculate mortality by 90 days following initial SARS-CoV-2 detection in SOT recipients hospitalized for COVID-19 and developed multivariable Cox proportional-hazards models to compare risk factors for death by days 28 and 90.

RESULTS

Vital status at day 90 was available for 936 of 1117 (84%) SOT recipients hospitalized for COVID-19: 190 of 936 (20%) died by 28 days and an additional 56 of 246 deaths (23%) occurred between days 29 and 90. Factors associated with mortality by day 90 included: age > 65 years [aHR 1.8 (1.3-2.4), p =<0.001], lung transplant (vs. non-lung transplant) [aHR 1.5 (1.0-2.3), p=0.05], heart failure [aHR 1.9 (1.2-2.9), p=0.006], chronic lung disease [aHR 2.3 (1.5-3.6), p<0.001] and body mass index ≥ 30 kg/m 2 [aHR 1.5 (1.1-2.0), p=0.02]. These associations were similar for mortality by day 28. Compared to diagnosis during early 2020 (March 1-June 19, 2020), diagnosis during late 2020 (June 20-December 31, 2020) was associated with lower mortality by day 28 [aHR 0.7 (0.5-1.0, p=0.04] but not by day 90 [aHR 0.9 (0.7-1.3), p=0.61].

CONCLUSIONS

In SOT recipients hospitalized for COVID-19, >20% of deaths occurred between 28 and 90 days following SARS-CoV-2 diagnosis. Future investigations should consider extending follow-up duration to 90 days for more complete mortality assessment.

Assessing the accuracy of the lung allocation score

BACKGROUND

The United States (US) Lung Allocation Score (LAS) relies on the performance of 2 survival models that estimate waitlist and post-transplant survival. These models were developed using data from 2005 to 2008, and it is unknown if they remain accurate.

METHODS

We performed an observational cohort study of US lung transplantation candidates and recipients greater than 12 years of age between February 19, 2015 and February 19, 2019. We evaluated the LAS waitlist and post-transplant models with the concordance probability estimate and by comparing predicted vs observed 1-year restricted mean survival times by risk decile. We then compared a nonparametric estimate of the observed LAS with the predicted LAS for each percentile of recipients.

RESULTS

The waitlist model ranked candidates (N = 11,539) in the correct risk order 72% of the time (95% CI 71%-73%), and underestimated candidate one-year survival by 136 days for the highest risk decile (p < 0.001). The post-transplant model ranked recipients (N = 9,377) in the correct risk order 57% of the time (95% CI 55-58%), and underestimated recipient one-year survival by 70 days for the highest risk decile (p < 0.001). Overall, the LAS at transplant explained only 56% of the variation in observed outcomes, and was increasingly inaccurate at higher predicted values.

CONCLUSIONS

The waitlist and the post-transplant models that constitute the LAS are inaccurate, limiting the ability of the system to rank candidates on the waitlist in the correct order. The LAS should therefore be updated and the underlying models should be modernized.

Mortality after Lung Transplantation for Children Bridged with Extracorporeal Membrane Oxygenation

RATIONALE

Extracorporeal membrane oxygenation (ECMO) is increasingly used to bridge waitlisted children failing conventional respiratory support to lung transplantation.

OBJECTIVES

To compare in-hospital mortality and a composite outcome of 1-year mortality or re-transplantation in children bridged with ECMO with those on mechanical ventilation (MV), and neither support.

METHODS

The United Network for Organ Sharing (UNOS) was used to analyze lung transplant recipients, aged ≤ 20 y, from January 2004 to August 2019. Recipients were categorized according to level of respiratory support at time of transplant, including ECMO, MV, or neither. Multivariable analysis was used to evaluate support type and in-hospital mortality.

RESULTS

Of 1,014 children undergoing lung transplant, 68 (6.7%) required ECMO as a bridge-to-transplant, 144 (14.2%) MV, and 802 (79.1%) neither. Primary diagnosis in the ECMO cohort included cystic fibrosis (43%), pneumonia/ARDS (10.3%), interstitial pulmonary fibrosis (7.4%) and pulmonary hypertension (5.9%). Number of patients bridged with ECMO increased throughout the study period from none in 2004 to 16.7% in 2018. Multivariable analysis showed bridging with both ECMO (aOR = 3.57; 95% CI: 1.42, 8.97) and MV (aOR = 2.67; 95% CI: 1.26, 5.57) increased in-hospital mortality after lung transplantation. However, there was no difference in composite outcome of mortality and re-transplantation at 1-year between the three groups.

CONCLUSIONS

ECMO to bridge children to lung transplantation has increased. Despite this, ECMO is a high-risk bridge strategy for children awaiting lung transplantation. Future research should target interventions that can be focused on improving survival in these patients.

Mitigating selection bias in organ allocation models

Background

The lung allocation system in the U.S. prioritizes lung transplant candidates based on estimated pre- and post-transplant survival via the Lung Allocation Scores (LAS). However, these models do not account for selection bias, which results from individuals being removed from the waitlist due to receipt of transplant, as well as transplanted individuals necessarily having survived long enough to receive a transplant. Such selection biases lead to inaccurate predictions.

Methods

We used a weighted estimation strategy to account for selection bias in the pre- and post-transplant models used to calculate the LAS. We then created a modified LAS using these weights, and compared its performance to that of the existing LAS via time-dependent receiver operating characteristic (ROC) curves, calibration curves, and Bland-Altman plots.

Results

The modified LAS exhibited better discrimination and calibration than the existing LAS, and led to changes in patient prioritization.

Conclusions

Our approach to addressing selection bias is intuitive and can be applied to any organ allocation system that prioritizes patients based on estimated pre- and post-transplant survival. This work is especially relevant to current efforts to ensure more equitable distribution of organs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01379-7.

Waiting List Dynamics and Lung Transplantation Outcomes After Introduction of the Lung Allocation Score in The Netherlands

Supplemental Digital Content is available in the text.

