Bronchiolitis obliterans syndrome after single-lung transplantation: impact of time to onset on functional pattern and survival

Relationship of Exercise Capacity, Physical Function, and Frailty Measures With Clinical Outcomes and Healthcare Utilization in Lung Transplantation: A Scoping Review

Measures of exercise capacity, frailty, and physical function are commonly used in lung transplant candidates and recipients to evaluate their physical limitations and the effects of exercise training and to select candidates for transplantation. It is unclear how these measures are related to clinical outcomes and healthcare utilization before and after lung transplantation. The purpose of this scoping review was to describe how measures of exercise capacity, physical function, and frailty are related to pre- and posttransplant outcomes.

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.

Machine Learning Algorithms Utilizing Quantitative CT Features May Predict Eventual Onset of Bronchiolitis Obliterans Syndrome After Lung Transplantation

RATIONALE AND OBJECTIVES

Long-term survival after lung transplantation (LTx) is limited by bronchiolitis obliterans syndrome (BOS), defined as a sustained decline in forced expiratory volume in the first second (FEV₁) not explained by other causes. We assessed whether machine learning (ML) utilizing quantitative computed tomography (qCT) metrics can predict eventual development of BOS.

MATERIALS AND METHODS

Paired inspiratory-expiratory CT scans of 71 patients who underwent LTx were analyzed retrospectively (BOS [n = 41] versus non-BOS [n = 30]), using at least two different time points. The BOS cohort experienced a reduction in FEV₁ of >10% compared to baseline FEV₁ post LTx. Multifactor analysis correlated declining FEV₁ with qCT features linked to acute inflammation or BOS onset. Student t test and ML were applied on baseline qCT features to identify lung transplant patients at baseline that eventually developed BOS.

RESULTS

The FEV₁ decline in the BOS cohort correlated with an increase in the lung volume (P = .027) and in the central airway volume at functional residual capacity (P = .018), not observed in non-BOS patients, whereas the non-BOS cohort experienced a decrease in the central airway volume at total lung capacity with declining FEV₁ (P = .039). Twenty-three baseline qCT parameters could significantly distinguish between non-BOS patients and eventual BOS developers (P < .05), whereas no pulmonary function testing parameters could. Using ML methods (support vector machine), we could identify BOS developers at baseline with an accuracy of 85%, using only three qCT parameters.

CONCLUSIONS

ML utilizing qCT could discern distinct mechanisms driving FEV₁ decline in BOS and non-BOS LTx patients and predict eventual onset of BOS. This approach may become useful to optimize management of LTx patients.

Development of a Multivariate Prediction Model for Early-Onset Bronchiolitis Obliterans Syndrome and Restrictive Allograft Syndrome in Lung Transplantation

BACKGROUND

Chronic lung allograft dysfunction and its main phenotypes, bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS), are major causes of mortality after lung transplantation (LT). RAS and early-onset BOS, developing within 3 years after LT, are associated with particularly inferior clinical outcomes. Prediction models for early-onset BOS and RAS have not been previously described.

METHODS

LT recipients of the French and Swiss transplant cohorts were eligible for inclusion in the SysCLAD cohort if they were alive with at least 2 years of follow-up but less than 3 years, or if they died or were retransplanted at any time less than 3 years. These patients were assessed for early-onset BOS, RAS, or stable allograft function by an adjudication committee. Baseline characteristics, data on surgery, immunosuppression, and year-1 follow-up were collected. Prediction models for BOS and RAS were developed using multivariate logistic regression and multivariate multinomial analysis.

RESULTS

Among patients fulfilling the eligibility criteria, we identified 149 stable, 51 BOS, and 30 RAS subjects. The best prediction model for early-onset BOS and RAS included the underlying diagnosis, induction treatment, immunosuppression, and year-1 class II donor-specific antibodies (DSAs). Within this model, class II DSAs were associated with BOS and RAS, whereas pre-LT diagnoses of interstitial lung disease and chronic obstructive pulmonary disease were associated with RAS.

CONCLUSION

Although these findings need further validation, results indicate that specific baseline and year-1 parameters may serve as predictors of BOS or RAS by 3 years post-LT. Their identification may allow intervention or guide risk stratification, aiming for an individualized patient management approach.

