Post-transplant Baseline FEV1 and the Development of Bronchiolitis Obliterans Syndrome: An Important Confounder?

Long-term outcomes of lung transplantation with ex vivo lung perfusion technique

Ex vivo lung perfusion (EVLP) has demonstrated encouraging short- and medium-term outcomes with limited data available on its long-term outcomes. This study assesses (1) EVLP long-term outcomes and (2) EVLP era-based sub-analysis in addition to secondary outcomes of recipients with EVLP-treated donor lungs compared with recipients of conventionally preserved donor lungs in unmatched and propensity score-matched cohorts. Double lung transplants performed between 1st January 2012 and 31st December 2021 were included. A total of 57 recipients received EVLP-treated lungs compared to 202 unmatched and 57 matched recipients who were subjected to non-EVLP-treated lungs. The EVLP group had a significantly lower mean PaO2/FiO2 ratio and significantly higher mean BMI than the non-EVLP group in the unmatched and matched cohorts. The proportion of smoking history in the unmatched cohort was significantly higher in the EVLP group, while a similar smoking history was demonstrated in the matched cohorts. No difference was demonstrated in overall freedom from death and retransplantation between the groups in the unmatched and matched cohorts (unmatched: hazard ratio (HR) 1.28, 95% confidence interval (CI) 0.79-2.07, P = 0.32; matched: HR 1.06, 95% CI 0.59-1.89). P = 0.89). In the unmatched cohort, overall freedom from chronic allograft dysfunction (CLAD) was significantly different between the groups (HR 1.64, 95% CI 1.07-2.52, P = 0.02); however, the cumulative CLAD incidence was similar (HR 0.72, 95% CI 0.48-1.1, P = 0.13). In the matched cohort, the overall freedom from CLAD (HR 1.69, 95% CI 0.97-2.95, P = 0.06) and cumulative CLAD incidence (HR 0.91, 95% CI 0.37-2.215, P = 0.83) were similar between the groups. The EVLP era sub-analysis of the unmatched cohort in 2012-2014 had a significantly higher cumulative CLAD incidence in the EVLP group; however, this was not demonstrated in the matched cohort. All secondary outcomes were similar between the groups in the unmatched and matched cohorts. In conclusion, transplantation of marginal donor lungs after EVLP evaluation is non-detrimental compared to conventionally preserved donor lungs in terms of mortality, retransplantation, cumulative CLAD incidence, and secondary outcomes. Although the unmatched EVLP era of 2012-2014 had a significantly higher cumulative CLAD incidence, no such finding was demonstrated in the matched cohort of the same era.

A European Multi-Center Analysis of Extracorporeal Photopheresis as Therapy for Chronic Lung Allograft Dysfunction

Extracorporeal photopheresis (ECP) is used by few lung transplant centers to treat chronic lung allograft dysfunction (CLAD). Although reported results suggest a beneficial effect on CLAD progression, evidence is limited to single center experiences. The aim of this study is to analyze outcomes of ECP in a large multicenter European cohort. The primary endpoint was patient survival after initiation of ECP. This study included 631 patients, 87% suffered from bronchiolitis obliterans syndrome (BOS), and 13% had restrictive allograft syndrome (RAS). Long-term stabilization was achieved in 42%, improvement in 9%, and no response in 26%. Within the first 12 months of therapy, 23% of patients died. Patients' survival after initiation of ECP at 5 years was 56% in stable, 70% in responders, and 35% in non-responders (p = 0.001). In multivariable Cox regression, both stabilization (HR: 0.48, CI: 0.27-0.86, p = 0.013) and response (HR: 0.11, CI: 0.04-0.35, p < 0.001) to ECP were associated with survival. Absolute FEV1 at baseline was also protective (HR: 0.09, CI: 0.01-0.94, p = 0.046). RAS phenotype was the only risk factor for mortality (HR: 2.11, 1.16-3.83, p = 0.006). This study provides long-term outcomes of ECP use in CLAD patients in the largest published cohort to date. Two-thirds of the cohort had a sustained response to ECP with excellent long-term results.

Airway oscillometry parameters in baseline lung allograft dysfunction: Associations from a multicenter study

BACKGROUND

Baseline lung allograft dysfunction (BLAD), the failure to achieve ≥80%-predicted spirometry after lung transplant (LTx), is associated with impaired survival. Physiologic abnormalities in BLAD are poorly understood. Airway oscillometry measures respiratory system mechanics and may provide insight into understanding the mechanisms of BLAD.