The Netherlands was the third country to adopt the lung allocation score (LAS) for national allocation of donor lungs in April 2014. Evaluations of the introduction of the LAS in the United States and Germany showed mainly beneficial effects, including increased survival after transplantation.

Construct and Predictive Validity of Sarcopenia in Lung Transplant Candidates

Rationale: Sarcopenia is associated with disability and death. The optimal definition and clinical relevance of sarcopenia in lung transplantation remain unknown. Objectives: To assess the construct and predictive validity of sarcopenia definitions in lung transplant candidates. Methods: In a multicenter prospective cohort of 424 lung transplant candidates, we evaluated limited (muscle mass only) and expanded (muscle mass and quality) sarcopenia definitions from the European Working Group on Sarcopenia in Older People 2 (EWGSOP2), the Foundation for the National Institutes of Health (FNIH), and a cohort-specific distribution-based lowest quartile definition. We assessed construct validity using associations with conceptually related factors. We evaluated the relationship between sarcopenia and frailty using generalized additive models. We also evaluated associations between sarcopenia definitions and key pretransplant outcomes, including disability (quantified by the Lung Transplant Valued Life Activities scale [range, 0-3; higher scores = worse disability; minimally important difference, 0.3]) and waitlist delisting/death, by multivariate linear and Cox regression, respectively. Results: Sarcopenia prevalence ranged from 6% to13% by definition used. The limited EWGSOP2 definition demonstrated the highest construct validity, followed by the expanded EWGSOP2 definition and both limited and expanded FNIH and lowest quartile definitions. Sarcopenia exhibited a linear association with the risk of frailty. The EWGSOP2 and expanded lowest quartile definitions were associated with disability, ranging from 0.20 to 0.25 higher Lung Transplant Valued Life Activities scores. Sarcopenia was associated with increased risk of waitlist delisting or death by the limited and expanded lowest quartile definitions (hazard ratio [HR], 3.8; 95% confidence interval [CI], 1.4-9.9 and HR, 3.5; 95% CI, 1.1-11.0, respectively) and the EWGSOP2 limited definition (HR, 2.8; 95% CI, 0.9-8.6) but not with the three other candidate definitions. Conclusions: The prevalence and validity of sarcopenia vary by definition; the EWGSOP2 limited definition exhibited the broadest validity in lung transplant candidates. The linear relationship between low muscle mass and frailty highlights sarcopenia's contribution to frailty and also questions the clinical utility of a sarcopenia cut-point in advanced lung disease. The associations between sarcopenia and important pretransplant outcomes support further investigation into using body composition for candidate risk stratification.

Inpatient Lung Transplant Evaluation Is Associated With Increased Risk of Morbidity, Mortality, and Cost of Care After Transplant

Lung transplantation is an important option for patients with end-stage lung disease. Many of these patients deteriorate rapidly and require inpatient care at the time of the transplant evaluation.

RESEARCH QUESTION

How does the setting of lung transplant evaluation relate to perioperative outcomes, short-term postoperative outcomes, and healthcare costs accrued after transplant?

DESIGN

We reviewed the records of patients who underwent primary, bilateral lung transplantation at our center between January 1, 2014 and May 31, 2016. Patient evaluation setting was categorized as inpatient, outpatient, or combined. Demographics, clinical characteristics, and cost of care were assessed.

RESULTS

The study included 207 patients: 40 (19.3%) evaluated as inpatients, 146 (70.5%) as outpatients, and 21 (10.1%) as combined. Inpatients had the highest mean lung allocation scores (71.2 vs 49.7 [combined] and 40.8 [outpatient]; P < 0.001), lowest functional status at listing (P < 0.001), highest number of blood products used during surgery (P < 0.001), highest incidence of re-exploration for bleeding (P = 0.006), and longest posttransplant hospital stays (median, 35 vs 15 days [combined] and 12 days [outpatient]; P < 0.001). One-year survival trended lower for inpatients (log-rank, P = 0.056). Inpatient evaluations had the highest total, variable, and fixed costs of posttransplant care (P < 0.001).

CONCLUSION

Inpatient lung transplant evaluation was associated with longer hospital stays, higher perioperative morbidity, and lower 1-year survival. Partial or complete inpatient evaluation was associated with a higher cost of care posttransplant.

The Lung Allocation Score and Its Relevance

Lung transplantation in the United States, under oversight by the Organ Procurement Transplantation Network (OPTN) in the 1990s, operated under a system of allocation based on location within geographic donor service areas, wait time of potential recipients, and ABO compatibility. On May 4, 2005, the lung allocation score (LAS) was implemented by the OPTN Thoracic Organ Transplantation Committee to prioritize patients on the wait list based on a balance of wait list mortality and posttransplant survival, thus eliminating time on the wait list as a factor of prioritization. Patients were categorized into four main disease categories labeled group A (obstructive lung disease), B (pulmonary hypertension), C (cystic fibrosis), and D (restrictive lung disease/interstitial lung disease) with variables within each group impacting the calculation of the LAS. Implementation of the LAS led to a decrease in the number of wait list deaths without an increase in 1-year posttransplant survival. LAS adjustments through the addition, modification or elimination of covariates to improve the estimates of patient severity of illness, have since been made in addition to establishing criteria for LAS value exceptions for pulmonary hypertension patients. Despite the success of the LAS, concerns about the prioritization, and transplantation of older, sicker individuals have made some aspects of the LAS controversial. Future changes in US lung allocation are anticipated with the current development of a continuous distribution model that incorporates the LAS, geographic distribution, and unaccounted aspects of organ allocation into an integrated score.

Performance Changes Following the Revision of Organ Allocation System of Lung Transplant: Analysis of Korean Network for Organ Sharing Data

BACKGROUND

There is currently a lack of data on the impact of the recent revision of the domestic lung allocation system on transplant performance.

