Lung and heart allocation in the United States

Multiple listing in lung transplant candidates: A cohort study

Lung transplant candidates can be waitlisted at more than one transplant center, a practice known as multiple listing. The factors associated with multiple listing and whether multiple listing modifies waitlist mortality or likelihood of lung transplant is unknown. US lung transplant waitlist candidates were identified as either single or multiple listed using data from the Scientific Registry of Transplant Recipients. Characteristics of single and multiple listed candidates were compared and multivariable logistic regression was used to estimate associations with multiple listing. Multiple listed candidates were matched to single listed candidates using a combination of exact and propensity score matching methods. Cox proportional hazard models were used to estimate the relationship of multiple listing on waitlist mortality and receiving a transplant. Multiple listing occurred in 2.3% of lung transplant waitlist candidates. Younger age, female gender, white race, short stature, high antibody sensitization, college or postcollege education, lower lung allocation score, and a cystic fibrosis diagnosis were independently associated with multiple listing. Multiple listing was associated with an increased likelihood of lung transplant (adjusted hazard ratio [aHR] 2.74, 95% CI 2.37 to 3.16) but was not associated with waitlist mortality (aHR 0.99, 95% CI 0.68 to 1.44).

Patient outcomes from time of listing for lung transplantation in the UK: are there disease-specific differences?

Background

The demand for lung transplantation vastly exceeds the availability of donor organs. This translates into long waiting times and high waiting list mortality. We set out to examine factors influencing patient outcomes from the time of listing for lung transplantation in the UK, examining for differences by patient characteristics, lung disease category and transplant centre.

Methods

Data were obtained from the UK Transplant Registry held by NHS Blood and Transplant for adult lung-only registrations between 1January 2004 and 31 March 2014. Pretransplant and post-transplant outcomes were evaluated against lung disease category, blood group and height.

Results

Of the 2213 patient registrations, COPD comprised 28.4%, pulmonary fibrosis (PF) 26.2%, cystic fibrosis (CF) 25.4% and other lung pathologies 20.1%. The chance of transplantation after listing differed by the combined effect of disease category and centre (p<0.001). At 3 years postregistration, 78% of patients with COPD were transplanted followed by 61% of patients with CF, 59% of other lung pathology patients and 48% of patients with PF, who also had the highest waiting list mortality (37%). The chance of transplantation also differed by height with taller patients having a greater chance of transplant (HR: 1.03, 95% CI: 1.02 to 1.04, p<0.001). Patients with blood group O had the highest waiting mortality at 3 years postregistration compared with all other blood groups (27% vs 20%, p<0.001).

Conclusions

The way donor lungs were allocated in the UK resulted in discrepancies between the risk profile and probability of lung transplantation. A new donor lung allocation scheme was introduced in 2017 to try to address these shortcomings.

Heart-lung transplantation: current indications, prognosis and specific considerations

Heart-lung transplantation (HLTx) is currently the best treatment for patients who have end-stage heart and lung failure. Idiopathic pulmonary arterial hypertension (IPAH) was the main indication for HLTx in the 1980s. However, when studies showed resolution of right ventricular dysfunction after double-lung transplantation (DLTx), this last procedure became the preferred option for end-stage IPAH. Currently, the main indication of HLTx is congenital heart disease (CHD), followed by acquired heart disease combined with pulmonary hypertension and/or intrinsic lung disease. Although early posttransplant survival remains lower after HLTx than after lung transplantation, careful patient selection combined with surgical advances are producing improvements. Here, we review the practice patterns, trends, and outcomes of HLTx worldwide.

Implications of blood group on lung transplantation rates: A propensity-matched registry analysis

BACKGROUND

Blood type O lung allografts may be allocated to blood type identical (type O) or compatible (non-O) candidates. We tested the hypothesis that the current organ allocation schema in the United States-based on the Lung Allocation Score-prejudices against the allocation of allografts to type O candidates, given that the pool of potential donors is smaller.

METHODS

We performed a retrospective cohort review of the Organ Procurement and Transplantation Network/United Network of Organ Sharing registry from May 2005 to March 2017 for adult candidates on the waiting list for first-time isolated lung transplantation. Demographic data were compiled and described, and 1:1 nearest-neighbor propensity score matching was used to adjust for age and Lung Allocation Score at listing.

