Comparison of Outcomes From Smoking and Nonsmoking Donors: Thirteen-Year Experience

Outcomes Following Lung Transplant for COVID-19-Related Complications in the US

Importance

The COVID-19 pandemic led to the use of lung transplant as a lifesaving therapy for patients with irreversible lung injury. Limited information is currently available regarding the outcomes associated with this treatment modality.

Objective

To describe the outcomes following lung transplant for COVID-19-related acute respiratory distress syndrome or pulmonary fibrosis.

Design, Setting, and Participants

In this cohort study, lung transplant recipient and donor characteristics and outcomes following lung transplant for COVID-19-related acute respiratory distress syndrome or pulmonary fibrosis were extracted from the US United Network for Organ Sharing database from March 2020 to August 2022 with a median (IQR) follow-up period of 186 (64-359) days in the acute respiratory distress syndrome group and 181 (40-350) days in the pulmonary fibrosis group. Overall survival was calculated using the Kaplan-Meier method. Cox proportional regression models were used to examine the association of certain variables with overall survival.

Exposures

Lung transplant following COVID-19-related acute respiratory distress syndrome or pulmonary fibrosis.

Main Outcomes and Measures

Overall survival and graft failure rates.

Results

Among 385 included patients undergoing lung transplant, 195 had COVID-19-related acute respiratory distress syndrome (142 male [72.8%]; median [IQR] age, 46 [38-54] years; median [IQR] allocation score, 88.3 [80.5-91.1]) and 190 had COVID-19-related pulmonary fibrosis (150 male [78.9%]; median [IQR] age, 54 [45-62]; median [IQR] allocation score, 78.5 [47.7-88.3]). There were 16 instances of acute rejection (8.7%) in the acute respiratory distress syndrome group and 15 (8.6%) in the pulmonary fibrosis group. The 1-, 6-, and 12- month overall survival rates were 0.99 (95% CI, 0.96-0.99), 0.95 (95% CI, 0.91-0.98), and 0.88 (95% CI, 0.80-0.94) for the acute respiratory distress syndrome cohort and 0.96 (95% CI, 0.92-0.98), 0.92 (95% CI, 0.86-0.96), and 0.84 (95% CI, 0.74-0.90) for the pulmonary fibrosis cohort. Freedom from graft failure rates were 0.98 (95% CI, 0.96-0.99), 0.95 (95% CI, 0.90-0.97), and 0.88 (95% CI, 0.79-0.93) in the 1-, 6-, and 12-month follow-up periods in the acute respiratory distress cohort and 0.96 (95% CI, 0.92-0.98), 0.93 (95% CI, 0.87-0.96), and 0.85 (95% CI, 0.74-0.91) in the pulmonary fibrosis cohort, respectively. Receiving a graft from a donor with a heavy and prolonged history of smoking was associated with worse overall survival in the acute respiratory distress syndrome cohort, whereas the characteristics associated with worse overall survival in the pulmonary fibrosis cohort included female recipient, male donor, and high recipient body mass index.

Conclusions and Relevance

In this study, outcomes following lung transplant were similar in patients with irreversible respiratory failure due to COVID-19 and those with other pretransplant etiologies.

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.

Primary graft dysfunction: what we know

Many advances in lung transplant have occurred over the last few decades in the understanding of primary graft dysfunction (PGD) though effective prevention and treatment remain elusive. This review will cover prior understanding of PGD, recent findings, and directions for future research. A consensus statement updating the definition of PGD in 2016 highlights the growing complexity of lung transplant perioperative care taking into account the increasing use of high flow oxygen delivery and pulmonary vasodilators in the current era. PGD, particularly more severe grades, is associated with worse short- and long-term outcomes after transplant such as chronic lung allograft dysfunction. Growing experience have helped identify recipient, donor, and intraoperative risk factors for PGD. Understanding the pathophysiology of PGD has advanced with increasing knowledge of the role of innate immune response, humoral cell immunity, and epithelial cell injury. Supportive care post-transplant with technological advances in extracorporeal membranous oxygenation (ECMO) remain the mainstay of treatment for severe PGD. Future directions include the evolving utility of ex vivo lung perfusion (EVLP) both in PGD research and potential pre-transplant treatment applications. PGD remains an important outcome in lung transplant and the future holds a lot of potential for improvement in understanding its pathophysiology as well as development of preventative therapies and treatment.