METHODS

We conducted a retrospective analysis of transplant candidates and transplant patients registered in Korean Network for Organ Sharing between July 2015 and July 2019. Study periods were classified according to the introduction of the revised lung allocation system as follows: period 1 from July 2015 to June 2017 and period 2 from August 2017 to July 2019.

RESULTS

During the study period, a total of 627 patients were on the waiting list, of which 398 lung transplantations were performed. Total waiting list size increased by 98.6%, from 210 in period 1 to 417 in period 2. The number of transplant patients also increased by 32.7%, from 171 in period 1 to 227 in period 2. The number of donors decreased from 1,042 to 878, whereas the usage rate, i.e., the number of lung donors used for transplantation among the total number of reported lung donors, increased from 16.4% to 25.9%. The proportion of patients with high urgent status at transplantation increased from 45% to 60.4%, whereas those with urgent status decreased from 46.8% to 35.7% (P = 0.006). The use of marginal donor lungs increased from 29.8% to 53.7% (P < 0.001). To adjust urgency status and marginal donor usage between two groups, we conducted a propensity score matching analysis. No significant differences were detected in 1-year survival rates between the two periods after propensity score matching. As well, no significant difference was observed in mortality on the waiting list between the two periods.

CONCLUSION

The recent revision of the lung allocation system in Korea did not change the performance of lung transplant in terms of waiting list mortality and 1-year survival. The rapid increase in the volume of waiting list between the two periods increased the waiting time, transplantation of high-urgency patients, and use of marginal lung donors.

Factors Related to Survival in Low-Glomerular Filtration Rate Cohorts Undergoing Lung Transplant

BACKGROUND

Historically, a glomerular filtration rate (GFR) of less than 50 mL/min per 1.73 m² has been considered a contraindication to lung transplantation. Combined or sequential lung-kidney transplantation is an option for those with a GFR less than 30 mL/min per 1.73 m². Patients with a GFR of 30 to 50 mL/min per 1.73 m² are provided with no options for transplantation. This study explores factors associated with improved survival in patients who undergo isolated lung transplantation with a GFR of 30 to 50 mL/min per 1.73 m².

METHODS

The United Network for Organ Sharing database was queried for adult patients undergoing primary isolated lung transplantation between January 2007 and March 2018. Regression models were used to identify factors associated with improved survival in lung recipients with a preoperative GFR of 30 to 50 mL/min per 1.73 m². The propensity score method was used to match highly performing patients (outpatient recipients aged less than 60 years) with a GFR of 30 to 50 mL/min per 1.73 m² with patients who had a GFR greater than 50 mL/min per 1.73 m². Kaplan-Meier, Cox, and logistic regression analyses compared outcomes in matched populations.

RESULTS

A total of 21,282 lung transplantations were performed during the study period. Compared with patients with a GFR greater than 50 mL/min per 1.73 m², survival was significantly worse for patients with a GFR of 30 to 50 mL/min per 1.73 m². Multivariate analysis of patients with a GFR of 30 to 50 mL/min per 1.73 m² demonstrated outpatient status and age less than 60 years to be predictive of superior survival. After propensity matching, survival of this highly performing subset with a GFR of 30 to 50 mL/min per 1.73 m² was no different from that of patients with a normal GFR.

CONCLUSIONS

Outpatient recipients aged less than 60 years represent an optimal subset of patients with a GFR of 30 to 50 mL/min per 1.73 m². Lung transplant listing should not be declined based only on a GFR less than 50 mL/min per 1.73 m².

Clinical judgment versus lung allocation score in predicting lung transplant waitlist mortality

Canadian lung transplant centers currently use a subjective and dichotomous "Status" ranking to prioritize waitlisted patients for lung transplantation. The lung allocation score (LAS) is an objective composite score derived from clinical parameters associated with both waitlist and post-transplant survival. We performed a retrospective cohort study to determine whether clinical judgment (Status) or LAS better predicted waitlist mortality. All adult patients listed for lung transplantation between 2007 and 2012 at three Canadian lung transplant programs were included. Status and LAS were compared in their ability to predict waitlist mortality using Cox proportional hazards models and C-statistics. Status and LAS were available for 1122 patients. Status 2 patients had a higher LAS compared to Status 1 patients (mean 40.8 (4.4) vs 34.6 (12.5), P = .0001). Higher LAS was associated with higher risk of waitlist mortality (HR 1.06 per unit LAS, 95% CI 1.05, 1.07, P < .001). LAS predicted waitlist mortality better than Status (C-statistic 0.689 vs 0.674). Patients classified as Status 2 and LAS ≥ 37 had the worst survival awaiting transplant, HR of 8.94 (95% CI 5.97, 13.37). LAS predicted waitlist mortality better than Status; however, the best predictor of waitlist mortality may be a combination of both LAS and clinical judgment.

Improved survival after lung transplantation for adults requiring preoperative invasive mechanical ventilation: A national cohort study

OBJECTIVE

Early survival after lung transplantation has improved in the last decade. Mechanically ventilated recipients are known to be at greater risk for early post-transplant mortality. We hypothesized that post-transplant survival in mechanically ventilated recipients has improved over time.

METHODS

Using a national registry, we compared hazard of death at 30 days, 4 and 14 months, 3 and 5 years, and overall for adults on mechanical ventilation who underwent lung or heart-lung transplantation from May 4, 2011, to April 4, 2018 (modern group) with those undergoing transplantation from May 4, 2005, to May 3, 2011 (early group). We quantified the impact of mechanical ventilation on survival using population-attributable fractions. We also compared mechanically ventilated recipients with nonmechanically ventilated recipients.

RESULTS

Mechanically ventilated recipients from the modern group had lower hazard of death than recipients in the early group at all time-points, lowest at 30-days post-transplant (hazard ratio, 0.04; 95% confidence interval, 0.02-0.08). In the modern period, mechanically ventilated recipients had greater hazard of death than nonmechanically ventilated recipients at 30 days' post-transplant (9.53; 4.57-19.86). For mechanically ventilated recipients, the population attributable fraction was lower in the modern group compared to the earlier group (0.6% vs 5.7%).