RESULTS

A total of 26,396 candidates met inclusion criteria: 14,329 type non-O and candidates and 12,068 type O candidates. After matching, 11,951 candidates were included in each group. Of these, 77.0% of type non-O underwent lung transplantation vs 73.1% type O (p < 0.001). At 1 year, the waiting list mortality was higher for type O candidates (12.5%) than for non-O candidates (10.1%, p < 0.001). Of those undergoing transplantation, 5-year survival rates were similar.

CONCLUSIONS

Type O candidates experience lower rates of transplantation and higher rates of waiting list mortality compared with matched type non-O candidates. Further evaluation of regional sharing of allografts to increase transplantation rates for type O candidates may be warranted to optimize equity in access to transplants.

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.

Estimating the causal effect of treatment regimes for organ transplantation

Patients awaiting cadaveric organ transplantation face a difficult decision if offered a low-quality organ: accept the organ or remain on the waiting list and hope a better organ is offered in the future. A dynamic treatment regime (DTR) for transplantation is a rule that determines whether a patient should decline an offered organ. Existing methods can estimate the effect of DTRs on survival outcomes, but these were developed for applications where treatment is abundantly available. For transplantation, organ availability is limited, and existing methods can only estimate the effect of a DTR assuming a single patient follows the DTR. We show for transplantation that the effect of a DTR depends on whether other patients follow the DTR. To estimate the anticipated survival if the entire population awaiting transplantation were to adopt a DTR, we develop a novel inverse probability weighted estimator (IPCW) which re-weights patients based on the probability of following their transplant history in the counterfactual world in which all patients follow the DTR of interest. We estimate this counterfactual probability using hot deck imputation to fill in data that is not observed for patients who are artificially censored by IPCW once they no longer follow the DTR of interest. We show via simulation that our proposed method has good finite-sample properties, and we apply our method to a lung transplantation observational registry.

Geographic disparities in donor lung supply and lung transplant waitlist outcomes: A cohort study

Despite the Final Rule mandate for equitable organ allocation in the United States, geographic disparities exist in donor lung allocation, with the majority of donor lungs being allocated locally to lower-priority candidates. We conducted a retrospective cohort study of 19 622 lung transplant candidates waitlisted between 2006 and 2015. We used multivariable adjusted competing risk survival models to examine the relationship between local lung availability and waitlist outcomes. The primary outcome was a composite of death and removal from the waitlist for clinical deterioration. Waitlist candidates in the lowest quartile of local lung availability had an 84% increased risk of death or removal compared with candidates in the highest (subdistribution hazard ratio [SHR]: 1.84, 95% confidence interval [CI]: 1.51-2.24, P < .001). The transplantation rate was 57% lower in the lowest quartile compared with the highest (SHR: 0.43, 95% CI: 0.39-0.47). The adjusted death or removal rate decreased by 11% with a 50% increase in local lung availability (SHR: 0.89, 95% CI: 0.85-0.93, P < .001) and the adjusted transplantation rate increased by 19% (SHR: 1.19, 95% CI: 1.17-1.22, P < .001). There are geographically disparate waitlist outcomes in the current lung allocation system. Candidates listed in areas of low local lung availability have worse waitlist outcomes.

State of the Art in Pediatric Lung Transplantation

Pediatric lung transplantation is a highly specialized therapy for end-stage pulmonary disease in children, and is performed in only a handful of transplant centers around the world. Advancement in the field has been made on many fronts in recent years, including in public policy and organ allocation strategies, donor selection and management, emerging technologies for donor lung rehabilitation and bridge-to-transplant support of listed candidates, and ongoing refinement of surgical techniques. Despite this progress, children continue to suffer discrepant waitlist mortality and longer waiting times than their adult counterparts, and face special challenges of donor availability and size matching. Here, we assess the current state of the art in pediatric lung transplantation, reviewing progress made to date and further opportunities to improve care for this unique group of patients.

The Past, Present and Future of Heart Transplantation

Heart transplantation (HTx) has become standard treatment for selected patients with end-stage heart failure. Improvements in immunosuppressant, donor procurement, surgical techniques, and post-HTx care have resulted in a substantial decrease in acute allograft rejection, which had previously significantly limited survival of HTx recipients. However, limitations to long-term allograft survival exist, including rejection, infection, coronary allograft vasculopathy, and malignancy. Careful balance of immunosuppressive therapy and vigilant surveillance for complications can further improve long-term outcomes of HTx recipients.