OBJECTIVES

This study aims to describe and measure the association between airway oscillometry parameters [Reactance (X_rs5, Ax), Resistance (R_rs5, R_rs5-19)] (1) stable LTx recipients, comparing those with normal spirometry and those with BLAD; and (2) in recipients with chronic lung allograft dysfunction (CLAD), comparing those with normal baseline spirometry and those with BLAD.

METHODS

A multi-center cross-sectional study was performed including bilateral LTx between January 2020 and June 2021. Participants performed concurrent airway oscillometry and spirometry. Multivariable logistic regression was performed to measure the association between oscillometry parameters and BLAD.

RESULTS

A total of 404 LTx recipients performed oscillometry and 253 were included for analysis. Stable allograft function was confirmed in 149 (50.2%) recipients (92 (61.7%) achieving normal spirometry and 57 (38.3%) with BLAD). Among stable LTx recipients, lower X_rs5 Z-Score (aOR 0.50 95% CI 0.37-0.76, p = 0.001) was independently associated with BLAD. CLAD was present in 104 (35.0%) recipients. Among recipients with CLAD, lower X_rs5 Z-Score (aOR 0.73 95% CI 0.56-0.95, p = 0.02) was associated with BLAD.

CONCLUSIONS

Oscillometry provides novel physiologic insights into mechanisms of BLAD. The independent association between X_rs5 and BLAD, in both stable recipients and those with CLAD suggests that respiratory mechanics, in particular abnormal elastance, is an important physiologic feature. Further longitudinal studies are needed to understand the trajectory of oscillometry parameters in relation to allograft outcomes.

Management and outcome of obstructive airway complications after lung transplantation - a 12-year retrospective cohort study

BACKGROUND

Obstructive airway complications (OACs) represent a significant problem after lung transplantation (LTx). Bilateral OACs after double lung transplantation are infrequently reported.

OBJECTIVES

The aim of this study was to investigate management and outcome of OAC.

DESIGN

Retrospective single-center cohort study.

METHODS

Adult patients with bilateral LTx performed between 2010 and 2021 were included. Patients with follow-ups of less than 3 months and after heart-lung transplantation were excluded. OAC was defined either as the need for stenting, surgical revision, or balloon dilatation. Outcome parameters included graft survival, graft function, quality of life, and management.

RESULTS

During the study period, 1,170 patients were included. Hundred thirty-five (11.5%) patients developed OAC. Forty-six (4.4%) patients had significant bilateral OAC. Thirty-seven (80%) bilateral OAC patients were treated by stent insertion; in 34 patients, biodegradable stents were used. The median number of bronchoscopies in bilateral OAC was 26 during the first postoperative year compared with nine in controls (p < 0.001). Fourteen OAC patients (n = 10 bilateral) underwent surgical revision including six re-do transplantations. Graft loss occurred significantly more frequently in patients with bilateral OAC with a graft survival of 63% and 50% in these after 3 and 5 years compared with 83% and 73% in controls without OAC (p < 0.001). Baseline forced expiratory volume in 1 s (FEV1) in patients with bilateral OAC was median 58% predicted in comparison with 90% in controls (p < 0.001). Quality of life was significantly reduced.

CONCLUSION

Bilateral OACs impose a high burden of disease on patients after lung transplantation and were associated with early and late graft loss. Affected patients' OAC demonstrated reduced graft function and impaired quality of life. Most OACs were managed by bronchoscopy preferably by non-permanent stenting. Surgery including re-do transplantation was used in selected cases.

Assessing treatment outcomes in CLAD: The Hannover-extracorporeal photopheresis model

BACKGROUND

Chronic lung allograft dysfunction (CLAD) is a leading cause of graft loss in lung transplantation. Despite this, convincing treatment data is lacking, and protocols vary widely between centers. CLAD phenotypes exist, but phenotype transitioning has increased the challenge of designing clinically relevant studies. Extracorporeal photopheresis (ECP) has long been a suggested salvage treatment, but efficacy appears unpredictable. This study describes our experiences with photopheresis, using novel temporal phenotyping to illustrate the clinical course.

METHODS

Retrospective analysis of patients completing ≥3 months of ECP for CLAD between 2007 and 2022 was performed. A latent class analysis employing a mixed-effects model was performed, deriving patient subgroups based on spirometry trajectory over the 12 months prior to photopheresis until graft loss or 4 years post photopheresis initiation. The resulting temporal phenotypes were compared in terms of treatment response and survival outcomes. Linear discriminatory analysis was used to assess phenotype predictability, relying solely on data available at photopheresis initiation.