CONCLUSIONS

While mechanically ventilated recipients remain at high risk, survival in this patient population has improved over time. This may reflect improvements in perioperative recipient management.

Donor Leukocyte Trafficking and Damage-associated Molecular Pattern Expression During Ex Vivo Lung Perfusion

Background.

While ex vivo lung perfusion (EVLP) has become established in lung transplantation, the cellular processes occurring during this period are not yet fully understood. Prior studies demonstrated that donor leukocytes (DLs) migrate from the graft into the perfusate during EVLP, but the distribution of DLs in graft and perfusate compartments has not been characterized. Moreover, cell death of DLs has been implicated in mediating graft injury during EVLP, but the underlying mechanisms have not been elucidated. We hypothesized the following: (1) there is a nonspecific migration of DLs from the graft into perfusate and (2) cell death of DLs releases damage-associated molecular patterns (DAMPs) that contribute to the inflammatory milieu during EVLP.

Methods.

EVLP was performed on rat lungs for 3 hours (N = 6). At the end of EVLP, flow cytometry was used to quantify the distribution of different DL cell types in both the graft and perfusate compartments. During EVLP, the perfusate was also sampled hourly to measure levels of DAMPs and downstream inflammatory cytokines generated during EVLP.

Results.

At the conclusion of EVLP, there was a significantly higher proportion of T and B cells present in the perfusate compartment compared with the graft compartment. There was a time-dependent increase in extracellular DNA and tumor necrosis factor α in the perfusate during EVLP.

Conclusions.

T cells and B cells are enriched in the perfusate compartment during EVLP. Cell death of DLs contributes to an accumulation of DAMPs during EVLP.

Impact of donor, recipient and matching on survival after high emergency lung transplantation in France

INTRODUCTION

Since July 2007, the French high emergency lung transplantation (HELT) allocation procedure prioritises available lung grafts to waiting patients with imminent risk of death. The relative impacts of donor, recipient and matching on the outcome following HELT remain unknown. We aimed at deciphering the relative impacts of donor, recipient and matching on the outcome following HELT in an exhaustive administrative database.

METHODS

All lung transplantations performed in France were prospectively registered in an administrative database. We retrospectively reviewed the procedures performed between July 2007 and December 2015, and analysed the impact of donor, recipient and matching on overall survival after the HELT procedure by fitting marginal Cox models.

RESULTS

During the study period, 2335 patients underwent lung transplantation in 11 French centres. After exclusion of patients with chronic obstructive pulmonary disease/emphysema, 1544 patients were included: 503 HELT and 1041 standard lung transplantation allocations. HELT was associated with a hazard ratio for death of 1.41 (95% CI 1.22-1.64; p<0.0001) in univariate analysis, decreasing to 1.32 (95% CI 1.10-1.60) after inclusion of recipient characteristics in a multivariate model. A donor score computed to predict long-term survival was significantly different between the HELT and standard lung transplantation groups (p=0.014). However, the addition of donor characteristics to recipient characteristics in the multivariate model did not change the hazard ratio associated with HELT.

CONCLUSIONS

This exhaustive French national study suggests that HELT is associated with an adverse outcome compared with regular allocation. This adverse outcome is mainly related to the severity status of the recipients rather than donor or matching characteristics.

Clinical outcomes and survival following lung transplantation in patients with pulmonary Langerhans cell histiocytosis

BACKGROUND AND OBJECTIVE

Disease-specific outcomes following lung transplantation (LT) in patients with pulmonary Langerhans cell histiocytosis (PLCH) are not well established. We queried the Organ Procurement and Transplantation Network database to identify adult PLCH patients who had undergone LT in the United States.

METHODS

Overall survival data were analysed with Kaplan-Meier curves. Cox proportional hazard model was used to determine the effect of demographic, clinical and physiological variables on post-transplant survival.

RESULTS

A total of 87 patients with PLCH underwent LT in the United States between October 1987 and June 2017, accounting for 0.25% of the total LT during this period. The mean age at LT for PLCH patients was 49 years (range: 19-67 years), with a near equal gender distribution. Bilateral sequential LT was performed in 71 patients (82%). Pulmonary hypertension was present in 85% of patients, with a mean pulmonary artery pressure of 38.5 ± 14.1 mm Hg. The mean pre-transplant forced expiratory volume in 1 s (FEV₁ ) was 41 ± 21% predicted and the mean 6-min walk distance was 221 ± 111 m. Median post-LT survival for PLCH patients was comparable to patients with other lung diseases (5.1 vs 5.5 years, P = 0.76). The actuarial Kaplan-Meier post-LT survival for PLCH patients was 85%, 65%, 49% and 22% at 1, 3, 5 and 10 years, respectively. Female sex (hazard ratio (HR): 0.40, 95% CI: 0.22-0.72), pre-transplant serum bilirubin (HR: 1.66, 95% CI: 1.23-2.26) and serum creatinine (HR: 4.03, 95% CI: 1.01-14.76) were independently associated with post-LT mortality in our cohort.

CONCLUSION

Post-LT survival in patients with PLCH is similar to patients with other lung diseases and is significantly affected by patient gender.

Utilization and Cost Analysis of Lung Transplantation and Survival After 10 Years of Adapting the Lung Allocation Score

BACKGROUND

Lungs are allocated in the United States using the lung allocation score (LAS). We investigated the effect of LAS trends on lung transplant-related costs, healthcare utilization, and mortality.

METHODS

Utilization data from Mayo Clinic (Florida and Minnesota) from 2005 to 2015 were obtained from the electronic health records (N = 465). Costs were categorized as 1-year posttransplant or transplant episode and standardized using 2015 Medicare reimbursement and cost-to-charge ratios. Regression analysis was used to assess the relationship of LAS to length of stay (LOS), mortality, and cost of transplant.