Overview of Lung Transplantation, Heart-Lung Transplantation, Liver-Lung Transplantation, and Combined Hematopoietic Stem Cell Transplantation and Lung Transplantation

Lung transplantation (LTx) has evolved to represent the therapy of choice for many patients with end-stage lung diseases. Appropriate candidate selection for LTx is an important determinant of a positive outcome from transplantation. Posttransplantation survival has steadily improved, but long-term survival continues to be a challenge with a median survival of 5.8 years. Similarly, combined heart-lung transplantation and simultaneous liver-lung transplantation has been performed successfully in select patients who are not expected to survive either organ transplant alone. Moreover, LTx has been performed in patients who develop end-stage pulmonary complications following hematopoietic stem cell transplantation.

Contemporary Issues in Lung Transplant Allocation Practices

PURPOSE OF REVIEW

To discuss the current state of donor lung allocation in the United States, and future opportunities to increase the efficiency of donor lung allocation.

RECENT FINDINGS

The current donor lung allocation system prioritizes clinical acuity by use of the Lung Allocation Score (LAS) which has reduced waitlist mortality since its implementation in 2005. Access to donor lungs can be further improved through policy changes using broader geographic sharing, and developing new technology such as ex vivo lung perfusion to recover marginal donor lungs.

SUMMARY

The number of lung transplants in the U.S. continues to increase annually. However, the demand for donor lungs continues to be outpaced by an ever growing waitlist. Efficient allocation can be achieved through improved allocation policies and new technology.

Efficient and Fair Heart Allocation Policies for Transplantation

Background: The optimal allocation of limited donated hearts to patients on the waiting list is one of the top priorities in heart transplantation management. We developed a simulation model of the US waiting list for heart transplantation to investigate the potential impacts of allocation policies on several outcomes such as pre- and posttransplant mortality. Methods: We used data from the United Network for Organ Sharing (UNOS) and the Scientific Registry of Transplant Recipient (SRTR) to simulate the heart allocation system. The model is validated by comparing the outcomes of the simulation with historical data. We also adapted fairness schemes studied in welfare economics to provide a framework to assess the fairness of allocation policies for transplantation. We considered three allocation policies, each a modification to the current UNOS allocation policy, and analyzed their performance via simulation. The first policy broadens the geographical allocation zones, the second modifies the health status order for receiving hearts, and the third prioritizes patients according to their waiting time. Results: Our results showed that the allocation policy similar to the current UNOS practice except that it aggregates the three immediate geographical allocation zones, improves the health outcomes, and is “closer” to an optimal fair policy compared to all other policies considered in this study. Specifically, this policy could have saved 319 total deaths (out of 3738 deaths) during the 2006 to 2014 time horizon, in average. This policy slightly differs from the current UNOS allocation policy and allows for easy implementation. Conclusion: We developed a model to compare the outcomes of heart allocation policies. Combining the three immediate geographical zones in the current allocation algorithm could potentially reduce mortality rate and is closer to an optimal fair policy.

Regional variation in the use of 1A status exceptions for pediatric heart transplant candidates: is this equitable?

The use of status exceptions (SE) was recently publicized as a strategy to reduce waitlist times for children awaiting heart transplant (HTx). The aim of this study was to assess SE use across UNOS regions and compare survival in patients listed using a SE to those listed by standard criteria. The OPTN database was queried for all pediatric patients listed for HTx (2000-2014). SE use was compared across UNOS regions. Survival curves were generated and compared using the log-rank test. 1A SE use is uncommon, being utilized in 108 of 4587 pediatric 1A listings (2.4%). There is significant variability in SE use across UNOS regions (0.7%-16.4% of 1A listings, P < .001). Waitlist survival is significantly higher in candidates listed using a 1A SE compared to those listed by standard criteria (P = .001) and is similar to 1B listings. Regional variation in 1A SE use has the potential to introduce bias into a system designed to be equitable. Waitlist survival in patients listed using a SE is similar to those listed status 1B, suggesting these patients may not require 1A status. Careful review of pediatric heart allocation policies is needed to optimize patient outcomes and ensure a fair and unbiased allocation system.

Improved waitlist and transplant outcomes for pediatric lung transplantation after implementation of the lung allocation score

BACKGROUND

Although the lung allocation score (LAS) has not been considered valid for lung allocation to children, several additional policy changes for pediatric lung allocation have been adopted since its implementation. We compared changes in waitlist and transplant outcomes for pediatric and adult lung transplant candidates since LAS implementation.

