Lung transplantation and gender effects on survival of recipients with cystic fibrosis

Sex disparities in cystic fibrosis in the era of highly effective modulator treatment

Cystic fibrosis (CF) is a genetic disorder characterized by progressive lung disease and extra-pulmonary manifestations with notable sex disparities in disease outcomes. In this review we summarize the underlying mechanisms driving this sex disparity, with a particular focus on the role of sex hormones on CF lung disease pathophysiology. We explore how the introduction of highly effective modulator therapies (HEMT) may impact sex differences in outcomes and assess whether they have the potential to close the sex gap. While treatment with HEMT has led to better outcomes in the CF population as a whole, females with CF continue to experience worse pulmonary morbidity than males. There is a need for continued research in this area, particularly into the influence and therapeutic potential of sex hormones.

Perioperative Considerations Regarding Sex in Solid Organ Transplantation

Sex plays a pivotal role in all stages of the organ transplant process. In the preoperative phase, sex can affect being listed or considered for a transplant, and sex/size matching of organs is necessary for some organ transplants, thereby affecting organ availability. In the postoperative period, sex has a profound impact on complications as well as graft survival. Sex-related differences in organ transplantation are likely multifactorial related to biological and social characteristics. This article provides an overview of the impact of sex on various types of solid organ transplant, including kidney, pancreas, liver, lung, and heart transplants.

The effect of donor-recipient sex matches on lung transplant survival: An analysis of the United Network for Organ Sharing database

Objective

To investigate the impact of donor-recipient (DR) sex matches on survival after lung transplantation while controlling for size difference in the United Network of Organ Sharing (UNOS) database.

Methods

We performed a retrospective study of 27,423 lung transplant recipients who were reported in the UNOS database (January 2005-March 2020). Patients were divided into groups based on their respective DR sex match: male to male (MM), male to female (MF), female to female, (FF), and female to male (FM). Kaplan-Meier curve and Cox regression with log-rank tests were used to assess 1-, 3-, 5-, and 10-year survival. We also modeled survival for each group after controlling for size-related variables via the Cox regression.

Results

Kaplan-Meier curves showed overall significance at 1-, 3-, 5-, and 10-year end points (P < .0001). Estimated median survival time based on Kaplan-Meier analysis were 6.41 ± 0.15, 6.13 ± 0.18, 5.86 ± 0.10, and 5.37 ± 0.17 years for FF, MF, MM, and FM, respectively (P < .0001). After we controlled for size differences, FF had statistically significantly longer 5- and 10-year survival than all other cohorts. MF also had statistically significantly longer 5- and 10-year survival than FM.

Conclusions

When variables associated with size were controlled for, FF had improved survival than other DR groups. A female recipient may experience longer survival with a female donor's lungs versus a male donor's lungs of similar size.

Sex differences in outcomes of people with cystic fibrosis treated with elexacaftor/tezacaftor/ivacaftor

BACKGROUND

There is a well described sex-disparity in outcomes of individuals with cystic fibrosis (CF), with females faring worse than males. Given the dramatic improvement in overall health of people with CF using CF transmembrane conductance regulator (CFTR) modulator therapy, elexacaftor/tezacaftor/ivacaftor (ETI), the sex-disparity in CF warrants re-examination.

METHODS

We evaluated the effects of ETI use by sex prior to versus after initiation of ETI by pulmonary exacerbations (PEx), percent predicted forced expiratory volume in one second (ppFEV1), presence of Pseudomonas aeruginosa in sputum cultures, and body mass index (BMI). We used univariate and multivariable longitudinal regression adjusting for key confounders, such as age, race, CFTR modulator taken prior to ETI and baseline ppFEV1.

RESULTS

We included 251 individuals started on ETI between January 2014 to September 2022. We collected data for a mean of 5.45 years pre-ETI and 2.38 years post-ETI. We found the adjusted presence of PEx decreased more in males than females pre- to post-ETI with the odds of having a PEx in males being 0.57 (43% reduction) versus females 0.75 (25% reduction) (p = 0.049). We found no statistical difference by sex for ppFEV1, presence of Pseudomonas aeruginosa or BMI pre- to post-ETI by sex.