RESULTS

The mean LAS at transplant increased from 45.7 to 58.3 during the study period, whereas the 1-year survival improved from 88.1% to 92.5% (P < 0.0001). The proportion of patients transplanted with LAS of 60 or greater increased from 16.9% to 33.3%. Posttransplant, overall, and intensive care unit LOS increased with increasing LAS. Patients with higher LAS had substantially higher transplant episode costs. An increase of LAS at transplant by 10 points increased inflation-adjusted costs by 12.0% (95% confidence interval, 9.3%-14.5%).

CONCLUSIONS

The mean LAS at transplant has significantly increased over time associated with increases in LOS, resource utilization and cost. Lung allocation score has not jeopardized overall survival, but a high LAS (>60) at transplant is associated with increased mortality.

An Ethical Framework for the Care of Patients with Prolonged Hospitalization Following Lung Transplantation

The lung allocation score system in the United States and several European countries gives more weight to risk of death without transplantation than to survival following transplantation. As a result, centers transplant sicker patients, leading to increased length of initial hospitalization. The care of patients who have accumulated functional deficits or additional organ dysfunction during their prolonged stay can be ethically complex. Disagreement occurs between the transplant team, patients and families, and non-transplant health care professionals over the burdens of ongoing intensive intervention. These cases highlight important ethical issues in organ transplantation, including the nature and requirements of transplant informed consent, the limits of physician prognostication, patient autonomy and decision-making capacity following transplant, obligations to organ donors and to other potential recipients, and the impact of program metrics on individualized recipient care. We outline general ethical principles for the care of lung transplant recipients with prolonged hospitalization and give regulatory, research, and patient-centered recommendations for these cases.

Clinical outcomes and survival following lung transplantation in patients with lymphangioleiomyomatosis

BACKGROUND

The primary aim of our study was to derive disease-specific outcomes following lung transplantation (LT) in patients with lymphangioleiomyomatosis (LAM).

METHODS

We queried the Organ Procurement and Transplant Network database to identify LAM patients that have undergone LT in the United States. The overall survival was analyzed with Kaplan-Meier curves. Survival estimates between subgroups of interest were compared using the log-rank method. Cox proportional hazard models were employed to determine the pre-transplant variables that impact post-LT survival.

RESULTS

One hundred and thirty-eight women with LAM underwent LT at 31 centers between January 2003 and June 2017. The median age at listing and transplant was 44 (IQR: 36-51) and 45 (IQR: 38-52) years, respectively. The median time spent on the LT waitlist was 257 (IQR: 85-616) days. The majority of the patients (109/134, 81%) received bilateral sequential LT. The median ischemic time was 4.9 (IQR: 4.1-6.1) hours. The actuarial Kaplan-Meier survival following LT for LAM patients at 1-, 5-, and 10 years was 94%, 73% and 56%, respectively. The post-LT survival was significantly better in LAM than in other lung diseases (10-year survival 56% vs. 32%, p < 0.01), and this advantage persisted after age- and gender-matched analysis (10-year survival 54% vs. 37%, p < 0.01). Pre-transplant parameters, such as the presence of pulmonary hypertension, six-minute walk distance, age at transplant, ischemic time during transplant, or type of transplant (single vs bilateral sequential LT), did not affect post-transplant survival.

CONCLUSIONS

The median survival after LT in LAM is 12 years and is substantially better than in other lung diseases.

Aligning use of intensive care with patient values in the USA: past, present, and future

For more than three decades, both medical professionals and the public have worried that many patients receive non-beneficial care in US intensive care units during their final months of life. Some of these patients wish to avoid severe cognitive and physical impairments, and protracted deaths in the hospital setting. Recognising when intensive care will not restore a person's health, and helping patients and families embrace goals related to symptom relief, interpersonal connection, or spiritual fulfilment are central challenges of critical care practice in the USA. We review trials from the past decade of interventions designed to address these challenges, and present reasons why evaluating, comparing, and implementing these interventions have been difficult. Careful scrutiny of the design and interpretation of past trials can show why improving goal concordant care has been so elusive, and suggest new directions for the next generation of research.

Characteristics, Trends, and Predictors of Specialty Palliative Care Utilization after Lung Transplantation

Background: Lung transplant recipients who experience serious illness could benefit from specialty palliative care (SPC), but evidence suggests that referral has been rare. Objective: Examine the characteristics of post-transplant SPC encounters, utilization trends, and patient characteristics associated with SPC at a center with established SPC services. Design: Retrospective cohort study of SPC utilization by 597 lung transplant recipients transplanted between 2010 and 2015. We collected data on pretransplant demographics and post-transplant SPC encounters, including timing, location, and referral reasons. Cumulative incidence of SPC and patient characteristics associated with SPC were examined by competing risks methods. Utilization in the first two post-transplant years was compared between subcohorts defined by year of transplantation. Results: SPC cumulative incidence was 27% and 43% at one and five years. More than 60% of encounters occurred in the first post-transplant year including 34% during the index transplant hospitalization. Over 90% of encounters occurred in the inpatient setting. The majority of consults were for symptom management. From 2010 to 2015 inpatient utilization in the first two post-transplant years increased from 23% to 42%, and outpatient utilization increased from 2% to 16%. Accounting for increasing utilization, pretransplant SPC and double-lung transplantation were associated with greater incidence of post-transplant SPC. Conclusions: Lung transplant recipients may have palliative care needs early after transplantation. Increasing utilization suggests greater awareness of or changing attitudes about the utility of SPC for lung transplant recipients. Understanding transplant recipients' palliative care needs and transplant physicians' views of SPC is critical to improving the provision of SPC in lung transplantation.

The lung allocation score could evaluate allocation systems in countries that do not use the score

BACKGROUND

Evaluating allocation system effects on lung transplantation and determining systemic flaws is difficult. The purpose of this study was to assess the Korean urgency-based lung allocation system using the lung allocation score.