Donor factors and risk of primary graft dysfunction and mortality post lung transplantation: A proposed conceptual framework

Lung transplantation remains a therapeutic option in end-stage lung disease. However, despite advances in the field, early allograft function can be compromised by the development of primary graft dysfunction (PGD); this being the leading cause of morbidity and mortality immediately following the lung transplant procedure. Several recipient factors have been associated with increased risk of PGD, but less is known about donor factors. Aging, tobacco, and chronic alcohol use are donor factors implicated, but how these factors promote PGD remains unclear. Herein, we discuss the available clinical data that link these donor factors with outcomes after lung transplantation, and how they might render the recipient susceptible to PGD through a two-hit process.

Short- and Long-Term Impact of Smoking Donors in Lung Transplantation: Clinical and Pathological Analysis

Background: The use of smoking donors (SD) is one strategy to increase the organ pool for lung transplantation (LT), but the benefit-to-risk ratio has not been demonstrated. This study aimed to evaluate the impact of SD history on recipient outcomes and graft alterations. Methods: LTs in 293 patients were retrospectively reviewed and divided into non-SD (n = 225, group I), SD < 20 pack-years (n = 45, group II), and SD ≥ 20 pack-years (n = 23, group III) groups. Moreover, several lung donor biopsies before implantation (equally divided between groups) were evaluated, focusing on smoking-related lesions. Correlations were analyzed between all pathological data and smoking exposure, along with other clinical parameters. Results: Among the three groups, donor and recipient characteristics were comparable, except for higher Oto scores and age in group III. Group III showed a longer intensive care unit (ICU) and hospital stay compared with the other two groups. This finding was confirmed when SD history was considered as a continuous variable. However, survival and other mid- and long-term major outcomes were not affected by smoking history. Finally, morphological lesions did not differ between the three groups. Conclusions: In our study, SDs were associated with a longer post-operative course, without affecting graft aspects or mid- and long-term outcomes. A definition of pack-years cut-off for organ refusal should be balanced with the other extended criteria donor factors.

Pushing the Envelope for Donor Lungs

The shortage of organ donors remains the major limiting factor in lung transplant, with the number of patients on the waiting list largely exceeding the number of available organ donors. Another issue is the low utilization rate seen in some types of donors. Therefore, novel strategies are continuously being explored to increase the donor pool. Advanced age, smoking history, positive serologies, and size mismatch are common criteria that decrease the rate of use when it comes to organ utilization. Questioning these limitations is one of the purposes of this review. Challenging these limitations by adapting novel donor management strategies could help to increase the rate of suitable lungs for transplantation while still maintaining good outcomes. A second goal is to present the latest advances in organ donation after controlled and uncontrolled cardiac death, and also on how to improve these lungs on ex vivo platforms for assessment and future specific therapies. Finally, pushing the limit of the donor envelope also means reviewing some of the recent improvements made in lung preservation itself, as well as upcoming experimental research fields. In summary, donor lung optimization refers to a global care strategy to increase the total numbers of available allografts, and preserve or improve organ quality without paying the price of early-, mid-, or long-term negative outcomes after transplantation.

Hyperinflation With Pulmonary Dysfunction in Donor Lungs With Smoking History During Lung Perfusion

BACKGROUND

Donor lungs with smoking history are perfused in ex vivo lung perfusion (EVLP) to expand donor lung pool. However, the impact of hyperinflation of perfused lungs in EVLP remains unknown. The aim of this study was to investigate the significance of hyperinflation, using an ex vivo measurement delta V_T, during EVLP in smoker's lungs.