CONCLUSION

After treatment with ETI, there was a greater decline in PEx in males versus females. Long-term impact of ETI by sex is still unknown, but we will need to seek ways to effectively tailor care for individuals with CF and consider pharmacokinetic studies of ETI comparing males to females.

Conditional Survival in Lung Transplantation: An Organ Procurement and Transplantation Network Database Analysis

Lung transplantation survival estimates are traditionally reported as fixed 1-, 5-, and 10-year mortality rates. Alternatively, this study aims to demonstrate how conditional survival models can provide useful prognostic information tailored to the time a recipient has already survived from the date of transplantation. Recipient data was obtained from the Organ Procurement and Transplantation Network database. Data from 24,820 adult recipients over age 18 who received a lung transplant between 2002 and 2017 were included in the study. Five-year observed conditional survival estimates were calculated by recipient age, sex, race, transplant indication, transplant type ( i.e. , single or double), and renal function at the time of transplantation. Significant variability exists in conditional survival following lung transplantation. Each specific recipient characteristic significantly impacted conditional survival during at least one time point in the first 5 years. Younger age and double lung transplantation were the two most positive predictors of improved conditional survival consistently throughout the 5-year study period. Conditional survival in lung transplantation recipients changes over time and across recipient characteristics. Hazards of mortality are not fixed and need to be dynamically evaluated as a function of time. Conditional survival calculations can provide more accurate prognostic predictions than unconditional survival estimates.

2022 Update of indications and contraindications for lung transplantation in France

Lung transplantation (LTx) is a steadily expanding field. The considerable developments have been driven over the years by indefatigable work conducted at LTx centers to improve donor and recipient selection, combined with multifaceted efforts to overcome challenges raised by the surgical procedure, perioperative care, and long-term medical complications. One consequence has been a pruning away of contraindications over time, which has, in some ways, complicated the patient selection process. The Francophone Pulmonology Society (Société de Pneumology de Langue Française, SPLF) set up a task force to produce up-to-date working guidelines designed to assist pulmonologists in managing end-stage respiratory insufficiency, determining which patients may be eligible for LTx, and appropriately timing LTx-center referral. The task force examined the most recent literature and evaluated the risk factors that limit patient survival after LTx. Ideally, the objectives of LTx are to prolong life while also improving quality of life. The guidelines developed by the task force apply to a limited resource and are consistent with the ethical principles described below.

Cystic Fibrosis: Highly Effective Targeted Therapeutics and the Impact on Sex and Racial Disparities

People with Cystic Fibrosis (CF) are living longer and healthier lives due in part to new therapies, called Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) modulators. However, disparities in outcomes still exist, with females demonstrating a shorter life expectancy than males; this is opposed to the typical female versus male life expectancy in the general United States population. In addition, minority populations such as those of Hispanic ethnicity and African Americans are less frequently eligible for these new CFTR modulators. The mechanisms driving this difference and the relative contribution of CFTR to the etiology are not yet elucidated.

Survival difference between high-risk and low-risk CFTR genotypes after lung transplant

BACKGROUND

While cystic fibrosis transmembrane conductance regulator (CFTR) genotypes are associated with clinical outcomes in cystic fibrosis patients, it is unknown if genotype impacts lung transplant outcomes. We sought to compare lung transplant survival and time to bronchiolitis obliterans syndrome (BOS) between high-risk, low-risk, and not yet classified CFTR genotypes.

METHODS

We used merged data from the Organ Procurement and Transplantation Network (2005-2017) and United States Cystic Fibrosis Foundation Patient Registry (2005-2016). Cox Proportional Hazards models compared graft failure after lung transplant and time to BOS among high-risk, low-risk, and not yet classified risk CFTR genotype classes.