RESULTS

Data from 5,169 outpatient attendances in 373 patients was used to construct the model. Five trajectories were identified, with uniform spirometry changes evident following 6 months of photopheresis. Outcomes were poorest in Fulminant patients (N = 25, 7%) with median survival of 1 year. In the remainder, poorer lung function at initiation led to poorer outcomes. The analysis revealed important confounders, affecting both decision-making and outcome interpretation.

CONCLUSIONS

Temporal phenotyping provided novel insights into ECP treatment response in CLAD, particularly the importance of timely intervention. Limitations in % Baseline values in guiding treatment decisions warrant further analysis. Photopheresis may have a more uniform effect than previously thought. Predicting survival at ECP initiation appears feasible.

Relationship between FEV1 decline and mortality in patients with bronchiolitis obliterans syndrome-a systematic literature review

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is one of the most severe complications and the leading cause of late mortality and morbidity after lung transplantation (LT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT). No approved treatment for BOS is available. This review aimed to systematically identify and summarise the findings regarding the relationship between FEV₁ decline and mortality in patients who developed BOS following LT or allo-HSCT.

METHODS

A systematic literature search was performed in the Medline, Embase and Cochrane reviews databases. Of the 501 potential studies identified 25 met inclusion criteria and were analysed.

RESULTS

Overall, 13 studies reported a relationship between FEV₁ and mortality, and 12 studies reported both mortality and FEV₁ results but did not investigate the relationship between them. There was heterogeneity in the analyses, which investigated the relationship between FEV₁ decline and mortality across the studies in terms of levels of lung functioning, comparison to a control group, treatment, and statistical methodology; nevertheless, a clear and consistent increase in the risk of death associated with FEV₁ decrease was seen in the analysed studies.

CONCLUSIONS

The systematic literature review identified studies and findings that support a relationship between FEV₁ and mortality, with a decrease in FEV₁ being statistically associated with increased risk of death. Knowing that lower FEV₁ levels are associated with higher mortality rates may help assess the condition of a patient with BOS and monitor future treatment effectiveness. However, more evidence is needed to further investigate this relationship and to verify its clinical usefulness.

Characteristics and clinical implications of pleural effusions after lung transplantation: A retrospective analysis of 195 thoracocenteses in 113 patients

Despite advances in lung transplantation (LTx), morbidity, and mortality are high. We hypothesized that pleural effusions requiring thoracocentesis lead to poor outcomes after LTx. We performed a single-center retrospective analysis of thoracocenteses after initial hospital discharge in LTx patients between March 2008 and September 2020 to identify risk factors, etiologies, and outcomes. Of the 1223 patients included, 113 patients (9.2%) required a total of 195 thoracocenteses. The cumulative incidence of thoracocentesis was 10.6% at 1 year and 14.2% at 5 years after transplantation. We observed a bimodal distribution of pleural effusion onset with a threshold at 6 months. Late-onset effusions were mostly of malignant or cardiac origin. We observed a high rate of nonspecific effusions (41.5%) irrespective of the timepoint post-transplantation. Patients with late-onset effusions had significantly lower survival compared to a matched controlled group (HR 2.43; 95% CI (1.27-4.62). All pulmonary function parameters were significantly decreased in patients requiring thoracocentesis compared to matched controls. Male sex and re-transplantation were risk factors for pleural effusions. In conclusion, pleural effusions requiring thoracocentesis occur frequently in LTx patients and lead to a reduced long-term allograft function. Late-onset effusions are associated with a lower survival.

Variation in Time to Peak Values for Different Lung Function Parameters After Double Lung Transplantation

BACKGROUND

Establishment of baseline values for forced expiratory volume in the first second (FEV₁), forced vital capacity (FVC), or total lung capacity (TLC) is required when diagnosing and phenotyping chronic lung allograft dysfunction after lung transplant. It is generally accepted that the baseline (peak) values of these parameters occur simultaneously, but this assumption has not been substantiated for TLC.

METHODS

All lung function measurements in all double lung transplant recipients from a single center in the period from 1992-2014 were included. Time to baseline FEV₁ was assessed according to standards from the International Society for Heart and Lung Transplantation, and time to peak FVC, TLC, and diffusion capacity for carbon monoxide were evaluated.

RESULTS

A total of 288 double lung transplants surviving more than 3 months after transplant were included. Baseline FEV₁ occurred at a median of 0.77 years post transplant and was statistically different from median times to the peak FVC (1.02 years), to peak TLC (1.37 years), and to peak diffusion capacity for carbon monoxide 1.04 years post transplant (all log-rank P < .001). At the time of baseline FEV1, FVC, and TLC were at a mean of 96% and 95% of their peak values, respectively.