MATERIALS AND METHODS

Seventeen rejected donor lungs with smoking history of median 10 pack-years were perfused for 2 h in cellular EVLP. Hyperinflation was evaluated by measuring delta V_T = inspiratory - expiratory tidal volume (V_T) difference at 1 h. All lungs were divided into two groups; negative delta V_T (n = 11, no air-trapping pattern) and positive delta V_T (n = 6, air-trapping pattern). Transplant suitability was judged at 2 h. By using lung tissue, linear intercept analysis was performed to evaluate the degree of hyperinflation.

RESULTS

The positive delta V_T group had significantly lower transplant suitability than the negative delta V_T group (16 versus 81%, P = 0.035). The positive delta V_T group was significantly associated with lower partial pressure of oxygen/fraction of inspired oxygen ratio ratio (278 versus 356 mm Hg, P = 0.049), higher static compliance (119 versus 98 mL/cm H₂O, P = 0.050), higher lung weight ratio (1.10 versus 0.96, P = 0.014), and higher linear intercept ratio (1.52 versus 0.93, P = 0.005) than the negative delta V_T group.

CONCLUSIONS

Positive delta V_T appears as an ex vivo marker of ventilator-associated lung hyperinflation of smoker's lungs during EVLP.

Effects of drug abuse, smoking and alcohol on donor hearts and lungs

Potential heart and lung donors with a history of illicit drugs and/or smoking and alcohol are frequently offered, though there is no clear guidance on when it is safe to use these organs. A review of the literature on effects of drugs, alcohol and smoking on donor outcomes, and the effects of these on the intact heart and lung was undertaken. There has been a marked increase in deaths from opioid abuse in many developed countries, though recent evidence suggests that outcomes after cardiothoracic transplantation are equivalent to nonopioid donor causes of death. For donor smoking, there is an increased risk with lung transplantation; however, that risk is less when compared to further waiting on the transplant list for a nonsmoking alternative. Heavy alcohol consumption does not adversely affect heart transplantation, and there is no clear evidence of adverse outcomes after lung transplantation. There are no overall effects of cannabis or cocaine on survival after heart or lung transplantation. In all these cases, careful donor assessment can establish if a particular organ can be used. In most cases, use of drugs requires careful assessment, but is not in of itself a contraindication to cardiothoracic transplantation.

Effects of Smoking on Solid Organ Transplantation Outcomes

Tobacco smoking is the leading preventable cause of death worldwide. Both donor and recipient smoking have been shown to increase graft loss and mortality in solid organ transplant recipients in many studies. Only in lung transplants is smoking a universal contraindication to transplantation. Transplant centers implement different policies regarding smoking recipients and allografts from smoking donors. Due to scarcity of available allografts, the risks of smoking have to be weighed against the risks of a longer transplant waitlist period. Although transplant centers implement different strategies to encourage smoking cessation pre- and post-transplant, not many studies have been published that validate the efficacy of smoking cessation interventions in this vulnerable population. This article summarizes the results of studies investigating prevalence, impact on outcomes, and cessationinterventions for smoking in the transplant population. We report herein a review of the elevated risks of infection, malignancy, graft loss, cardiovascular events, and mortality in solid organ transplant populations.

Use of drug intoxicated donors for lung transplant: Impact on survival outcomes

INTRODUCTION

The number of increasing deaths due to the opioid epidemic has led to a potential greater supply of organ donors. There is hesitancy to use drug intoxicated donors, and we evaluated their impact on post-transplant survival.

BACKGROUND

Patients ≥18 years of age undergoing lung transplantation and donors from whom at least one organ was donated between January 2005 and March 2015 were selected from the United Network of Organ Sharing database. Baseline characteristics and post-transplant survival were compared between drug intoxicated and all other donors.