RESULTS

Among 1,830 cystic fibrosis lung transplant recipients, median survival for those with low-risk, high-risk, and not yet classified genotype was 9.83, 6.25, and 5.75 years, respectively. Adjusted Cox models showed recipients with a low-risk genotype had 39% lower risk of death or re-transplant compared to those with high-risk genotype (adjusted HR 0.61, 95% CI = 0.40, 0.91). A subset of 1,585 lung transplant recipients were included in the BOS subgroup analysis. Adjusted analyses showed no significant difference of developing BOS among high-risk, low-risk, or not yet classified genotypes.

CONCLUSIONS

Lung transplant recipients with low-risk CFTR genotype have better survival after transplant compared to recipients with high-risk or not yet classified genotypes. Given these differences, future studies evaluating the mechanism by which CFTR genotype affects post-transplant survival could identify potential targets for intervention.

The role of donor-recipient gender matching in lung transplantation: a systematic review

INTRODUCTION

Donor to recipient (D-R) matching in lung transplantation (LTx) is firstly directed by blood group (identity or compatibility), immunological status and morphological criteria. Sex matching is ignored and impact on outcome less investigated.

EVIDENCE ACQUISITION

Systematic review of English literature using PubMed (1990-2019) was performed to evaluate the potential role of D-R matching in determining long-term outcome in patients after LTx. Search terms included (LTx) AND (sex) OR (gender) OR (matching) OR (mismatch) OR (donor characteristics) and were restricted to articles' title. Only articles directly reporting LTx survival outcome according to gender match/mismatch and D-R gender combination in LTx were included. Two authors independently extracted articles using predefined data fields, including study quality indicators. MOOSE Guidelines for Meta-Analyses and Systematic Reviews of Observational Studies applied.

EVIDENCE SYNTHESIS

Nine articles were analyzed and included into this study. All studies analyzed the effect of the different D-R gender combinations on survival while seven of them investigated exclusively the role of sex matching on LTx outcome. In this latter group two out of seven showed a trend towards an overall survival advantage for sex matching LTx combination. The worst survival results were reported for F to M gender combination in 3 studies and for M to F gender combination by 1 study. No differences were reported in remaining 4 studies.

CONCLUSIONS

This systematic review suggests that sex matching and several gender combinations could play a role in determining overall survival rate after LTx. Data deriving from unbiased studies supported that matching female-female (F-F) and male-male (M-M) could improve LTx outcome while FD-MR combination should be avoided. Unfortunately, a good part of the analyzed data are affected by bias due to confounding factors. Up-to-date immunological, hormonal and morphological factors could explain the gender-based difference in LTx outcome. Further investigations should clarify their role and importance to define the effects of gender combinations on survival.

Longitudinal assessment of renal function after lung transplantation for cystic fibrosis: transition from post-operative acute kidney injury to acute kidney disease and chronic kidney failure

INTRODUCTION

The clinical trajectory of post-operative acute kidney injury (AKI) following lung transplantation for cystic fibrosis is unknown.

METHODS

Incidence and risk factors for post-operative AKI, acute kidney disease (AKD) and chronic kidney disease (CKD) were retrospectively analyzed in cystic fibrosis patients undergoing lung transplantation. Logistic regressions, Chi-square, Cuzick rank tests, and Cox-proportional hazard models were used.

RESULTS

Eighty-three patients were included. Creatinine peaked 3[2-4] days after transplantation, with 15(18%), 15(18%), and 20(24%) patients having post-operative AKI stages 1, 2, and 3, while 15(18%), 19(23%) and 10(12%) developed AKD stage 1, stage 2 and 3, respectively. Higher AKI stage was associated with worsening AKD (p = 0.009) and CKD (p = 0.015) stages. Of the 50 patients with AKI, 32(66%) transitioned to AKD stage > 0, and then 27 (56%) to CKD stage > 1. Female sex, extracorporeal membrane oxygenation support as a bridge to lung transplant and at the end of the surgery, the use of intraoperative blood components, and cold-ischemia time were associated with increased risk of post-operative AKI and AKD. Higher AKI stage prolonged invasive mechanical ventilation (p = 0.0001), ICU stay (p = 0.0001), and hospital stay (p = 0.0001), and increased the incidence of primary graft dysfunction (p = 0.035). Both AKI and AKD stages > 2 worsened long-term survival with risk ratios of 3.71 (1.34-10.2), p = 0.0131 and 2.65(1.02-6.87), p = 0.0443, respectively.