CONCLUSION

The peak lung function is reached at different time points for different parameters post transplant with FEV₁ baseline occurring first. For most patients values of FVC and TLC obtained at time for baseline FEV₁ is a good estimate of peak values, but in a small percentage of patients this procedure may jeopardize phenotyping of chronic lung allograft dysfunction based solely on lung function parameters.

Pleural catheter placement and intrapleural fibrinolysis following lung transplantation

BACKGROUND

This study aimed to investigate the characteristics of lung transplant recipients requiring additional pleural drainage catheters early post-lung transplantation and to determine the safety and efficacy of intrapleural fibrinolytics in these patients.

METHODS

A retrospective review of lung transplant recipients at a single center was performed. Patient and transplant characteristics, placement of pleural drainage catheters within 90 days of transplant, and use of intrapleural fibrinolytics were determined.

RESULTS

Out of 128 patients who underwent lung transplantation, 54 patients required 86 additional chest tubes, the majority of which were size 14 French or smaller. Pleural effusion was the most common indication for tube placement. Patients who required additional chest tubes were more likely to have chronic obstructive pulmonary disease than those who did not. Use of intrapleural fibrinolytics led to radiographic improvement in 77.8% of patients and was not associated with bleeding, pneumothorax, or mortality within 30 days.

CONCLUSIONS

Use of small-bore chest tubes and intrapleural fibrinolytics can be safe and effective in lung transplant recipients with persistent pleural effusions.

25-year follow-up after lung transplantation at Lund University Hospital in Sweden: superior results obtained for patients with cystic fibrosis

OBJECTIVES

In Sweden, two centres perform lung transplantation for a population of about 9 million and the entire population is covered for lung transplantation by government health insurance. Lund University Hospital is one of these centres. This retrospective report reviews the 25-year experience of the Skåne University Hospital Lung Transplant Program with particular emphasis on short-term outcome and long-term survival but also between different subgroups of patients and types of transplant [single-lung transplantation (SLTx) versus double-lung transplantation (DLTx)] procedure performed.

METHODS

Between January 1990 and June 2014, 278 patients underwent lung transplantation at the Skåne University Hospital Sweden. DLTx was performed in 172 patients, SLTx was performed in 97 patients and heart-lung transplantation was performed in 9 patients. In addition, 15 patients required retransplantation (7 DLTx and 8 SLTx).

RESULTS

Overall 1-, 5-, 10-, 15- and 20-year survival rates were 88, 65, 49, 37 and 19% for the whole cohort. DLTx recipients showed 1-, 5-, 10- and 20-year survival rates of 90, 71, 60 and 30%, compared with SLTx recipients with 1-, 5-, 10- and 20-year survival rates of 83, 57, 34 and 6% (P < 0.05), respectively. Comparing the use of intraoperative extracorporeal membrane oxygenation, extracorporeal circulation (ECC) and no circulatory support in the aspect of survival, a significant difference in favour of intraoperative ECC was seen.

CONCLUSIONS

Superior long-term survival rates were seen in recipients diagnosed with cystic fibrosis, α1-antitrypsin deficiency and pulmonary hypertension. DLTx showed better results compared with SLTx especially at 10 years post-transplant. In the present study, we present cumulative incidence rates of bronchiolitis obliterans syndrome of 15% at 5 years, 26% at 10 years and 32% at 20 years post-transplant; these figures are in line with the lowest rates presented internationally.

Bronchiolitis obliterans syndrome is not specific for bronchiolitis obliterans in pediatric lung transplant

BACKGROUND

Bronchiolitis obliterans (BO) is the leading cause of mortality beyond the first year after pediatric lung transplant, but the performance of an open lung biopsy is often required for diagnosis. Bronchiolitis obliterans syndrome (BOS) is a clinical diagnosis based on spirometric data that is the accepted standard for staging chronic allograft dysfunction.

METHODS

We determined the sensitivity, specificity, and positive and negative predictive values of BOS for predicting BO in children. A chart review was conducted on 139 open lung biopsies and 43 lung explants performed at our center from 1990 through June 2010 in pediatric recipients of lung transplants. Results were excluded from analysis if insufficient data existed to calculate a stable BOS stage before biopsy/explant.