METHODS

We reviewed transplantation patients retrospectively. Candidates were classified into groups based on urgency. Status 0 designated hospitalized patients requiring ventilator and/or extracorporeal life support. The lung allocation score was calculated based on the recipient's condition at transplantation.

RESULTS

One-hundred-twenty-three Status 0, 1, and 2/3 patients (40, 71, and 12, respectively) were enrolled. The median waiting time was 68 days. Nineteen Status 0 patients who received lung transplants deteriorated from non-Status 0 (median, 64 days). The lung allocation score showed a bimodal distribution (peaks around 45 and 90, corresponding with non-Status 0 and Status 0, respectively). Status 0 and the lung allocation score were independent risk factors for poor survival after adjustment for confounders (Status 0, hazard ratio, 2.788, p = 0.001; lung allocation score, hazard ratio, 1.025, p < 0.001). The lung allocation score cut-off for survival was 44. On dividing the non-Status 0 patients into 2 groups using the cut-off values and regrouping into Status 0, non-Status 0 with high lung allocation score (> 44), and non-Status 0 with low lung allocation score (< 44), we observed that non-Status 0 with high lung allocation score patients had better survival than Status 0 patients (p = 0.020) and poorer survival than non-Status 0 with low lung allocation score patients (p = 0.018).

CONCLUSIONS

The LAS demonstrated the characteristics of LTx recipients in Korea and the Korean allocation system needs to be revised to reduce the number of patients receiving LTx in Status 0. The LAS system could be used as a tool to evaluate lung allocation systems in countries that do not use the LAS system.

In-hospital and subsequent mortality among lung transplant recipients with a prolonged initial hospitalization

The care of lung transplant recipients with prolonged index hospitalizations can be ethically complex, with conflicts arising over whether the expected outcomes justify ongoing intensive interventions. There are limited data to guide these conversations. The objective of this study was to evaluate survival to discharge for lung transplant recipients based on length of stay (LOS). This was a retrospective cohort study of adult lung transplant recipients in the Scientific Registry of Transplant Recipients. For each day of the index hospitalization the mortality rate among patients who survived to that length of stay or longer was calculated. Post-discharge survival was compared in those with and without a prolonged hospitalization (defined as the 97th percentile [>90 days]). Among the 19 250 included recipients, the index hospitalization mortality was 5.4%. Posttransplant stroke and need for dialysis were the strongest predictors of index hospitalization mortality. No individual or combination of available risk factors, however, was associated with inpatient mortality consistently above 50%. Recipients with >90 day index hospitalization had a 28.8% subsequent inpatient mortality. Their 1, 3 and 5 year survival following discharge was 53%, 26%, and 16%. These data provide additional context to goals of care conversations for transplant recipients with prolonged index hospitalizations.

Lung Allocation Score Thresholds Prioritize Survival After Lung Transplantation

BACKGROUND

The lung allocation score (LAS) prioritizes lung transplant (LTx) candidates with poor transplant-free survival and expected survival benefit from LTx. Although patients with the highest LAS have the shortest waiting time, mortality benefit is unclear in this group, raising criticism that the LAS inappropriately prioritizes critically ill candidates. We aim to identify a threshold above which increasing LAS values do not predict increasing survival benefit.

METHODS

The United Network for Organ Sharing Registry was queried for first-time adult LTx candidates with LAS ≥ 30 between May 2005 and December 2016. Survival was tracked from the time of listing through the posttransplant period and compared with survival while remaining on the waitlist, using proportional hazards regression. The survival benefit of LTx was modeled as a piecewise-constant time-dependent covariate, moderated by candidate LAS.

RESULTS

Of the overall cohort (N = 21,157), LTx was particularly protective for 365 patients with an initial LAS of 70 to 79 (hazard ratio of death after undergoing LTx relative to remaining on the waitlist, 0.2; 95% CI, 0.1-0.3). However, the survival benefit of LTx did not meaningfully increase for 1,042 patients listed with even higher LAS. Among patients with cystic fibrosis, the survival benefit of LTx was constant above an LAS of approximately 50.

CONCLUSIONS

Consistent survival benefit of LTx was observed among patients with an initial LAS of 70 and greater. This result supports equalizing priority for donor lung allocation for patients with LAS ≥ 70. A lower LAS threshold for maximum priority is indicated in patients with cystic fibrosis.

National Heart, Lung, and Blood Institute and American Association for Thoracic Surgery Workshop Report: Identifying collaborative clinical research priorities in lung transplantation

This report summarizes the discussion and recommendations from the June 2017 NHLBI-AATS Workshop on Identifying Collaborative Clinical Research Priorities in Lung Transplantation.

Lung Transplantation in Germany Since the Introduction of the Lung Allocation Score

BACKGROUND

The allocation of donor lungs for transplantation in Germany was changed on 10 December 2011 to a system based on the Lung Allocation Score (LAS). The aim of the present study is to determine whether this change has prolonged the survival of patients on the transplant waiting list and of those who have undergone lung transplantation (LTx).

METHODS

We retrospectively compared data from the three-year periods before and after the change to an LAS-based allocation system (2009-2011 vs. 2012-2014).

RESULTS

The number of patients on the active waiting list declined from 606 on 12/31/2011 to 432 on 12/31/2014, a 29% decrease. The number of patients who died while on the waiting list fell from 306 in 2009-2011 to 226 in 2012-2014 (-26%, p = 0.04). Waiting-list mortality declined across all disease groups. Meanwhile, the number of lung transplantation procedures per year increased by 21% over the period of observation, from 865 to 1045. During the period in which the LAS was used, the proportion of transplant recipients with restrictive lung disease (46% vs. 31%; p<0.001) surpassed the proportion of those with a diagnosis of obstructive lung disease (33% vs. 40%; p = 0.003). The percentage of transplantations in patients treated with mechanical ventilation or extracorporeal respiratory support before transplantation rose from 9% to 13%. The one-year survival rate after lung transplantation was 76% in 2009-2011 and 81% in 2012-2014.