METHODS

The United Network for Organ Sharing database was reviewed for all lung transplant listings during the period 1995 to June 2014. Outcomes were analyzed based on date of listing (pre-LAS vs post-LAS) and candidate age at listing (adults >18 years, adolescents 12 to 17 years, children 0 to 11 years).

RESULTS

Of the 39,962 total listings, 2,096 (5%) were for pediatric candidates. Median waiting time decreased after LAS implementation for all age groups (adults: 379 vs 83 days; adolescents: 414 vs 104 days; children: 211 vs 109 days; p < 0.001). The proportion of candidates reaching transplant increased after LAS (adults: 52.6% vs 71.6%, p < 0.001; adolescents: 40.3% vs 61.6%, p < 0.001; children: 42.4% vs 50.9%, p = 0.014), whereas deaths on the waitlist decreased (adults: 28.0% vs 14.4%, p < 0.001; adolescents: 33.1% vs 20.9%, p < 0.001; children: 32.2% vs 25.0%; p = 0.025), despite more critically ill candidates in all groups. Median recipient survival increased after LAS for adults and children (adults: 5.1 vs 5.5 years, p < 0.001; children: 6.5 vs 7.6 years, p = 0.047), but not for adolescents (3.6 vs 4.3 years, p = 0.295).

CONCLUSIONS

Improvements in waiting time, mortality and post-transplant survival have occurred in children after LAS implementation. Continued refinement of urgency-based allocation to children and broader sharing of pediatric donor lungs may help to maximize these benefits.

Extracorporeal membrane oxygenation support and post-heart transplant outcomes among United States adults

BACKGROUND

Patients supported with extracorporeal membrane oxygenation (ECMO) are given priority listing status for heart transplant (HT). Data on post-HT outcomes for adults with ECMO support at the time of HT are limited.

METHODS

We analyzed data from the United Network for Organ Registry (UNOS) registry for 157 ECMO-supported adults (age ≥ 18 years) undergoing HT after January 1, 2000. Data at the time of HT were examined for their association with post-transplant mortality using multivariable Cox proportional hazard analyses.

RESULTS

Patients (69.4% males; mean age, 46.0 ± 15.6 years; 15.9% African Americans) were monitored for median of 0.55 years (interquartile range, 0.04-4.5). Seventy patients (44.6%) died during follow-up (survival at 1 year was 57.8%), of which 43 (61.4%) died within 30 days post-HT. For patients surviving the first 30 days after transplant, long-term survival was acceptable (82.3% at 1 year and 76.2% at 5 years). Prevalence of immediate post-HT complications, such as stroke and need for dialysis, were 10.1% and 28.1%, respectively. Post-HT survival did not differ between those who received an allograft before and after January 1, 2009 (univariate hazard ratio, 0.84; 95% confidence interval, 0.51-1.38; p = 0.48). Among the predictors identified for 30-day and long-term mortality were recipient history of renal insufficiency (RI; defined as estimated glomerular filtration rate < 45 ml/min/1.73 m² or dialysis) and mechanical ventilation (MV; interaction p < 0.05); those with both MV and RI had significantly poorer post-transplant survival (29.4% and 12.5% for 30-day and 1-year survival, respectively) compared with those without (78.7% and 71.4% for 30-day and 1-year survival, respectively).

CONCLUSIONS

Post-HT mortality did not change for ECMO-supported adults in the contemporary era, and those with RI and MV had significantly poorer post-transplant survival. A critical review of priority listing status for ECMO-supported patients is warranted for optimal allocation and outcomes of cardiac allografts.

Overcoming Challenges

Lung donation and transplantation is increasing in volume annually, yet there continues to be a shortage of available organs for transplant. Despite this shortage, suitable lungs are occasionally not transplanted due to logistical issues. Issues such as time and distance can be a major barrier in deceased donor organ recovery and transplantation. This single case study serves as an example of the teamwork and cooperation that resulted in the successful transplantation of lungs in spite of long-distance logistical issues between the donor and the recipient. All of the members who contributed to this collaboration recognized the need and urgency to overcome these challenges. The organ procurement organization’s collaboration with multiple transplant centers across multiple regions resulted in a successful outcome for the lung recipient.

Successful transplantation in canines after long-term coronary sinus machine perfusion preservation of donor hearts

BACKGROUND

Machine perfusion is a promising strategy for donor heart preservation, but delivery of perfusate through the aorta may be limited by aortic valve incompetence. We hypothesized that retrograde machine perfusion preservation through the coronary sinus avoided this issue and allowed for recovery of donor hearts after long-term storage.