An international ISHLT/ATS/ERS clinical practice guideline: diagnosis and management of bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS) is a major complication of lung transplantation that is associated with poor survival. The International Society for Heart and Lung Transplantation, American Thoracic Society, and European Respiratory Society convened a committee of international experts to describe and/or provide recommendations for 1) the definition of BOS, 2) the risk factors for developing BOS, 3) the diagnosis of BOS, and 4) the management and prevention of BOS. A pragmatic evidence synthesis was performed to identify all unique citations related to BOS published from 1980 through to March, 2013. The expert committee discussed the available research evidence upon which the updated definition of BOS, identified risk factors and recommendations are based. The committee followed the GRADE (Grading of Recommendation, Assessment, Development and Evaluation) approach to develop specific clinical recommendations. The term BOS should be used to describe a delayed allograft dysfunction with persistent decline in forced expiratory volume in 1 s that is not caused by other known and potentially reversible causes of post-transplant loss of lung function. The committee formulated specific recommendations about the use of systemic corticosteroids, cyclosporine, tacrolimus, azithromycin and about re-transplantation in patients with suspected and confirmed BOS. The diagnosis of BOS requires the careful exclusion of other post-transplant complications that can cause delayed lung allograft dysfunction, and several risk factors have been identified that have a significant association with the onset of BOS. Currently available therapies have not been proven to result in significant benefit in the prevention or treatment of BOS. Adequately designed and executed randomised controlled trials that properly measure and report all patient-important outcomes are needed to identify optimal therapies for established BOS and effective strategies for its prevention.

Time-dependent changes in the risk of death in pure bronchiolitis obliterans syndrome (BOS)

BACKGROUND

The timing of disease onset may affect the prognosis in chronic lung allograft dysfunction (CLAD). The relationship between the timing of disease onset and the prognosis of CLAD and its sub-types, bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS), was examined.

METHODS

Clinical records and pulmonary function data of 597 patients who underwent bilateral lung transplantation from 1996 to 2010 and survived for >3 months were examined.

RESULTS

Among 155 patients with a final diagnosis of BOS, patient survival after disease onset was significantly different according to disease-onset timing (BOS onset/post-BOS median survival: overall/1,438 days; <1 year/511 days; 1-2 years/1,199 days; 2-3 years/1,403 days; >3 years/did not reach median survival; p < 0.0001). The prognosis of RAS was generally poorer than that of BOS (overall post-RAS median survival, 377 days). Treating non-CLAD, CLAD, BOS, and RAS as time-dependent covariates, recipient sex-adjusted and age-adjusted Cox regression analysis demonstrated an overall mortality risk of BOS (reference: no CLAD) of 6.7 (95% confidence interval, 4.6-9.9). However, when patients survived 3 years without CLAD, the mortality risk of subsequent BOS was only 1.9 (95% confidence interval, 0.8-4.4) compared with no CLAD. The number of RAS patients was too small to obtain sufficient power to estimate time-dependent mortality risk.

CONCLUSION

Late-onset BOS showed a better prognosis than early-onset BOS. Studies that do not distinguish BOS from RAS may overestimate the mortality risk of BOS. Multicenter studies will be required to further elucidate risk factors toward the development of better management strategies for CLAD.

Bronchiolitis Obliterans Syndrome and Chronic Lung Allograft Dysfunction: Evolving Concepts and Nomenclature

Bronchiolitis obliterans syndrome (BOS) eventually occurs in the majority of lung transplant recipients who survive beyond 1 year, can greatly impair quality of life, and is, directly or indirectly, the major cause of delayed allograft dysfunction and recipient death. A number of associated events or conditions are strongly associated with the risk for developing BOS; these include acute rejection, gastroesophageal reflux, infections, and autoimmune reactions that can occur in the setting of alloimmune responses to the lung allograft as recipients are given intense immunosuppression to prevent allograft rejection. The term chronic lung allograft dysfunction (CLAD) is being increasingly used to refer to recipients with late allograft dysfunction that meets the spirometric criteria for the diagnosis of BOS, but clinicians should recognize that such dysfunction can occur for a variety of reasons other than BOS. The recently identified entity of restrictive allograft syndrome, which is now recognized as a relatively distinct phenotype of CLAD, has features that differentiate it from classic obstructive BOS. A number of other entities that can also significantly affect allograft function must also be considered when significant allograft dysfunction is encountered following lung transplantation.

Survival determinants in lung transplant patients with chronic allograft dysfunction

BACKGROUND

Chronic lung allograft dysfunction (CLAD) remains the leading cause of mortality after lung transplantation.

METHODS

In this retrospective single-center study, we aimed to identify different phenotypes of and risk factors for mortality after CLAD diagnosis using univariate and multivariate Cox proportional hazard survival regression analysis.