CONCLUSION

The introduction of the LAS in Germany was associated with a decrease in the number of patients on the waiting list, and also in the number of deaths among patients on the waiting list. The distribution of primary diagnoses among transplant recipients shifted away from obstructive and toward restrictive lung diseases. In the future, additional parameters of patients on the waiting list should be considered to enable further improvement of the allocation model.

Effect of broader geographic sharing of donor lungs on lung transplant waitlist outcomes

BACKGROUND

The United States lung allocation system prioritizes allocation based on medical urgency and benefit but does not address a federal mandate for broader geographic organ sharing. It is unknown whether broader geographic sharing of donor lungs would improve lung transplant waitlist outcomes.

METHODS

A discrete event microsimulation model simulated donor lung allocation according to different geographic lung-sharing policies, including the historic local donor service area (DSA)-based policy and hypothetical policies that prioritize candidates to donors within 500-mile or 1,000-mile geographic radii. Candidate waitlist mortality, number of transplants, and 1-year survival were compared across organ allocation policies. Waitlist mortality rates were further stratified by diagnosis, Lung Allocation Score (LAS) threshold, ABO blood type, and region.

RESULTS

Under broader geographic lung sharing, the proportion of chronic obstructive pulmonary disease transplant recipients decreased, whereas the proportion of pulmonary fibrosis recipients increased. Waitlist mortality decreased with broader geographic lung sharing with a 21.3% decrease in waitlist mortality with 500-mile lung sharing and a 31.8% decrease in waitlist mortality with 1,000-mile lung sharing. The decrease in waitlist deaths occured across all U.S. geographic regions and was greatest in candidates with pulmonary fibrosis and/or high medical urgency.

CONCLUSIONS

Broader geographic sharing of donor lungs could reduce waitlist mortality, particularly among pulmonary fibrosis and high-medical-urgency candidates.

A mobile health technology enabled home-based intervention to treat frailty in adult lung transplant candidates: A pilot study

BACKGROUND

Frailty is prevalent in lung transplant candidates (LTC) and is associated with waitlist delisting or death. We performed a pilot study to assess the safety and feasibility of a home-based, mobile health technology-facilitated intervention to treat frailty in LTC.

METHODS

We performed an 8-week, nonrandomized, home-based exercise and nutrition intervention in LTC with Short Physical Performance Battery (SPPB) frailty scores of ≤11. The intervention utilized a customized, mobile device application ("app") enabling monitoring and progression of the intervention in real time. We aimed to evaluate key process measures. Secondarily, we tested whether the intervention could improve frailty scores quantified by the SPPB and Fried Frailty Phenotype (FFP).

RESULTS

A total of 15 subjects enrolled were 63 ± 5.7 years old; oxygen requirements ranged from 3 to 15LPM. Thirteen subjects completed the intervention. Over 108 subject-weeks, there were no adverse events. Subjects found the app engaging and easy to work with. SPPB frailty improved in 7 (54%) and FFP improved in 8 (62%). There was a strong trend toward improved frailty scores (SPPB change 1.0 ± 1.9; P = .08; FFP change -0.6 ± 1.0; P = .07).

CONCLUSION

In this pilot study, we found that a home-based prehabilitation program that leverages mobile health technology to target frailty in LTC is well received, safe, and capable of improving physical frailty scores.

Association of body mass index with lung transplantation survival in the United States following implementation of the lung allocation score

BACKGROUND

The association of body mass index (BMI) with survival after lung transplantation remains controversial, owing to conflicting evidence in the literature. Previous reports have used traditional BMI categories, included patients who underwent transplantation before implementation of the lung allocation score (LAS), or were limited by single-center experiences. Here we evaluated the association of individual BMI units with short-term and long-term mortality in a large national database following implementation of the LAS.

METHODS

The Scientific Registry of Transplant Recipients database was used to collect data for 17,233 adult lung transplantations performed between May 2005 and June 2016. The primary outcome was all-cause mortality at 90 days and 1 year posttransplantation. Logistic regression modeling was used to independently predict mortality per BMI unit, adjusting for donor and recipient factors.

RESULTS

BMI was an independent predictor of mortality at both 90 days and 1 year. At 90 days, a BMI of 25 was associated with the lowest predicted probability of death (0.053; 95% confidence interval [CI], 0.047-0.049), with increased odds of mortality at BMI ≤20 and ≥28. At 1 year, a BMI of 26 was associated with the lowest predicted probability of death (0.12; 95% CI, 0.11-0.13), with increased odds of mortality at BMI ≤24 and ≥28.

CONCLUSIONS

Each individual BMI unit has a quantifiable effect on posttransplantation survival, and the patterns of effect do not fit into the predefined BMI categories. The mortality risk associated with BMI should be considered by transplant centers when making listing decisions and by regulatory bodies for estimating expected outcomes.

Worldwide trends in heart and lung transplantation: Guarding the most precious gift ever

Transplantation is sadly a therapy to die for. The survival of a recipient with end-stage heart or lung disease requires the demise of a human being through brain death or cessation of circulation, with the noblest final act of offering one's organs to another. However, transplantation is constrained by severe hemodynamic, regulatory, inflammatory, and metabolic stresses in the donor, rendering the majority of offered organs unsuitable for transplantation. Coupled with our inability to acquire exact molecular and cellular information and missed opportunities for effectively modulating deteriorations of donors and allografts, anesthesia and critical care contributes to ongoing organ shortages. Progress is made with improving waiting lists by bridging patients for transplantation using mechanical support. However, this represents more complex recipients, higher risk transplant operations, and increased resource utilization. The advent of ex vivo perfusion allows implementing novel diagnostic and therapeutic strategies with real potential of reconditioning less ideal organs. This review advocates a paradigm change in critical care management of the potential donor for improving retrieval practices and for more intellectual involvement of our specialties in organ preservation, ex vivo evaluation and reconditioning, and the need for great advancement in our efficiency in converting unacceptable allografts to suitable donor organs.