METHODS

Canine hearts were procured after arrest with 1 liter University of Wisconsin Machine Perfusion Solution (UWMPS) and preserved for 14 hours by static hypothermic storage (Static group, n = 5) or retrograde machine perfusion through the coronary sinus (RP group, n = 5). Myocardial oxygen consumption (MVo2) and lactate were monitored in perfused hearts. Hearts were implanted and reperfused for 6 hours. The pre-load recruitable stroke work was determined as a measure of myocardial function. Cardiac enzyme release was quantified. Cell death was evaluated by TUNEL (terminal deoxynucleotidyltransferase-mediated deoxy uridine triphosphate nick-end label).

RESULTS

MVo2 decreased initially then stabilized. Lactate accumulation was low in RP hearts. All RP hearts separated from cardiopulmonary bypass. All Static hearts required a return to bypass (p < .05). Pre-load recruitable stroke work in RP hearts was increased (55 ± 7 mm Hg) compared with Static (20 ± 11 mm Hg, p < .05) and did not differ from baseline values. Creatine kinase release was greater in Static group hearts (102 ± 16 IU/liter/g) than in RP hearts (51 ± 8 IU/liter/g, p < .05). The fraction of TUNEL-positive cells was higher in the Static group, but this difference was not significant.

CONCLUSIONS

Retrograde machine perfusion can preserve donor hearts for long intervals. Cardiac function after implantation suggested excellent myocardial protection. Retrograde machine perfusion appears promising for extending the donor ischemic interval and improving results of heart transplantation.

Broader Geographic Sharing of Pediatric Donor Lungs Improves Pediatric Access to Transplant

US pediatric transplant candidates have limited access to lung transplant due to the small number of donors within current geographic boundaries, leading to assertions that the current lung allocation system does not adequately serve pediatric patients. We hypothesized that broader geographic sharing of pediatric (adolescent, 12-17 years; child, <12 years) donor lungs would increase pediatric candidate access to transplant. We used the thoracic simulated allocation model to simulate broader geographic sharing. Simulation 1 used current allocation rules. Simulation 2 offered adolescent donor lungs across a wider geographic area to adolescents. Simulation 3 offered child donor lungs across a wider geographic area to adolescents. Simulation 4 combined simulations 2 and 3. Simulation 5 prioritized adolescent donor lungs to children across a wider geographic area. Simulation 4 resulted in 461 adolescent transplants per 100 patient-years on the waiting list (range 417-542), compared with 206 (range 180-228) under current rules. Simulation 5 resulted in 388 adolescent transplants per 100 patient-years on the waiting list (range 348-418) and likely increased transplant rates for children. Adult transplant rates, waitlist mortality, and 1-year posttransplant mortality were not adversely affected. Broader geographic sharing of pediatric donor lungs may increase pediatric candidate access to lung transplant.

Lung Transplantation

The therapeutic options for patients with advanced pulmonary parenchymal or vascular disorders are currently limited. Lung transplantation remains one of the few viable interventions, but on account of the insufficient donor pool only a minority of these patients actually undergo the procedure each year. Following transplantation there are a number of early and late allograft complications such as primary graft dysfunction, allograft rejection, infection, post-transplant lymphoproliferative disorder and late injury that is now classified as chronic lung allograft dysfunction. The pathologist plays an essential role in the diagnosis and classification of these myriad complications. Although the transplant procedures are performed in selected centers patients typically return to their local centers. When complications arise it is often the responsibility of the local pathologist to evaluate specimens. Therefore familiarity with the pathology of lung transplantation is important.

Gerrymandering for Justice: Redistricting U.S. Liver Allocation

U.S. organ allocation policy sequesters livers from deceased donors within arbitrary geographic boundaries, frustrating the intent of those who wish to offer the livers to transplant candidates based on medical urgency. We used a zero-one integer program to partition 58 donor service areas into between four and eight sharing districts that minimize the disparity in liver availability among districts. Because the integer program necessarily suppressed clinically significant differences among patients and organs, we tested the optimized district maps with a discrete-event simulation tool that represents liver allocation at a per-person, per-organ level of detail. In April 2014, the liver committee of the Organ Procurement and Transplantation Network (OPTN) decided in a unanimous vote of 22-0-0 to write a policy proposal based on our eight-district and four-district maps. The OPTN board of directors could implement the policy after the proposal and public-comment period.Redistricting liver allocation would save hundreds of lives over the next five years and would attenuate the serious geographic inequity in liver transplant offers.