RESULTS

CLAD was diagnosed in 71 of 294 patients (24.2%) at 30.9±22.8 months after transplantation. Pulmonary function was obstructive in 51 (71.8%) of the CLAD patients, restrictive in 20 (28.2%) patients, of whom 17 had persistent parenchymal infiltrates on pulmonary computer tomography (CAT) scan. In univariate analysis, previous development of neutrophilic reversible allograft dysfunction (NRAD, P=0.012) and a restrictive pulmonary function (P=0.0024) were associated with a worse survival, whereas there was a strong trend for early development of CLAD and persistent parenchymal infiltrates on CAT scan (P=0.067 and 0.056, respectively). In multivariate analysis, early development of CLAD (P=0.0067), previous development of NRAD (P=0.0016), and a restrictive pulmonary function pattern (P=0.0005) or persistent parenchymal infiltrates on CAT scan (P=0.0043) remained significant.

CONCLUSION

Although most CLAD patients develop an obstructive pulmonary function, 28% develop a restrictive pulmonary function, compatible with the recently defined restrictive allograft syndrome phenotype. Early-onset CLAD, previous development of NRAD, and the development of restrictive allograft syndrome are associated with worse survival after CLAD has been diagnosed.

Bronchiolitis obliterans syndrome occurs earlier in the post-lung allocation score era

OBJECTIVES

In 2005, the time-based waiting list for lung transplantation was replaced by an illness/benefit lung allocation score (LAS). Although short-term outcomes after transplantation have been reported to be similar before and after the new system, little is known about long-term results. The objective of this study was to evaluate the impact of LAS on the development of bronchiolitis obliterans syndrome as well as on overall 3-year and bronchiolitis obliterans syndrome-related survival.

METHODS

Data obtained from the United Network for Organ Sharing were used to review 8091 patients who underwent lung transplantation from 2002 to 2008. Patients were stratified according to time of transplantation into those treated before initiation of the LAS (pre-LAS group, January 2002-April 2005, n = 3729) and those treated after implementation of the score (post-LAS group, May 2005-May 2008, n = 4362). Overall, 3-year survivals for patient groups were compared using a univariate analysis, Cox proportional hazards model to generate a relative risk, and Kaplan-Meier curve analyses.

RESULTS

During the 3-year follow-up period, bronchiolitis obliterans syndrome developed in 22% of lung transplant recipients (n = 1801). Although the incidence of postoperative bronchiolitis obliterans syndrome development was similar between groups, post-LAS patients incurred fewer bronchiolitis obliterans syndrome-free days (609 ± 7.5 vs 682 ± 9; P <.0001; log-rank test P = .0108) than did pre-LAS patients. Overall 3-year survival was lower in post-LAS patients and approached statistical significance (P = .05). Similarly, bronchiolitis obliterans syndrome-related survival was worse for patients in the post-LAS group (log-rank test P = .01).

CONCLUSIONS

In the current LAS era, lung transplant recipients have significantly fewer bronchiolitis obliterans syndrome-free days after 3-year follow-up. Compared with the pre-LAS population, overall and bronchiolitis obliterans syndrome-related survival appears worse in the post-LAS era. Limitation of known risk factors for development of bronchiolitis obliterans syndrome-may prove even more important in this patient population.

Survival after bronchiolitis obliterans syndrome among bilateral lung transplant recipients

RATIONALE

Despite the importance of bronchiolitis obliterans syndrome (BOS) in lung transplantation, little is known regarding the factors that influence survival after the onset of this condition, particularly among bilateral transplant recipients.

OBJECTIVES

To identify factors that influence survival after the onset of BOS among bilateral lung transplant recipients.

METHODS

The effect of demographic or clinical factors, occurring before BOS, upon survival after the onset of BOS was studied in 95 bilateral lung transplant recipient using Cox proportional hazards models.

MEASUREMENTS AND MAIN RESULTS

Although many factors, including prior acute rejection or rejection treatments, were not associated with survival after BOS, BOS onset within 2 years of transplantation (early-onset BOS), or BOS onset grade of 2 or 3 (high-grade onset) were predictive of significantly worse survival (early onset P = 0.04; hazard ratio, 1.84; 95% confidence interval, 1.03-3.29; high-grade onset P = 0.003; hazard ratio, 2.40; 95% confidence interval, 1.34-4.32). The effects of both early onset and high-grade onset on survival persisted in multivariable analysis and after adjustment for concurrent treatments. Results suggested an interaction might exist between early onset and high-grade onset. In particular, high-grade onset of BOS, regardless of its timing after transplant, is associated with a very poor prognosis.

CONCLUSIONS

The course of BOS after bilateral lung transplantation is variable. Distinct patterns of survival after BOS are evident and related to timing or severity of onset. Further characterization of these subgroups should provide a more rational basis from which to design, stratify, and assess response in future BOS treatment trials.

