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

Extracorporeal membrane oxygenation as a bridge to lung transplantation: Practice patterns and patient outcomes

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is increasingly relied on to bridge patients with respiratory failure to lung transplantation despite limited evidence for its use in this setting. This study evaluated longitudinal trends in practice patterns, patient characteristics, and outcomes in patients bridged with ECMO to lung transplant.

METHODS

A retrospective review of all adult isolated lung transplant patients in the United Network for Organ Sharing database between 2000 and 2019 was performed. Patients were classified as "ECMO" if supported with ECMO at the time of listing or transplantation and "non-ECMO" otherwise. Linear regression was used to evaluate trends in patient demographics during the study period. Trends in mortality were evaluated using Cox proportional hazards modeling, with time period as the primary covariate (2000-2004, 2005-2009, 2010-2014, or 2015-2019) and age, time on the waitlist, and underlying diagnosis as covariates.

RESULTS

The number of patients included were 40,866, of whom 1,387 (3.4%) were classified as ECMO and 39,479 (96.6%) as no ECMO. Average age and initial Lung Allocation Score increased significantly during the study period in both cohorts, but occurred at a slower rate in the ECMO population. The hazard of death was significantly lower in more recent years (2015-2019) for both the ECMO and non-ECMO cohorts (aHR (adjusted hazards ratio) 0.59, 95% confidence interval (CI) 0.37-0.96 and aHR 0.74, 95% CI 0.70-0.79) when compared to the early years (2000-2004) of the study period.

CONCLUSIONS

Post-transplantation survival for patients bridged to transplantation with ECMO demonstrates ongoing improvement despite cannulation of progressively older and sicker patients.

Expanding Donor Options for Lung Transplant: Extended Criteria, Donation After Circulatory Death, ABO Incompatibility, and Evolution of Ex Vivo Lung Perfusion

Only using brain-dead donors with standard criteria, the existing donor shortage has never improved in lung transplantation. Currently, clinical efforts have sought the means to use cohorts of untapped donors, such as extended criteria donors, donation after circulatory death, and donors that are ABO blood group incompatible, and establish the evidence for their potential contribution to the lung transplant needs. Also, technical maturation for using those lungs may eliminate immediate concerns about the early posttransplant course, such as primary graft dysfunction or hyperacute rejection. In addition, recent clinical and preclinical advances in ex vivo lung perfusion techniques have allowed the safer use of lungs from high-risk donors and graft modification to match grafts to recipients and may improve posttransplant outcomes. This review summarizes recent trends and accomplishments and future applications for expanding the donor pool in lung transplantation.

Lung transplant waitlist outcomes among ABO blood groups vary based on disease severity

BACKGROUND

Blood group O candidates have lower lung transplantation rates despite having the most common blood group. We postulated that waitlist outcomes among these candidates and those with other blood types vary with disease severity and lung allocation score (LAS).

METHODS

We performed a retrospective cohort study of 32,772 waitlist candidates using the United Network of Organ Sharing registry from May 2005 to 2020. After identifying an interaction between blood group and LAS, we evaluated the association between blood group and waitlist outcomes within LAS quartiles using unadjusted and adjusted competing risk models.

RESULTS

In the lowest LAS quartile, blood group O had a 20% reduced transplantation rate (SHR: 0.80, 95%CI: 0.75-0.85) and higher waitlist death/removal (1.33, 95%CI: 1.15-1.55) compared with group A. Blood group AB had a 52% higher transplantation rate (SHR: 1.52, 95%CI: 1.34-1.73) in the lowest LAS quartile compared with group A. In the highest LAS quartile, there was no difference in transplantation rates between groups O and A. In contrast, group B had a 19% reduced transplantation rate (SHR, 0.81 95%CI: 0.73-0.89) and AB had a 28% reduced transplantation rate (SHR: 0.72, 95%CI: 0.61-0.86) in the highest LAS quartile. Additionally, groups B and AB had increased risk of waitlist death/removal in the highest LAS quartile compared with A (SHR: 1.27, 95%CI: 1.08-1.48; SHR: 1.31, 95%CI: 1.00-1.72).