Increasing the Number of Organ Transplants in the United States by Optimizing Donor Authorization Rates

While recent policies have focused on allocating organs to patients most in need and lessening geographic disparities, the only mechanism to increase the actual number of transplants is to maximize the potential organ supply. We conducted a retrospective cohort study using OPTN data on all "eligible deaths" from 1/1/08 to 11/1/13 to evaluate variability in donor service area (DSA)-level donor authorization rates, and to quantify the potential gains associated with increasing authorization rates. Despite adjustments for donor demographics (age, race/ethnicity, cause of death) and geographic factors (rural/urban status of donor hospital, statewide participation in deceased-donor registries) among 52 571 eligible deaths, there was significant variability (p < 0.001) in donor authorization rates across the 58 DSAs. Overall DSA-level adjusted authorization rates ranged from 63.5% to 89.5% (median: 72.7%). An additional 773-1623 eligible deaths could have been authorized, yielding 2679-5710 total organs, if the DSAs with authorization rates below the median and 75th percentile, respectively, implemented interventions to perform at the level of the corresponding reference DSA. Opportunities exist within the current organ acquisition framework to markedly improve DSA-level donor authorization rates. Such initiatives would mitigate waitlist mortality while increasing the number of transplants.

Heart and lung transplantation

PURPOSE OF REVIEW

Every year, thousands of heart and lung transplants are performed worldwide. As experience and clinical acumen advance, both fields are continually evolving. This review elucidates and describes many of the recent changes in practice and future directions of heart and lung transplantation. Preoperative, intraoperative and postoperative developments are presented with supporting evidence in these continually evolving fields.

RECENT FINDINGS

The field of heart transplantation is continually adapting to the growing use of mechanical circulatory support devices as bridge to transplant and for postoperative support. Recent modifications in surgical technique have contributed to improved outcomes.Lung transplantation advancements include the increasing use of extracorporeal membrane oxygenation during the perioperative period. Lobar transplantation and ex-vivo lung perfusion techniques may aid in providing successful lung grafts to those with potentially long wait list times.Rates of rejection continue to decline in both fields as immunosuppression regimens are improved and modified.

SUMMARY

This review investigates and summarizes the recent changes and advancements in heart and lung transplantation. Mechanical circulatory support and extracorporeal membrane oxygenation are increasingly used in the perioperative setting, and continuing research will evaluate their safety profiles. Optimizing and tailoring immunosuppression regimens for transplant recipients continue to be the subject of ongoing investigation.

Lung transplantation with lungs from older donors: recipient and surgical factors affect outcomes

BACKGROUND

A shortage of donors has compelled the use of extended-criteria donor organs in lung transplantation. The purpose of this study was to evaluate the impact of using older donors on outcomes after lung transplantation using current protocols.

METHODS

From January 2003 to August 2009, 593 lung transplants were performed at our institution. We compared 87 patients (14.7%) who received lungs from donors aged 55 years or older with 506 patients who received lungs from donors less than 55 years old. We also examined risk factors for mortality in recipients of lungs from older donors.

RESULTS

The incidence of major complications including severe primary graft dysfunction and early mortality rates were similar between the groups. However, posttransplant peak FEV1 was lower in the patients who received lungs from older donors (71.7% vs. 80.7%, P<0.05). In multivariate analysis, recipient pulmonary hypertension (transpulmonary pressure gradient >20 mm Hg) and prolonged intraoperative cardiopulmonary bypass were significant risk factors for mortality in the recipients of lungs from older donors.

CONCLUSIONS

This large, single-center experience demonstrated that transplanting lungs from donors older than 55 years did not yield worse short- or long-term outcomes as compared with transplanting lungs from younger donors. However, transplanting lungs from older donors into recipients with pulmonary hypertension or recipients who required prolonged cardiopulmonary bypass increased the risk for mortality. Although lungs from older donors should not be excluded because of donor age alone, surgeons should carefully consider their patient selection criteria and surgical plans when transplanting lungs from older donors.