Center Volume and Extracorporeal Membrane Oxygenation Support at Lung Transplantation in the Lung Allocation Score Era

RATIONALE

Outcomes related to extracorporeal membrane oxygenation (ECMO) used to bridge patients to lung transplantation in the context of center differences in transplant expertise have not been investigated.

OBJECTIVES

To determine the effects of ECMO at time of transplant on survival in adult patients who underwent transplant surgery in historically low- and high-volume centers.

METHODS

The United Network for Organ Sharing database was used to classify centers according to transplant volume between May 2005 and May 2010 as low-volume centers (bottom 50% of centers), medium-volume centers (next 25%), or high-volume centers (top 25%). Influences of ECMO on post-transplant survival were estimated among adults receiving lung transplants between June 2010 and June 2015 based on historic center volume in the preceding 5 years.

MEASUREMENTS AND MAIN RESULTS

Sixty-five centers were classified according to lung transplant volume in 2005-2010, with 8,228 adults (279 on ECMO) who underwent transplants at these centers between June 2010 and June 2015 included in the survival analysis. In multivariable Cox analysis stratified by center, we found that, in historically low-volume centers, ECMO was associated with increased post-transplant mortality hazard (hazard ratio, 1.968; 95% confidence interval, 1.083-3.577; P = 0.026). In contrast, in historically high-volume centers, ECMO had no adverse influence on post-transplant survival (hazard ratio, 0.853; 95% confidence interval, 0.596-1.222; P = 0.386).

CONCLUSIONS

An adverse effect of ECMO at the time of lung transplant was evident in low-volume centers but absent in centers with experience of performing more than 170 lung transplants in the first 5 years of the lung allocation score era.

Same policy, different impact: Center-level effects of share 35 liver allocation

Early studies of national data suggest that the Share 35 allocation policy increased liver transplants without compromising posttransplant outcomes. Changes in center-specific volumes and practice patterns in response to the national policy change are not well characterized. Understanding center-level responses to Share 35 is crucial for optimizing the policy and constructing effective future policy revisions. Data from the United Network for Organ Sharing were analyzed to compare center-level volumes of allocation-Model for End-Stage Liver Disease (aMELD) ≥ 35 transplants before and after policy implementation. There was significant center-level variation in the number and proportion of aMELD ≥ 35 transplants performed from the pre- to post-Share 35 period; 8 centers accounted for 33.7% of the total national increase in aMELD ≥ 35 transplants performed in the 2.5-year post-Share 35 period, whereas 25 centers accounted for 65.0% of the national increase. This trend correlated with increased listing at these centers of patients with Model for End-Stage Liver Disease (MELD) ≥ 35 at the time of initial listing. These centers did not overrepresent the total national volume of liver transplants. Comparison of post-Share 35 aMELD to calculated time-of-transplant (TOT) laboratory MELD scores showed that only 69.6% of patients transplanted with aMELD ≥ 35 maintained a calculated laboratory MELD ≥ 35 at the TOT. In conclusion, Share 35 increased transplantation of aMELD ≥ 35 recipients on a national level, but the policy asymmetrically impacted practice patterns and volumes of a subset of centers. Longer-term data are necessary to assess outcomes at centers with markedly increased volumes of high-MELD transplants after Share 35. Liver Transplantation 23 741-750 2017 AASLD.

Effect of Lung Transplantation on Health-Related Quality of Life in the Era of the Lung Allocation Score: A U.S. Prospective Cohort Study

Under the U.S. Lung Allocation Score (LAS) system, older and sicker patients are prioritized for lung transplantation (LT). The impact of these changes on health-related quality of life (HRQL) after transplant has not been determined. In a single-center prospective cohort study from 2010 to 2016, we assessed HRQL before and repeatedly after LT for up to 3 years using the SF12-Physical and Mental Health, the respiratory-specific Airway Questionnaire 20-Revised, and the Euroqol 5D/Visual Analog Scale utility measures by multivariate linear mixed models jointly modeled with death. We also tested changes in LT-Valued Life Activities disability, BMI, allograft function, and 6-min walk test exercise capacity as predictors of HRQL change. Among 211 initial participants (92% of those eligible), LT improved HRQL by all 5 measures (p < 0.05) and all but SF12-Mental Health improved by threefold or greater than the minimally clinically important difference. Compared to younger participants, those aged ≥65 improved less in SF12-Physical and Mental Health (p < 0.01). Improvements in disability accounted for much of the HRQL improvement. In the LAS era, LT affords meaningful and durable HRQL improvements, mediated by amelioration of disability. Identifying factors limiting HRQL improvement in selected subgroups, especially those aged ≥65, are needed to maximize the net benefits of LT.

Gender differences in long-term survival post-transplant: A single-institution analysis in the lung allocation score era

The purpose of this study was to clarify the significance of recipient gender status on lung transplant outcomes in a large single-institution experience spanning three decades, we analyzed data from all lung transplants performed in our institution since 1986. Kaplan-Meier curves and Cox proportional hazard models were used to evaluate the effect of recipient characteristics on survival and BOS score ≥1-free survival. Logistic regression analysis was used to explore the association of gender with short-term graft function. About 876 lung transplants were performed between 1986 and 2016. Kaplan-Meier survival estimates at 5 years post-transplant for females vs males in the LAS era were 71% vs 58%. In the LAS era, females showed greater unadjusted BOS≥1-free survival than males (35% vs 25%, P=.02) over 5 years. Female gender was the only factor in the LAS era significantly associated with improved adjusted 5-year survival [HR 0.56 (95% CI 0.33, 0.95) P=.03]. Conversely, in the pre-LAS era female gender was not associated with improved survival. Female recipients showed significantly improved survival over 5 years compared to males in the LAS era. A prospective analysis of biologic and immunologic differences is warranted.