Course of Illness after the Onset of Chronic Rejection in Lung Transplant Recipients

Background Despite the overall negative impact of chronic rejection on quality of life and survival after lung transplant, the specific clinical indicators of deterioration have not been identified.

Objectives To describe the course of illness after the onset of chronic rejection, including demographic and transplant variables, morbidity, mortality, health resource utilization, and end-of-life care, and to identify clinical indicators of deterioration in health and limited survival after the onset of chronic rejection.

Methods The medical records of 311 recipients of lung transplants between 1998 and 2004 were reviewed retrospectively to identify 60 recipients who experienced chronic rejection.

Results Median survival after chronic rejection was 31.34 months. Time to rejection (mean, 26.05 months; SD, 16.85) was significantly correlated with overall survival without need of a retransplant (r = 0.64; P &lt; .001). The earlier the onset of chronic rejection or the need for oxygen at home, the shorter was the period of survival after chronic rejection and the more frequent were hospital and intensive care unit admissions and prolonged stays. Of the 26 recipients who died, 65% died at the transplant center, and all but 1 died in the intensive care unit; 3 died after multiple attempts of cardiopulmonary resuscitation; life support was ultimately withdrawn in 69%.

Conclusions Lung transplant recipients who experience chronic graft rejection have high rates of morbidity, mortality, and health resource utilization; however, the course of illness after chronic rejection is highly variable.

Challenges in pulmonary fibrosis. 2: Bronchiolocentric fibrosis

Bronchiolocentric fibrosis is essentially represented by the pathological pattern of constrictive fibrotic bronchiolitis obliterans. The corresponding clinical condition (obliterative bronchiolitis) is characterised by dyspnoea, airflow obstruction at lung function testing and air trapping with characteristic mosaic features on expiratory high resolution CT scans. Bronchiolitis obliterans may result from many causes including acute diffuse bronchiolar damage after inhalation of toxic gases or fumes, alloimmune chronic processes after lung or haematopoietic stem cell transplantation, or connective tissue disease (especially rheumatoid arthritis). Airway-centred interstitial fibrosis and bronchiolar metaplasia are other features of bronchiolocentric fibrosis.

Long-term Survival After Lung Transplantation Depends on Development and Severity of Bronchiolitis Obliterans Syndrome

BACKGROUND

The objectives of this study were to describe the natural history of bronchiolitis obliterans syndrome (BOS) in a large consecutive series of patients from a national center in accordance with the most recent grading criteria, and to examine the prognosis with respect to onset and severity of BOS.

METHODS

All patients receiving a cadaveric lung transplant between 1992 and 2004 were included in the study (n = 389). Exclusion criteria were patients not surviving at least 3 months after transplantation (n = 39) and lack of available lung function measurements (n = 4).

RESULTS

The 1-, 3-, 5- and 10-year actuarial survival rates for the entire series were 81%, 67%, 60% and 36%, respectively. The 1-, 3-, 5- and 10-year actuarial freedom from BOS Grade > or = 1 was 81%, 53%, 38% and 15%, respectively. A Cox regression model with BOS grade as a time-dependent covariate was performed in a sub-group of patients surviving at least 3 years (n = 237). Both progression from BOS Grade 1 to 2 and from BOS Grade 2 to 3 were associated with a significant increase in mortality: hazard ratio (HR) = 3.1 (confidence interval [CI] 1.2 to 7.9) and HR = 2.9 (CI 1.6 to 5.3), respectively. The addition of a non-time-dependent covariate to signify early (within 18 months of transplantation) or late (after 18 months) development of BOS was not significant (p = 0.5).

CONCLUSIONS

The development and progression of chronic allograft rejection after lung transplantation (BOS Grades 2 and 3) is associated with a 3-fold increase in the risk of death at each stage, irrespective of whether BOS developed early or late.

Course of FEV(1) after onset of bronchiolitis obliterans syndrome in lung transplant recipients

RATIONALE

Bronchiolitis obliterans syndrome (BOS), defined by loss of lung function, develops in the majority of lung transplant recipients. However, there is a paucity of information on the subsequent course of lung function in these patients.

OBJECTIVES

To characterize the course of FEV(1) over time after development of BOS and to determine the predictors that influence the rate of functional decline of FEV(1).

METHODS

FEV(1)% predicted (FEV(1)%pred) trajectories were studied in 111 lung transplant recipients with BOS by multivariate, linear, mixed-effects statistical models.