RESULTS

The utilization of drug intoxicated donors increased from 1.86% in 2005 to 6.23% in 2014. The 2 study groups had similar characteristics including age, gender, and Lung Allocation Score. As compared to all other donors, drug intoxicated donors were younger (29.1 ± 9.4 vs 34.6 ± 13.4 years, P < .0001), less likely to be male (52% vs 61%, P < .0001), and had a greater smoking history (14% vs 11%, P .04). There was no difference in post-lung transplant survival at 1, 3, and 5 years between drug intoxicated donors (85%, 64%, and 47%) and non-drug intoxicated donors (83%, 65%, and 51%).

CONCLUSION

Transplantation utilizing drug intoxicated donor lungs has significantly increased over the past decade without significantly impacting post-transplant survival.

Clinical implications of donor age: A single-institution analysis spanning 3 decades

BACKGROUND

We sought to clarify the effect of donor age as a continuous variable on morbidity and mortality in a single-institution experience.

METHODS

From 1986 to 2016, 882 adult lung transplants were performed, including 396 in the lung allocation score era. Kaplan-Meier curves and Cox proportional hazards models were used to evaluate the association of donor age with overall survival and bronchiolitis obliterans syndrome (BOS) score ≥1-free survival. Logistic regression was used to evaluate the association with primary graft dysfunction grade 3. Natural cubic splines were used to explore donor age in a continuous fashion to allow for nonlinear relationships.

RESULTS

In the lung allocation score era, unadjusted 5-year survival was not significantly different between 3 a priori-defined donor age groups: age <40, 40 to 54, and age ≥55 years (64%, 61%, and 69%, P = .8). Unadjusted 5-year freedom from BOS ≥1 was not significantly different (34%, 20%, and 33%, respectively, P = .1). After we adjusted for comorbidities, cubic spline analysis demonstrated no effect between donor age as a continuous variable and hazard for mortality at 5 years. Similarly, no interaction was seen between donor age and risk of BOS or primary graft dysfunction 3. Adjusted analysis of all 882 transplants pre- and postinception of the lung allocation score also showed no effect of age on 10-year survival.

CONCLUSIONS

Long-term survival of lung transplant recipients was not affected by the age of the donor. These findings support the notion that donor age could be relaxed.

Lung donor selection criteria

The criteria that define acceptable physiologic and social parameters for lung donation have remained constant since their empiric determination in the 1980s. These criteria include a donor age between 25-40, a arterial partial pressure of oxygen (PaO2)/FiO2 ratio greater than 350, no smoking history, a clear chest X-ray, clean bronchoscopy, and a minimal ischemic time. Due to the paucity of organ donors, and the increasing number of patients requiring lung transplant, finding a donor that meets all of these criteria is quite rare. As such, many transplants have been performed where the donor does not meet these stringent criteria. Over the last decade, numerous reports have been published examining the effects of individual acceptance criteria on lung transplant survival and graft function. These studies suggest that there is little impact of the historical criteria on either short or long term outcomes. For age, donors should be within 18 to 64 years old. Gender may relay benefit to all female recipients especially in male to female transplants, although results are mixed in these studies. Race matched donor/recipients have improved outcomes and African American donors convey worse prognosis. Smoking donors may decrease recipient survival post transplant, but provide a life saving opportunity for recipients that may otherwise remain on the transplant waiting list. No specific gram stain or bronchoscopic findings are reflected in recipient outcomes. Chest radiographs are a poor indicator of lung donor function and should not adversely affect organ usage aside for concerns over malignancy. Ischemic time greater than six hours has no documented adverse effects on recipient mortality and should not limit donor retrieval distances. Brain dead donors and deceased donors have equivalent prognosis. Initial PaO2/FiO2 ratios less than 300 should not dissuade donor organ usage, although recruitment techniques should be implemented with intent to transplant.

