Right single lung transplantation or double lung transplantation compared with left single lung transplantation in chronic obstructive pulmonary disease

Two Staged Single Lung Transplants in the Current Era: A United Network for Organ Sharing Study

BACKGROUND

We hypothesized that outcomes after 2 staged, contralateral single lung transplantation procedures (SSLTs) may be equivalent to those of double lung transplantation (DLT) by capitalizing on the known long-term survival advantages of DLT.

METHODS

Using the United Network for Organ Sharing data set (1987-2018), the largest national data set available, the outcomes of 278 SSLTs were retrospectively analyzed and compared with the outcomes of 21,121 standard DLTs.

RESULTS

During SSLT, the median interval between the 2 transplants was 960 days, and the indication for the second transplant was most often chronic lung allograft dysfunction (n = 148; 53.2%) or the same disease that necessitated the first transplant (n = 81; 29.1%). The patients who underwent SSLT were significantly older and had a higher baseline creatinine level than the patients who underwent DLT. Most posttransplantation short-term outcomes were equivalent between the second stage of SSLT and DLT, but renal insufficiency requiring hemodialysis was notably higher after SSLT. There were no differences in long-term survival. In multivariate analysis, baseline creatinine, O2 support at rest, ventilator support at the time of the second transplantation, and posttransplantation renal insufficiency requiring dialysis were independent predictors of 1-year mortality after SSLT.

CONCLUSIONS

Over a study period of 30 years, long-term survival after SSLT was comparable with survival after DLT. With further analysis of individual risk profiles, including the contributions of preoperative renal function and functional status, SSLT can be a valuable option for patients who would have undergone single lung transplantation to reap the long-term benefits of a second transplant.

Surgical and Interventional Approaches in COPD

Many patients suffer from complaints of dyspnea, cough, and sputum production, clinical symptoms that hallmark the structural abnormalities that are present in patients with COPD. Although pharmacologic and non-pharmacologic medical therapies help reduce these symptoms, many of these symptoms, especially dyspnea, remain unchecked and contribute to the burden of disease in patients with COPD. Over the last 3 decades, several surgical and interventional treatments delivered via a bronchoscopic approach have been developed to complement medical therapies and show promise to improve patient outcomes. Surgical and interventional treatments target structural abnormalities of the airway and lung parenchyma that can be identified with a combination of imaging and physiological testing, factors that are key to select patients most likely to benefit from these treatments. This paper reviews surgical and bronchoscopic interventional treatment options for patients with emphysema and airways disorders.

Lung transplantation for COPD/pulmonary emphysema

COPD and α-1 antitrypsin deficiency emphysema remain one of the major indications for lung transplantation. If all other treatment possibilities are exhausted or not possible (including rehabilitation, oxygen therapy, noninvasive ventilation, lung volume reduction), patients may qualify for lung transplantation. Strict selection criteria are implemented with a lot of relative and absolute contraindications. Because of an ongoing donor shortage, only a minority of endstage COPD patients will finally get transplanted. The procedure may involve a single or a double lung transplantation, dependent on the experience of the centre, the waiting list, the availability of donor lungs and the patient's risk-benefit ratio. In general, the life expectancy as well as the health-related quality of life after lung transplantation for COPD are usually increased, and may be somewhat better after double compared with single lung transplantation. Several specific complications can be encountered, such as the development of solid organ cancer and chronic lung allograft dysfunction, which develops in up to 50% of patients within 5 years of their transplant and has a major impact on long-term survival, because of the current inefficient treatment modalities.

Ex vivo lung evaluation of single donor lungs when the contralateral lung is rejected increases safe use

OBJECTIVE

The decision to perform a single-lung transplant (SLT) when the contralateral donor lung is rejected is a challenging scenario. The introduction of ex vivo lung perfusion (EVLP) has improved donor lung assessment, and we hypothesize that it has improved SLT outcomes in this setting.