CONCLUSIONS

Waitlist outcomes among ABO blood groups vary depending on illness severity, which is represented by LAS. Blood group O has lower transplantation rates at low LAS while groups B and AB have lower transplantation rates at high LAS.

The Lung Transplant Candidate, Indications, Timing, and Selection Criteria

Lung transplantation can be lifesaving for patients with advanced lung disease. Demographics are evolving with recipients now sicker but determining candidacy remains predicated on one's underlying lung disease prognosis, along with the likelihood of posttransplant success. Determining optimal timing can be challenging, and most programs favor initiating the process early and proactively to allow time for patient education, informed decision-making, and preparation. A comprehensive, multidisciplinary evaluation is used to elucidate disease progrnosis and identify risk factors for poor posttransplant outcomes. Candidacy criteria vary significantly by center, and close communication between referring and transplant providers is necessary to improve access to transplant and 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.

Predictors of lung transplant waitlist mortality for sarcoidosis

RATIONALE

Unlike in other chronic lung diseases, criteria for lung transplant referral in sarcoidosis is not well-established. Waitlist mortality may offer clues in identifying clinical factors that warrant early referral. We aim to identify predictors for transplant waitlist mortality to improve referral criteria for patients with sarcoidosis.

METHODS

We conducted a retrospective analysis of 1034 sarcoidosis patients listed for lung transplantation from May 2005 to May 2019 in the Scientific Registry of Transplant Recipients (SRTR) database. All patients were listed after the establishment of the Lung Allocation Score (LAS). We compared patients who died on the transplant waitlist to those who survived to transplantation. Potential predictors of waitlist mortality were assessed utilizing univariate and multivariate analysis performed via logistic regression modeling.

RESULTS

Of 1034 candidates listed after LAS implementation, 704 were transplanted and 110 died on the waitlist. Significant predictors of waitlist mortality on multivariate analysis include female gender (OR 2.445; 95% CI 1.513-3.951; p = 0.0003) and severe pulmonary hypertension (OR 1.619; 95% CI 1.067-2.457; p = 0.0236). Taller minimum donor height (OR 0.606; 95% CI 0.379-0.969; p = 0.0365) and blood type B (OR 0.524; 95% CI 0.281-0.975 p = 0.0415) were associated with decreased likelihood of death on the waitlist.

CONCLUSION

Among patients with sarcoidosis on the lung transplant waitlist, taller minimum donor height and blood type B were found to be protective factors against death on the waitlist. Female gender and severe pulmonary hypertension have a higher likelihood of death and earlier referral for transplantation in patients with these characteristics should be considered.

Update on Lung Transplantation for Cystic Fibrosis

Lung transplantation provides a treatment option for many individuals with advanced lung disease due to cystic fibrosis (CF). Since the first transplants for CF in the 1980s, survival has improved and the opportunity for transplant has expanded to include individuals who previously were not considered candidates for transplant. Criteria to be a transplant candidate vary significantly among transplant programs, highlighting that the engagement in more than one transplant program may be necessary. Individuals with highly resistant CF pathogens, malnutrition, osteoporosis, CF liver disease, and other comorbidities may be suitable candidates for lung transplant, or if needed, multi-organ transplant. The transplant process involves several phases, from discussion of prognosis and referral to a transplant center, to transplant evaluation, to listing, transplant surgery, and care after transplant. While the availability of highly effective CF transmembrane conductance regulator (CFTR) modulators for many individuals with CF has improved lung function and slowed progression to respiratory failure, early discussion regarding transplant as a treatment option and referral to a transplant program are critical to maximizing opportunity and optimizing patient and family experience. The decision to be evaluated for transplant and to list for transplant are distinct, and early referral may provide a treatment option that can be urgently executed if needed. Survival after transplant for CF is improving, to a median survival of approximately 10 years, and most transplant survivors enjoy significant improvement in quality of life.