MEASUREMENTS AND MAIN RESULTS

FEV(1)%pred varied over time after BOS onset, with the steepest decline typically seen in the first 6 months (12% decline; p < 0.0001). Bilateral lung transplant recipients had significantly higher FEV(1)%pred at BOS diagnosis (71 vs. 47%; p < 0.0001) and at 24 months after BOS onset (58 vs. 41%; p = 0.0001). Female gender and pretransplant diagnosis of idiopathic pulmonary fibrosis were associated with a steeper decline in FEV(1)%pred in the first 6 months after BOS diagnosis (p = 0.02 and 0.04, respectively). A fall in FEV(1) greater than 20% in the 6 months preceding BOS (termed "rapid onset") was associated with shorter time to BOS onset (p = 0.01), lower FEV(1)%pred at BOS onset (p < 0.0001), steeper decline in the first 6 months (p = 0.03), and lower FEV(1)%pred at 2 years after onset (p = 0.0002).

CONCLUSIONS

Rapid onset of BOS, female gender, pretransplant diagnosis of idiopathic pulmonary fibrosis, and single-lung transplantation are associated with worse pulmonary function after BOS onset.

Bronchiolitis obliterans following lung transplantation

Bronchiolitis obliterans syndrome (BOS) is the main and late chronic complication after lung transplantation. It remains a major impediment to long-term outcome. Unfortunately, the survival rate of lung transplant recipients lags behind that of other organ transplant recipients, and BOS accounts for more than 30% of all mortality after the third year following lung transplantation. Most recent studies suggest that immune injury is the main pathogenic event in small airway obliteration and the development of BOS. Early detection of BOS is possible as well as essential because prompt initiation of treatment may halt the progress of the disease and the development of chronic graft failure. Current treatment of BOS is disappointing despite advances in surgical techniques and improvements in immunosuppressive therapies. Therefore, a clear understanding of the pathogenesis of BOS plays a major role in the search for new and effective therapeutic strategies for better long-term survival and quality of life after lung transplantation.

Pulmonary complications of solid organ and hematopoietic stem cell transplantation

The ability to successfully transplant solid organs and hematopoietic stem cells represents one of the landmark medical achievements of the twentieth century. Solid organ transplantation has emerged as the standard of care for select patients with severe vital organ dysfunction and hematopoietic stem cell transplantation has become an important treatment option for patients with a wide spectrum of nonmalignant and malignant hematologic disorders, genetic disorders, and solid tumors. Although advances in surgical techniques, immunosuppressive management, and prophylaxis and treatment of infectious diseases have made long-term survival an achievable goal, transplant recipients remain at high risk for developing a myriad of serious and often life-threatening complications. Paramount among these are pulmonary complications, which arise as a consequence of the immunosuppressed status of the recipient as well as from such factors as the initial surgical insult of organ transplantation, the chemotherapy and radiation conditioning regimens that precede hematopoietic stem cell transplantation, and alloimmune mechanisms mediating host-versus-graft and graft-versus-host responses. As the population of transplant recipients continues to grow and as their care progressively shifts from the university hospital to the community setting, knowledge of the pulmonary complications of transplantation is increasingly germane to the contemporary practice of pulmonary medicine.

[Bronchiolitis with airflow obstruction in adults]

PURPOSE

The purpose of this paper is twofold: to describe the clinical and anatomical characteristics of bronchiolitis associated with airflow obstruction in adults; to present through a clinical approach, a classification of the main aetiologies or pathological frames associated with that entity.

KEY POINTS

The constrictive bronchiolitis type is the most frequently encountered. On clinical grounds, cough, crackles, and a progressive dyspnea develop usually within a few weeks. Radiological signs of bronchiolar abnormalities are best visualized on high resolution expiratory CT scan. The decrease in maximal airflows and oxygen tension is of limited amplitude and poorly reversible with bronchodilators. Diagnosis is easily performed when a causative event, or the clinical context, can be delineated: inhalation of toxic fumes, diffuse bronchiectasis, rheumatoid arthritis, lung or bone marrow transplantation. Delayed formation of bronchiectasis in the central airways is common. The treatment is not standardized; corticosteroids are usually prescribed as a first line therapy; the benefit of the addition of, or substitution with immunosuppressive drugs has not been adequately evaluated, but is, on the mean, of limited amplitude.

PERSPECTIVES

Recent advances in the identification of inhaled agents toxic for the distal airways help in establishing appropriate measures of prevention. When the aetiology of the bronchiolitis cannot be suspected, extensive search of a causative agent should be performed, including microbial and mineral analysis of bronchoalveolar products. Negative results should lead to perform a surgical lung biopsy. The study of chronic rejection processes in animal models of lung transplantation, the identification of inhibitory factors of bronchiolar fibrogenesis, and the efficacy of some anti-cytokines on inflammatory processes could result in new therapeutic approaches.