METHODS

A retrospective single-center review of all SLTs performed between 2000 and 2017 was performed in which the years 2000 to 2008 were considered the "pre-EVLP era" and 2009 to 2017 the "EVLP era." Recipients of SLT lungs when the contralateral lung was declined were classified into 3 groups: (1) Pre-EVLP era, (2a) EVLP era but EVLP not used, and (2b) EVLP era and EVLP used. The outcomes of interest were survival, time-to-extubation, and intensive care unit and hospital stay.

RESULTS

Among 1692 transplants between 2000 and 2017, 244 (14%) were SLT. SLT rate was similar between eras (pre-EVLP 16% vs EVLP 15%), but more SLTs were performed where the contralateral lung was declined in the EVLP era (pre-EVLP 32% vs EVLP 45%, P = .04). Lungs evaluated on EVLP had lower procurement partial pressure of oxygen and were more often from donation after cardiac death donors. Recipients were generally also sicker, with a greater proportion of rapidly deteriorating recipients. Despite this, outcomes were similar between eras with a trend towards lower 30-day mortality in the EVLP era.

CONCLUSIONS

The availability of EVLP allowed for better evaluation of marginal single lungs when the contralateral was declined. This has led to increased use rates with preserved outcomes despite use of more extended criteria organs.

Lung transplantation for chronic obstructive pulmonary disease: A call to modify the lung allocation score to decrease waitlist mortality

OBJECTIVE

Approximately 40% of lung transplants for chronic obstructive pulmonary disease (COPD) in the lung allocation score era are single lung transplantations (SLTs). We hypothesized that double lung transplantation (DLT) results in superior survival, but that mortality on the waitlist may compel clinicians to perform SLT. We investigated both waitlist mortality in COPD patients with restricted versus unrestricted listing preferences and posttransplant survival in SLT versus DLT to identify key predictors of mortality.

METHODS

A retrospective analysis of waitlist mortality and posttransplant survival in patients with COPD was conducted using post-lung allocation score data from the United Network for Organ Sharing database between 2005 and 2018.

RESULTS

Of 6740 patients with COPD on the waitlist, 328 (4.87%) died and 320 (4.75%) were removed due to clinical deterioration. Median survival on the waitlist was significantly worse in patients listed as restricted for DLT (4.39 vs 6.09 years; P = .002) compared with patients listed as unrestricted (hazard ratio, 1.34; 95% CI, 1.13-1.57). Factors that increase waitlist mortality include female sex, increased pulmonary artery pressure, and increased wait time. Median posttransplant survival was 5.3 years in SLT versus 6.5 years in DLT (P < .001). DLT recipients are younger, male patients with a higher lung allocation score. The survival advantage of DLT persisted in adjusted analysis (hazard ratio, 0.819; 95% CI, 0.741-0.905).

CONCLUSIONS

Restricted listing preference is associated with increased waitlist mortality, but DLT recipients have superior posttransplant survival. Because the lung allocation score does not prioritize COPD, concern for increased waitlist mortality with restricted listing preference may drive continued use of SLT despite better posttransplant survival in DLT.

Current state of clinical trials regarding lung transplant rejection

BACKGROUND

Over the last several decades, the field of lung transplantation has made significant advances. Despite these advancements, morbidity and mortality rates are still high when compared to other solid organ transplants. Clinical trials have a significant role bringing new medications with better effects than their predecessors. Our study is critical in evaluating and tracking clinical trials involving rejection of lung transplant, with a focus on interventional therapeutic trials.

METHODS

On November 3, 2021, we searched clinicaltrial.gov for interventional clinical trials related to lung transplant rejection. A total of 39 clinical trials are included in this study. Characteristics on each trial were gathered. Linked publications were searched using Medline/PubMed and Embase/Scopus, and their content reviewed and summarized.