Expected effect of the lung Composite Allocation Score system on US lung transplantation

Efforts are underway to transition the current lung allocation system to a continuous distribution framework whereby multiple factors are simultaneously combined into a Composite Allocation Score (CAS) to prioritize candidates for lung transplant. The purpose of this study was to compare discrete CAS scenarios with the current concentric circle-based allocation system to assess their potential effects on the US lung transplantation system using the Scientific Registry of Transplant Recipients' thoracic simulated allocation model. Six alternative CAS scenarios were compared over 10 simulation runs using data from individuals on the lung transplant waiting list from January 1, 2018, through December 31, 2019. Outcome measures were transplant rate, count, waitlist deaths, posttransplant deaths within 2 years, donor-to-recipient distance, and percentage of organs predicted to have flown. Across scenarios, waitlist deaths decreased by 36% to 47%, with larger decreases in deaths at lower placement efficiency weight and higher weighting of the waitlist outcomes. When waitlist outcomes were equally weighted to posttransplant outcomes, more transplants occurred in individuals with the highest expected posttransplant survival. All CAS scenarios led to improved overall measures of equity compared with the current Lung Allocation Score system, including reduced waitlist deaths, and resulted in similar posttransplant survival.

France's New Lung Transplant Allocation System: Combining Equity With Proximity by Optimizing Geographic Boundaries Through the Supply/Demand Ratio

A new lung allocation system was introduced in France in September 2020. It aimed to reduce geographic disparities in lung allocation while maintaining proximity. In the previous two-tiered priority-based system, grafts not allocated through national high-urgency status were offered to transplant centres according to geographic criteria. Between 2013 and 2018, significant geographic disparities in transplant allocation were observed across transplant centres with a mean number of grafts offered per candidate ranging from 1.4 to 5.2. The new system redistricted the local allocation units according to supply/demand ratio, removed regional sharing and increased national sharing. The supply/demand ratio was defined as the ratio of lungs recovered within the local allocation unit to transplants performed in the centre. A driving time between the procurement and transplant centres of less than 2 h was retained for proximity. Using a brute-force algorithm, we designed new local allocation units that gave a supply/demand ratio of 0.5 for all the transplant centres. Under the new system, standard-deviation of graft offers per candidate decreased from 0.9 to 0.5 (p = 0.08) whereas the mean distance from procurement to transplant centre did not change. These preliminary results show that a supply/demand ratio-based allocation system can achieve equity while maintaining proximity.

The new allocation era and policy

Since the Department of Health and Human Services (DHHS) issued the Final Rule in 1998 as a guideline for organ transplantation and allocation policies, the lung allocation system has undergone two major changes. The first change came with the implementation of the lung allocation score (LAS) instead of waiting time as the primary determinant for donor lung allocation. The LAS model helped allocate donor lungs based on medical urgency and likelihood of post-transplant success. The LAS has been successful in prioritizing the sickest candidates and reducing waitlist mortality in line with the Final Rule mandates. However, the LAS model did not address geographic variability in donor lung supply and demand, leading to disparities in waiting list survival based on a patient’s listing location, which was inconsistent with the Final Rule. In an urgent response to a lawsuit filed by a patient demanding broader geographic access to lungs in November 2017, the second major change in lung allocation occurred when the primary allocation unit for donor lungs expanded from the local donation service area (DSA) to a 250-nautical mile radius around the donor hospital. The Organ Procurement and Transplantation Network has since undergone a review of the current organ allocation systems and has approved a continuous organ distribution framework to guide the creation of a new organ allocation system without rigid geographic borders. In this review, we will describe the history of lung allocation, the changes to the allocation system and their consequences, and the potential future of lung allocation policy in the U.S.

Influence of broader geographic allograft sharing on outcomes and cost in smaller lung transplant centers

OBJECTIVE

On November 24, 2017, Organ Procurement and Transplantation Network implemented a change to lung allocation replacing donor service area with a 250 nautical mile radius around donor hospitals. We sought to evaluate the experience of a small to medium size center following implementation.

METHODS

Patients (47 pre and 54 post) undergoing lung transplantation were identified from institutional database from January 2016 to October 2019. Detailed chart review and analysis of institutional cost data was performed. Univariate analysis was performed to compare eras.