RESULTS

The criteria for inclusion in the study were met by 67 open lung biopsies and 31 lung explants. The sensitivity, specificity, positive predictive value, and negative predictive value of BOS for predicting BO were 91.0%, 25.8%, 72.6%, and 57.1%.

CONCLUSIONS

We found that early declines in lung function are sensitive, but not specific, for BO. The low specificity of BOS for identifying BO illustrates the challenge facing clinicians in determining the etiology of pulmonary decline after lung transplant.

Colonization with small conidia Aspergillus species is associated with bronchiolitis obliterans syndrome: a two-center validation study

Aspergillus colonization after lung transplantation may increase the risk for bronchiolitis obliterans syndrome (BOS), a disease of small airways. We hypothesized that colonization with small conidia Aspergillus species would be associated with a greater risk of BOS, based upon an increased likelihood of deposition in small airways. We studied adult primary lung recipients from two large centers; 298 recipients at University of California, Los Angeles and 482 recipients at Duke University Medical Center. We grouped Aspergillus species by conidia diameter≤3.5 μm. We assessed the relationship of colonization with outcomes in Cox models. Pre-BOS colonization with small conidia Aspergillus species, but not large, was a risk factor for BOS (p=0.002, HR 1.44, 95% CI 1.14-1.82), along with acute rejection, single lung and Pseudomonas. Colonization with small conidia species also associated with risk of death (p=0.03, HR 1.30, 95% CI 1.03-1.64). Although other virulence traits besides conidia size may be important, we have demonstrated in two large independent cohorts that colonization with small conidia Aspergillus species increases the risk of BOS and death. Prospective evaluation of strategies to prevent Aspergillus colonization of small airways is warranted, with the goal of preserving lung allograft function as long as possible.

Potential functional and survival benefit of double over single lung transplantation for selected patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a frequent indication for lung transplantation (LTX) with pulmonary hypertension (PH) negatively affecting outcome. The optimal procedure type remains a debated topic. The aim of this study was to evaluate the impact of pretransplant PH in IPF patients. Single LTX (SLTX, n = 46) was the standard procedure type. Double LTX (DLTX, n = 30) was only performed in cases of relevant PH or additional suppurative lung disease. There was no significant difference for pretransplant clinical parameters. Preoperative mean pulmonary arterial pressure was significantly higher in DLTX recipients (22.7 +/- 0.8 mmHg vs. 35.9 +/- 1.8 mmHg, P < 0.001). After transplantation, 6-min-walk distance and BEST-FEV(1) were significantly higher for DLTX patients (6-MWD: 410 +/- 25 m vs. 498 +/- 23 m, P = 0.02; BEST-FEV(1): 71.2 +/- 3.0 (% pred) vs. 86.2 +/- 4.2 (% pred), P = 0.004). Double LTX recipients demonstrated a significantly better 1-year-, overall- and Bronchiolitis obliterans Syndrome (BOS)-free survival (P < 0.05). Cox regression analysis confirmed SLTX to be a significant predictor for death and BOS. Single LTX offers acceptable survival rates for IPF patients. Double LTX provides a significant benefit in selected recipients. Our data warrant further trials of SLTX versus DLTX stratifying for potential confounders including PH.

Acute cellular rejection is a risk factor for bronchiolitis obliterans syndrome independent of post-transplant baseline FEV1

BACKGROUND

Post-transplant baseline forced expiratory volume in 1 second (FEV(1)) constitutes a systematic bias in analyses of bronchiolitis obliterans syndrome (BOS). This retrospective study evaluates risk factors for BOS adjusting for the confounding of post-transplant baseline FEV(1).

METHODS

A multivariate survival and competing risk analysis of a large consecutive series of patients (n = 389) from a national center 1992 to 2004. Exclusion criteria were patients not surviving at least 3 months after transplantation (n = 39) and no available lung function measurements (n = 4).

RESULTS

The first maximum FEV(1) occurred at a median 183 days post-transplant. Freedom from BOS was 81%, 53%, 38% and 15%, and cumulative incidence of BOS was 18%, 43%, 57% and 77% at 1, 3, 5 and 10 years post-transplantation, respectively. Acute cellular rejection was independently associated with an increased cause-specific hazard of BOS (hazard ratio 1.4, confidence interval 1.1 to 1.8, p = 0.009). The absolute value of baseline FEV(1) was a significant confounder in all survival and competing risk analyses of BOS (p < 0.05).

CONCLUSION

Despite early diagnosis and prompt treatment, acute cellular rejection remains an independent risk factor for the development of BOS after adjusting for the confounding of post-transplant baseline FEV(1).