RESULTS

The majority of trials were divided into completed (15 out of 39) and recruiting (12 out of 39). 17 trials had between 11 and 50 participants, and 8 had above 100. Only 1 trial lasted >10 years, and the average length of all trials was 3.6 years. The majority of trials were conducted in Europe/UK/Russia and the United States/Canada (17 and 18 trials, respectively). The results were provided in 3 trials, and also published in 3, showing a decrease in the rate of patients reaching an endpoint after chronic rejection with liposomal aerosol cyclosporine, a decrease in their cytokines level, and an increase in their 5-year-survival rate compared to the oral conventional immunosuppressant, the benefit of sirolimus in decreasing the acute rejection rate and severity in comparison to azathioprine, and its efficacy against cytomegalovirus infections. Other trials revealed the benefits of azithromycin in remarkably decreasing airways and systemic inflammation, with a concomitant decline in the risk of both BOS and CLAD; highlighting the deleterious effects of air pollution after transplantation surgery; and using the grading biopsy as a post-transplantation assessment tool.

CONCLUSION

This study is a descriptive analysis of clinical trials targeting lung transplant rejection. This study shows the low number of trials, lack of variety in location and low publishing rates. Although focus of published trials was mainly towards azithromycin, bronchiolitis obliterans syndrome, air pollution, and biopsy in grading, a remarkable progress was realized concerning therapies, leading to less complications with a delay of chronic rejection onset, and an increase in overall survival. This sheds the light on the need for managing research efforts to fulfill any lack in specific domain, leading to new, effective therapies, and providing thereby much more benefit.

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.

Donor quality assessment and size match in lung transplantation

Careful donor quality assessment and size match can impact long-term survival in lung transplantation. With this article, we review the conceptual and practical aspects of the preoperative donor lung quality assessment and size matching.

Factors affecting complications development and mortality after single lung transplant

Lung transplantation (LT) is a life-saving therapeutic procedure that prolongs survival in patients with end-stage lung disease. Furthermore, as a therapeutic option for high-risk candidates, single LT (SLT) can be feasible because the immediate morbidity and mortality after transplantation are lower compared to sequential single (double) LT (SSLTx). Still, the long-term overall survival is, in general, better for SSLTx. Despite the great success over the years, the early post-SLT period remains a perilous time for these patients. Patients who undergo SLT are predisposed to evolving early or late postoperative complications. This review emphasizes factors leading to post-SLT complications in the early and late periods including primary graft dysfunction and chronic lung allograft dysfunction, native lung complications, anastomosis complications, infections, cardiovascular, gastrointestinal, renal, and metabolite complications, and their association with morbidity and mortality in these patients. Furthermore, we discuss the incidence of malignancy after SLT and their correlation with immunosuppression therapy.

Comparing outcomes in patients with end-stage chronic obstructive pulmonary disease: single versus bilateral lung transplants

OBJECTIVES

Debate continues on whether a bilateral (BLT) or a single lung transplantation (SLT) is preferred for patients with end-stage chronic obstructive pulmonary disease (COPD). The purpose of this study is to examine the interplay between patient age and transplant type on survival outcomes.

METHODS

We performed a retrospective study of lung transplants for COPD at our centre from February 2012 to March 2020 (n = 186). Demographics and clinical parameters were compared between patients based on their age (≤65 vs >65 years old) and type of transplant (single vs bilateral). Cox proportional hazards regression was also performed. P-values <0.05 were considered significant.

RESULTS

Of the 186 patients with COPD who received lung transplants, 71 (38.2%) received BLTs and 115 (61.8%) received SLTs. There was no significant difference in survival outcomes when looking at patients with single versus BLTs (P = 0.870). There was also no difference in survival between the 2 age groups ≤65 versus > 65 years (P = 0.723). The Cox model itself also did not show a statistically significant improvement in survival outcomes (P = 0.126).

CONCLUSIONS

Lung transplant outcomes in patients with end-stage COPD demonstrated non-inferior results in patients with an SLT compared to patients with a BLT. When we compared the age groups, neither transplant type showed superior survival benefits, suggesting there may be some utility in an SLT in younger recipients.