RESULTS

Similar short-term mortality and primary graft dysfunction were observed between groups. Decreased local donation (68% vs 6%; P < .001), increased travel distance (145 vs 235 miles; P = .004), travel cost ($8626 vs $14,482; P < .001), and total procurement cost ($60,852 vs $69,052; P = .001) were observed postimplementation. We also document an increase in waitlist mortality postimplementation (6.9 vs 31.6 per 100 patient-years; P < .001).

CONCLUSIONS

Following implementation of the new allocation policy in a small to medium size center, several changes were in accordance with policy intention. However, concerning shifts emerged, including increased waitlist mortality and resource utilization. Continued close monitoring of transplant centers stratified by size and location are paramount to maintaining global availability of lung transplantation to all Americans regardless of geographic residence or socioeconomic status.

Waiting time and mortality rate on lung transplant candidates in Japan: a single-center retrospective cohort study

Background

As lung transplantation (LTX) is a valuable treatment procedure for end-stage pulmonary disease, delayed referral to a transplant center should be avoided. We aimed to conduct a single-center analysis of the survival time after listing for LTX and waitlist mortality in each disease category in a Japanese population.

Methods

We included patients listed for LTX at Tohoku University Hospital from January 2007 to December 2020 who were followed up until March 2021. Pulmonary disease was categorized into the Obstructive, Vascular, Suppurative, Fibrosis, and Allogeneic groups. Risk factors for waitlist mortality were assessed using a Cox proportional hazards model. The Kaplan–Meier method was used to model time to death.

Results

We included 269 LTX candidates. Of those, 100, 72, and 97 patients were transplanted, waiting, and dead, respectively. The median time to LTX and time to death were 796 days (interquartile range [IQR] 579–1056) and 323 days (IQR 129–528), respectively. The Fibrosis group showed the highest mortality (50.9%; p < .001), followed by the Allogeneic (35.0%), Suppurative (33.3%), Vascular (32.1%), and Obstructive (13.1%) groups. The Fibrosis group showed a remarkable risk for waitlist mortality (hazard ratio 3.32, 95% CI 2.11–4.85).

Conclusions

In Japan, the waiting time is extremely long and candidates with Fibrosis have high mortality. There is a need to document outcomes based on the underlying disease for listed LTX candidates to help determine the optimal timing for listing patients based on the estimated local waiting time.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01760-8.

Geographic disparities in lung transplantation in the United States before and after the November 2017 allocation change

BACKGROUND

The primary lung allocation unit was expanded from the donation service area to a 250-mile radius in 2017. Prior to the change, geographic disparities in donor lung availability impacted waitlist outcomes. We sought to determine if the new allocation system improved these disparities.

METHODS

We conducted a retrospective cohort study comparing the 2-year period before and after the change. Donor lung availability was defined as the ratio of donor lungs to waitlist candidates in the primary allocation unit. Transplant centers were divided into quartiles by donor lung availability. Multivariable competing risk models were used to determine the association between lung availability and waitlist outcomes. Multivariable Cox proportional hazards models compared post-transplant survival.

RESULTS

Prior to the allocation change, the unadjusted transplant rate at centers in the lowest and highest quartiles was 132 and 607 transplants per 100 waitlist years. Candidates in the lowest quartile of donor lung availability had a 61% adjusted lower transplantation rate compared to candidates in highest quartile (sub-hazard ratio [sHR]: 0.39, 95% confidence interval [CI]: 0.34-0.44). After the allocation change, the disparity decreased resulting in an unadjusted transplant rate of 141 and 309 among centers in the lowest and highest quartiles. Candidates in the lowest quartile had a 38% adjusted lower transplantation rate compared to those in the highest (sHR: 0.62, 95% CI: 0.57-0.68). There was no significant difference in 1-year post-transplant survival.

CONCLUSIONS

Although the expansion of the primary allocation unit improved disparities in waitlist outcomes without any change in post-transplant survival, there still remain significant differences due to geography.