Advanced therapies for COPD-What's on the horizon? Progress in lung volume reduction and lung transplantation

Advanced chronic obstructive pulmonary disease (COPD) is a significant cause of morbidity. Treatment options beyond conventional medical therapies are limited to a minority of patients. Lung volume reduction surgery (LVRS) although effective in selected subgroups of patients is not commonly undertaken. Morbidity associated with the procedure has contributed to this low utilisation. In response to this, less invasive bronchoscopic lung volume techniques are being developed to attempt to mitigate some of the risks and costs associated with surgery. Of these, endobronchial valve therapy is the most comprehensively studied although the presence of collateral ventilation in a significant proportion of patients has compromised its widespread utility. Bronchial thermal vapour ablation and lung volume reduction (LVR) coils are not dependent on collateral ventilation. These techniques have shown promise in early clinical trials; ongoing work will establish whether they have a role in the management of advanced COPD. Lung transplantation, although effective in selected patients for palliation of symptoms and improving survival, is limited by donor organ availability and economic constraint. Reconditioning marginal organs previously declined for transplantation with ex vivo lung perfusion (EVLP) is one potential strategy in improving the utilisation of donor organs. By increasing the donor pool, it is hoped lung transplantation might be more accessible for patients with advanced COPD into the future.

Reframing the impact of combined heart-liver allocation on liver transplant wait-list candidates

Simultaneous heart-liver (H-L) transplantation, although rare, has become more common in the United States. When the primary organ is a heart or liver, patients receiving an offer for the primary organ automatically receive the second, nonprimary organ from that donor. This policy raises issues of equity, such as whether liver transplantation alone candidates bypassed by H-L recipients are disadvantaged. No prior published analyses have addressed this issue, and few methods have been developed as means of measuring the impact of such allocation policies. We analyzed Organ Procurement and Transplantation Network match run data from 2007 to 2013 to determine whether this combined organ allocation policy disadvantages bypassed liver transplant wait-list candidates in a clinically meaningful way. Among 65 H-L recipients since May 2007, 42 had substantially higher priority for the heart versus the liver, and these 42 bypassed 268 liver-alone candidates ranked 1 to 10 on these match runs. Bypassed patients had a lower risk of wait-list removal for death or clinical deterioration in comparison with controls selected by the match Model for End-Stage Liver Disease (MELD) score [hazard ratio (HR) = 0.56, 95% confidence interval (CI) = 0.40-0.79] and a risk similar to that of controls selected by the laboratory MELD score (HR = 0.91, 95% CI = 0.63-1.33) or on match runs of similar graft quality (HR = 0.97, 95% CI = 0.73-1.37). The waiting time from bypass to subsequent transplantation was significantly longer among bypassed candidates versus controls on match runs of similar graft quality [median: 87 days (interquartile range = 27-192 days) versus 24 days (interquartile range = 5-79 days), P < 0.001]. Although transplantation was delayed, liver transplant wait-list candidates bypassed by H-L recipients did not have excess mortality in comparison with 3 sets of matched controls. These analytic methods serve as a starting point for considering other potential approaches to evaluating the impact of multiorgan transplant allocation policies.

Does the UNOS heart transplant allocation system favor men over women?

OBJECTIVES

The aim of this paper was to identify sex differences in survival of patients awaiting orthotopic heart transplantation (OHT).

BACKGROUND

Women have a higher mortality rate while awaiting OHT than men, and the reason has not been fully determined.

METHODS

We included all adult patients in the Scientific Registry of Transplant Recipients (SRTR) placed on the OHT waiting list from 2000 to 2010. The primary endpoint was all-cause mortality before receiving OHT, analyzed using time-to-event analysis. Multivariate Cox proportional hazards models were used to evaluate sex differences in survival, with data stratified by United Network for Organ Sharing (UNOS) status at time of listing.

RESULTS

There were 28,852 patients (24% women) awaiting OHT. This cohort included 6,163 UNOS status 1A (25% women), 9,168 UNOS status 1B (25% women), and 13,521 UNOS status 2 (24% women) patients. During a median follow-up of 3.7 years, 1,290 women and 4,286 men died. Female sex was associated with a significant risk of death among UNOS status 1A (adjusted hazard ratio [HR]: 1.20; 95% confidence interval [CI]: 1.05 to 1.37, p = 0.01) after adjusting for more than 30 baseline variables. In contrast, female sex was significantly protective for time to death among UNOS status 2 patients (adjusted HR: 0.75; 95% CI: 0.67 to 0.84, p < 0.001). No sex differences were noted among UNOS status 1B patients.

CONCLUSIONS

There are sex differences in survival between women and men awaiting heart transplantation, and the current UNOS transplant criteria do not account for this disparity.