Donor Heart Utilization following Cardiopulmonary Arrest and Resuscitation: Influence of Donor Characteristics and Wait Times in Transplant Regions

Background. Procurement of hearts from cardiopulmonary arrest and resuscitated (CPR) donors for transplantation is suboptimal. We studied the influences of donor factors and regional wait times on CPR donor heart utilization. Methods. From UNOS database (1998 to 2012), we identified 44,744 heart donors, of which 4,964 (11%) received CPR. Based on procurement of heart for transplantation, CPR donors were divided into hearts procured (HP) and hearts not procured (HNP) groups. Logistic regression analysis was used to identify predictors of heart procurement. Results. Of the 4,964 CPR donors, 1,427 (28.8%) were in the HP group. Donor characteristics that favored heart procurement include younger age (25.5 ± 15 yrs versus 39 ± 18 yrs, P ≤ 0.0001), male gender (34% versus 23%, P ≤ 0.0001), shorter CPR duration (<15 min versus >30 min, P ≤ 0.0001), and head trauma (60% versus 15%). Among the 11 UNOS regions, the highest procurement was in Region 1 (37%) and the lowest in Region 3 (24%). Regional transplant volumes and median waiting times did not influence heart procurement rates. Conclusions. Only 28.8% of CPR donor hearts were procured for transplantation. Factors favoring heart procurement include younger age, male gender, short CPR duration, and traumatic head injury. Heart procurement varied by region but not by transplant volumes or wait times.

Can lungs be taken for transplantation from donors with a significant smoking history?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was 'Can lungs be taken for transplantation from donors with a significant smoking history?’. Five papers were found using the reported search that represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. These studies compared the outcome and survival between patients who receive lungs from smokers with those receiving non-smoker lungs. None of these studies were randomized controlled trials. They retrospectively analysed a cohort of patients undergoing lung transplantation for the past 10 years. These studies showed worse outcomes in the early postoperative period, such as longer intensive care unit stay, longer ventilation time and higher early postoperative mortality, with lungs harvested from smokers. Two studies also demonstrated a worse long-term outcome in recipients of lungs from smokers, whereas the other two showed worse results during the early postoperative period only. These latter two studies reported similar survival rates after 3 months and up to 3 years in recipients receiving smoker vs non-smoker lungs. One study, however, showed a better 5-year survival with smoker lungs compared with non-smokers, although in this study, lungs from heavy smokers showed the worse outcome. Despite the difference in long-term results and outcome reported by these authors, all of these studies unanimously indicate that lungs from smokers should not be rejected, as survival in these patients receiving smoker lungs is still significantly higher in 3 and 5 years compared with that in those who remain on the transplant waiting list. In conclusion, the current evidence in the literature suggests that lungs from smokers can be used for transplantation. Patients should, however, be fully informed of the risks involved with these lungs and the worse outcome compared with those receiving non-smoker lungs.

Tobacco smoking and solid organ transplantation

Smoking, both by donors and by recipients, has a major impact on outcomes after organ transplantation. Recipients of smokers' organs are at greater risk of death (lungs hazard ratio [HR], 1.36; heart HR, 1.8; and liver HR, 1.25), extended intensive care stays, and greater need for ventilation. Kidney function is significantly worse at 1 year after transplantation in recipients of grafts from smokers compared with nonsmokers. Clinicians must balance the use of such higher-risk organs with the consequences on waiting list mortality if the donor pool is reduced further by exclusion of such donors. Smoking by kidney transplant recipients significantly increases the risk of cardiovascular events (29.2% vs. 15.4%), renal fibrosis, rejection, and malignancy (HR, 2.56). Furthermore, liver recipients who smoke have higher rates of hepatic artery thrombosis, biliary complications, and malignancy (13% vs. 2%). Heart recipients with a smoking history have increased risk of developing coronary atherosclerosis (21.2% vs. 12.3%), graft dysfunction, and loss after transplantation. Self-reporting of smoking is commonplace but unreliable, which limits its use as a tool for selection of transplant candidates. Despite effective counseling and pharmacotherapy, recidivism rates after transplantation remain high (10-40%). Transplant services need to be more proactive in educating and implementing effective smoking cessation strategies to reduce rates of recidivism and the posttransplantation complications associated with smoking. The adverse impact of smoking by the recipient supports the requirement for a 6-month period of abstinence in lung recipients and cessation before other solid organs.