Geographic disparities in transplantation

PURPOSE OF REVIEW

The Final Rule clearly states that geography should not be a determinant of a chance of a potential candidate being transplanted. There have been multiple concerns about geographic disparities in patients in need of solid organ transplantation. Allocation policy adjustments have been designed to address these concerns, but there is little evidence that the disparities have been solved. The purpose of this review is to describe the main drivers of geographic disparities in solid organ transplantation and how allocation policy changes and other potential actions could impact these inequalities.

RECENT FINDINGS

Geographical disparities have been reported in kidney, pancreas, liver, and lung transplantation. Organ Procurement and Transplant Network has modified organ allocation rules to underplay geography as a key determinant of a candidates' chance of receiving an organ. Thus, heart, lung, and more recently liver and Kidney Allocation Systems have incorporated broader organ sharing to reduce geographical disparities. Whether these policy adjustments will indeed eliminate geographical disparities are still unclear.

SUMMARY

Modern allocation policy focus in patients need, regardless of geography. Innovative actions to further reduce geographical disparities are needed.

Lung transplantation for interstitial lung disease

Lung transplantation (LTx) can be a life-extending treatment option for patients with advanced and/or progressive fibrotic interstitial lung disease (ILD), especially idiopathic pulmonary fibrosis (IPF), fibrotic hypersensitivity pneumonitis, sarcoidosis and connective tissue disease-associated ILD. IPF is now the most common indication for LTx worldwide. Several unique features in patients with ILD can impact optimal timing of referral or listing for LTx, pre- or post-transplant risks, candidacy and post-transplant management. As the epidemiology of LTx and community practices have evolved, recent literature describes outcomes and approaches in higher-risk candidates. In this review, we discuss the unique and important clinical findings, course, monitoring and management of patients with IPF and other progressive fibrotic ILDs during pre-LTx evaluation and up to the day of transplantation; the need for co-management with clinical experts in ILD and LTx is emphasised. Some post-LTx complications are unique in these patient cohorts, which require prompt detection and appropriate management by experts in multiple disciplines familiar with telomere biology disorders and infectious, haematological, oncological and cardiac complications to enhance the likelihood of improved outcomes and survival of LTx recipients with IPF and other ILDs.

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.

Impact of the elimination of the donation service area on United States lung transplant practices and outcomes at high and low competition centers

In November 2017, the donation service area (DSA) was removed as the primary unit of US donor lung allocation. Our primary objective was to evaluate the effect of this change on recipient characteristics, the use of pretransplant extracorporeal membrane oxygenation (ECMO), and on index hospitalization length of stay (LOS) and early posttransplant complications. We also assessed whether these outcomes differed in high and low competition centers, as defined by the Herfindahl-Hirschman Index. Following DSA removal, there was a 9-day decrease in median waitlist time (P = .001) and an increase in median lung allocation score (40 vs 42, P < .0001) but no difference in the need for pretransplant ECMO (incidence rate ratio = 1.16, P = .12). Median LOS increased from 17 to 19 days in the post-DSA era (P = .01). There was no difference in posttransplant outcomes, including prolonged ventilation, new dialysis, or early survival, in the general cohort or between competition groups. High competition centers saw an 18.5-minute increase in ischemic time compared to low competition centers (P = .04) but did not differentially increase single lung transplants or pretransplant ECMO utilization. Overall, DSA elimination was associated with increased posttransplant LOS but no significant differences in pretransplant ECMO or other posttransplant outcomes. Effects were largely similar at low and high competition centers.

A Simple Prioritization Change to Lung Transplant Allocation May Result in Improved Outcomes

BACKGROUND

The lung allocation score (LAS) significantly improved outcomes and wait list mortality in lung transplantation. However, mortality remains high for the sickest wait list candidates despite additional changes to allocation distance. Regulatory considerations of overhauling the current lung allocation system have met significant resistance, and changes would require years to implement. This study evaluates whether a modest change to the current system by prioritization of only high-LAS lung transplant candidates would result in lowered wait list mortality.