Comparative Survival and Cost-Effectiveness of Advanced Therapies for End-Stage Heart Failure

Background—

Treatment options for end-stage heart failure include inotrope-dependent medical therapy, orthotopic heart transplantation (OHT), left ventricular assist device (LVAD) as destination therapy or bridge to transplant.

Methods and Results—

We developed a state-transition model to simulate 4 treatment options and associated morbidity and mortality. Transition probabilities, costs, and utilities were estimated from published sources. Calculated outcomes included survival, quality-adjusted life-years, and incremental cost-effectiveness. Sensitivity analyses were performed on model parameters to test robustness. Average life expectancy for OHT-eligible patients is estimated at 1.1 years, with 39% surviving to 1 year. OHT with a median wait time of 5.6 months is estimated to increase life expectancy to 8.5 years, and costs <$100 000/quality-adjusted life-year gained, relative to inotrope-dependent medical therapy. Bridge to transplant-LVAD followed by OHT further is estimated to increase life expectancy to 12.3 years, for $226 000/quality-adjusted life-year gained versus OHT. Among OHT-ineligible patients, mean life expectancy with inotrope-dependent medical therapy is estimated at 9.4 months, with 26% surviving to 1 year. Patients who instead received destination therapy-LVAD are estimated to live 4.4 years on average from extrapolation of recent constant hazard rates beyond the first year. This strategy costs $202 000/quality-adjusted life-year gained, relative to inotrope-dependent medical therapy. Patient’s age, time on wait list, and costs associated with care influence outcomes.

Conclusions—

Under most scenarios, OHT prolongs life and is cost effective in eligible patients. Bridge to transplant-LVAD is estimated to offer >3.8 additional life-years for patients waiting ≥6 months, but does not meet conventional cost-effectiveness thresholds. Destination therapy-LVAD significantly improves life expectancy in OHT-ineligible patients. However, further reductions in adverse events or improved quality of life are needed for destination therapy-LVAD to be cost effective.

Overview of clinical lung transplantation

Since the first successful lung transplant 30 years ago, lung transplantation has rapidly become an established standard of care to treat end-stage lung disease in selected patients. Advances in lung preservation, surgical technique, and immunosuppression regimens have resulted in the routine performance of lung transplantation around the world for an increasing number of patients, with wider indications. Despite this, donor shortages and chronic lung allograft dysfunction continue to prevent lung transplantation from reaching its full potential. With research into the underlying mechanisms of acute and chronic lung graft dysfunction and advances in personalized diagnostic and therapeutic approaches to both the donor lung and the lung transplant recipient, there is increasing confidence that we will improve short- and long-term outcomes in the near future.

The equitable allocation of deceased donor lungs for transplant in children in the United States

On June 5, 2013, a US Federal Court ordered a temporary restraining order to allow two children within the court's jurisdiction to be registered on the adolescent lung transplant waiting list. On June 10, 2013, the Organ Procurement and Transplantation Network's Executive Committee altered lung allocation policy to offer candidates aged younger than 12 years greater access to adult lungs at the discretion of the national Lung Review Board. The Scientific Registry of Transplant Recipients reviewed trends over time in deceased donor lung transplant waitlist mortality and transplant rates, comparing children and adults. Mortality rates of candidates active on the waiting list have been higher for children aged 0-5 years, but have not differed for children aged 6-11 years compared with adolescents aged 12-17 years or adults aged 18 years or older. Transplant rates among active waitlist candidates have been comparable across all age groups. Thus, there is little evidence that the allocation system led to differences in waitlist mortality or transplant rates for children compared with adults. However, these comparisons are difficult to interpret given that current policies likely led to unaccounted differences in the severity of illness at the time of listing.

Kidney, pancreas and liver allocation and distribution in the United States

Kidney transplant and liver transplant are the treatments of choice for patients with end-stage renal disease and end-stage liver disease, respectively. Pancreas transplant is most commonly performed along with kidney transplant in diabetic end-stage renal disease patients. Despite a steady increase in the numbers of kidney and liver transplants performed each year in the United States, a significant shortage of kidneys and livers available for transplant remains. Organ allocation is the process the Organ Procurement and Transplantation Network (OPTN) uses to determine which candidates are offered which deceased donor organs. OPTN is charged with ensuring the effectiveness, efficiency and equity of organ sharing in the national system of organ allocation. The policy has changed incrementally over time in efforts to optimize allocation to meet these often competing goals. This review describes the history, current status and future direction of policies regarding the allocation of abdominal organs for transplant, namely the kidney, liver and pancreas, in the United States.