Effect of donor smoking on survival after lung transplantation: a cohort study of a prospective registry

BACKGROUND

The risk that a positive smoking history in lung donors could adversely affect survival of transplant recipients causes concern. Conversely, reduction of the donor pool by exclusion of donors with positive smoking histories could compromise survival of patients waiting to receive a transplant. We examined the consequences of donor smoking on post-transplantation survival, and the potential effect of not transplanting lungs from such donors.

METHODS

We analysed the effect of donor smoking on 3 year survival after first adult lung transplantation from brain-dead donors done between July 1, 1999, and Dec 31, 2010, by Cox regression modelling of data from the UK Transplant Registry. We estimated the effect of acceptance of lungs from donors with positive smoking histories on survival and compared it with the effect of remaining on the waiting list for a potential transplant from a donor with a negative smoking history donor, by analysing all waiting-list registrations during the same period with a risk-adjusted sequentially stratified Cox regression model.

FINDINGS

Of 1295 lung transplantations, 510 (39%) used lungs from donors with positive smoking histories. Recipients of such lungs had worse 3 year survival after transplantation than did those who received lungs from donors with negative smoking histories (unadjusted hazard ratio [HR] 1·46, 95% CI 1·20-1·78; adjusted HR 1·36, 1·11-1·67). Independent factors affecting survival were recipient's age, donor-recipient cytomegalovirus matching, donor-recipient height difference, donor's sex, and total ischaemic time. Of 2181 patients registered on the waiting list, 802 (37%) died or were removed from the list without receiving a transplant. Patients receiving lungs from donors with positive smoking histories had a lower unadjusted hazard of death after registration than did those who remained on the waiting list (0·79, 95% CI 0·70-0·91). Patients with septic or fibrotic lung disease registered in 1999-2003 had risk-adjusted hazards of 0·60 (95% CI 0·42-0·87) and 0·39 (0·28-0·55), respectively.

INTERPRETATION

In the UK, an organ selection policy that uses lungs from donors with positive smoking histories improves overall survival of patients registered for lung transplantation, and should be continued. Although lungs from such donors are associated with worse outcomes, the individual probability of survival is greater if they are accepted than if they are declined and the patient chooses to wait for a potential transplant from a donor with a negative smoking history. This situation should be fully explained to and discussed with patients who are accepted for lung transplantation.

FUNDING

National Health Service Blood and Transplant.

Does the use of extended criteria donors influence early and long-term results of lung transplantation?

A best evidence topic was constructed according to a structured protocol. The question addressed was whether the presence of extended criteria donors influences the early and long-term results in patients referred for lung transplantation. Of the 30 papers found using a report search, 14 presented the best evidence to answer the clinical question. The authors, journal, date, country of publication, study type, group studied, relevant outcomes and results of these papers are given. In total, we recorded 10 retrospective studies that considered all the donor criteria for comparing marginal donors (MDs) and standard donors. On the one hand, six of them showed no difference between the two groups in terms of early and long-term results. On the other hand, four studies demonstrated a negative impact of MDs on various early outcomes (mortality, primary graft dysfunction, duration of mechanical ventilation, length of stay in intensive care unit), whereas no significant negative influence on survival has ever been described when screening MD results. More precisely, when analysing the role of individual factors of marginality, as done in two of the 14 studies, a significant negative impact was observed for a low level of PaO(2) at the time of harvesting, positive bronchoscopy and smoking history. More specifically, the first two criteria have been validated by several authors, both in multicentre and cohort studies. Finally, the importance of avoiding the donation of the lung from an MD to a high-risk recipient emerged, whereas the association with single or bilateral transplants remains more controversial. Hence, current evidence suggests that there are no contraindications-given the absence of negative impact on survival-for the use of MDs for the transplant of a proposed standard receiver. However, given the low level of evidence of published studies, caution is necessary in order to avoid organ shortage, despite these encouraging results.