METHODS

The Thoracic Simulated Allocation Model was used to evaluate all lung transplant candidates and donor lungs recovered between July 1, 2009 and June 30, 2011. Current lung allocation rules (initial offer within a 250-nautical mile radius for ABO-identical then compatible offers) were run. Allocation was then changed for only patients with an LAS of50 or higher (high-LAS) to be prioritized within a 500-nautical mile radius with no stratification between ABO-identical and compatible offers. Ten iterations of each model were run. Primary end points were wait list mortality and posttransplant 1-year survival.

RESULTS

A total of 6538 wait list candidates and transplant recipients were evaluated per iteration, for a total of 130,760 simulated patients. Compared with current allocation, the adjusted model had a 23.3% decrease in wait list mortality. Posttransplant 1-year survival was minimally affected.

CONCLUSIONS

Without overhauling the entire system, simple prioritization changes to the allocation system for high-LAS candidates may lead to decreased wait list mortality and increased organ use. Importantly, these changes do not appear to lead to clinically significant changes in posttransplant 1-year survival.

Validating thoracic simulated allocation model predictions for impact of broader geographic sharing of donor lungs on transplant waitlist outcomes

BACKGROUND

The thoracic simulated allocation model (TSAM) is used by the Scientific Registry of Transplant Recipients to predict the relative effect of organ allocation policy changes. A new lung allocation policy changing the first unit of allocation from donation service area to 250 nautical miles took effect on November 24, 2017. We studied TSAM's ability to correctly predict trends caused by changes in allocation policy.

METHODS

We compared the population characteristics from the TSAM cohort, 6,386 lung transplant candidates from 2009 to 2011, with the observed cohort of 7,601 candidates from the year before the policy change on November 24, 2017, and the year after. Simulations were run 10 times. Waitlist mortality and transplant rates were calculated and compared with observed mortality and transplant rates in the years before and after the policy change.

RESULTS

TSAM correctly predicted no change in overall waitlist mortality or transplant rates with the policy change. Observed waitlist mortality values were higher, as were transplant rates, because of increased organ donation and population change. TSAM predicted increased transplant rates for diagnosis group D (idiopathic pulmonary fibrosis), decreased rates for group A (chronic obstructive pulmonary disease), and increased rates for candidates with lung allocation score ≥50, but these changes did not occur in the waitlist and transplant populations after the policy change.

CONCLUSIONS

TSAM correctly predicted the relative trends caused by a change in allocation policy but smaller sub-group predictions were not seen.

Perioperative Management of Bleeding and Transfusion for Lung Transplantation

Perioperative allogeneic blood product transfusion is common in lung transplantation and has various implications on the short- and long-term outcomes of lung recipients. This review summarizes the effect of transfusion on outcomes including primary graft dysfunction, chronic lung allograft dysfunction, and all-cause mortality. We outline known risk factors for increased transfusion requirement in lung transplantation and present current evidence regarding the effect of hemostatic agents including antifibrinolytics, recombinant factor VII, and prothrombin complex concentrates. Finally, we highlight the roles of point-of-care coagulation testing and goal-directed transfusion strategies in reducing transfusion requirements in lung transplantation.

Geographic inequity in transplant access

PURPOSE OF REVIEW

Scarcity is a defining feature of the modern transplant landscape, and in light of chronic shortages in donor organs, there is cause for concern about geographic inequities in patients' access to lifesaving resources. Recent policy changes designed to ameliorate unequal donor supply and demand have brought new interest to measuring and addressing disparities at all stages of transplant care. The purpose of this review is to describe an overview of recent literature on geographic inequities in transplant access, focusing on kidney, liver, and lung transplantation and the impact of policy changes on organ allocation.

RECENT FINDINGS

Despite a major change to the kidney allocation policy in 2014, geographic inequity in kidney transplant access remains. In liver transplantation, the debate has centered on the median acuity score at transplantation; however, a more thorough examination of disparities in access and survival has emerged.

SUMMARY

Geographic differences in access and quality of transplant care are undeniable, but existing disparity metrics reflect disparities only among candidates who are waitlisted. Future research should address major gaps in our understanding of geographic inequity in transplant access, including patients who may be transplant-eligible but experience a wide variety of barriers in accessing the transplant waiting list.