DISCUSSION

AKI is frequent in cystic fibrosis patients undergoing lung transplantation, it often evolves to AKD and to chronic kidney disease, thereby worsening short- and long-term outcomes.

A shifting landscape: Practice patterns and outcomes of cystic fibrosis and non-cystic fibrosis pediatric lung transplantation

BACKGROUND

New drugs may further decrease the need for lung transplant (LTx) in pediatric patients with cystic fibrosis (CF), but few studies highlight pediatric non-CF LTx characteristics and outcomes.

METHODS

The ISHLT registry was used to report morbidity, graft failure, and survival for primary pediatric (<18 years) LTx performed 1990-2017. Recipient/donor characteristics and long-term outcomes were analyzed for CF and non-CF recipients. Survival was assessed using Kaplan-Meier curves.

RESULTS

Of 2232 primary LTx, (43% in males), 918 (41%) were performed for non-CF indications; most commonly pulmonary hypertension (43%). Non-CF patients were younger (median age 11 vs. 15, p < .001), and more frequently on inotropes and/or extracorporeal membrane oxygenation (15% vs. 2.4%, p < .001) at transplant, compared to CF recipients. In-hospital major complications more commonly affected CF LTx recipients (57% vs. 48%, p = .003), but 30-day mortality was higher in the non-CF group (9% non-CF vs. 5% CF, p < .001). One-, five-, and ten-year mortality was 18%, 50%, and 65% for CF recipients, respectively, and 21%, 45%, and 58% for non-CF recipients (p = .01 at 10 years). Five-year survival was significantly better for non-CF females versus CF females (56% vs. 48%, p = .013), but was similar between groups for males (55% vs. 54%, p = .305). While age was a late outcomes risk factor, pulmonary hypertension and later transplants eras were protective.

CONCLUSIONS

Early mortality is higher and late mortality is lower in non-CF LTx. Current non-CF LTx outcomes leave room for improvement. Further study is needed to evaluate the effects of center volume and pediatric-specific experience on outcomes.

Dependent lesion positioning at CT-guided lung biopsy to reduce risk of pneumothorax

OBJECTIVES

To evaluate the impact of patient positioning during CT-guided lung biopsy on patients' outcomes.

METHODS

In this retrospective, IRB-approved, HIPAA-compliant study, consecutive CT-guided lung biopsies performed on 5/1/2015-12/26/2017 were included. Correlation between incidence of pneumothorax, chest tube placement, pulmonary bleeding with patient, and procedure characteristics was evaluated. Lesion-trachea-table angle (LTTA) was defined as an angle between the lesion, trachea, and horizontal line parallel to the table. Lesion above trachea has a positive LTTA. Univariate and multivariate logistic regression analysis was performed.

RESULTS

A total of 423 biopsies in 409 patients (68 ± 11 years, 231/409, 56% female) were included in the study. Pneumothorax occurred in 83/423 (20%) biopsies with chest tube placed in 11/423 (3%) biopsies. Perilesional bleeding occurred in 194/423 (46%) biopsies and hemoptysis in 20/423 (5%) biopsies. Univariate analysis showed an association of pneumothorax with smaller lesions (p = 0.05), positive LTTA (p = 0.002), and lesions not attached to pleura (p = 0.026) with multivariate analysis showing lesion size and LTTA to be independent risk factors. Univariate analysis showed an association of increased pulmonary bleeding with smaller lesions (p < 0.001), no attachment to the pleura (p < 0.001), needle throw < 16 mm (p = 0.05), and a longer needle path (p < 0.001). Multivariate analysis showed lesion size, a longer needle path, and lesions not attached to the pleura to be independently associated with perilesional bleeding. Risk factors for hemoptysis were longer needle path (p = 0.002), no attachment to the pleura (p = 0.03), and female sex (p = 0.04).

CONCLUSIONS

Interventional radiologists can reduce the pneumothorax risk during the CT-guided biopsy by positioning the biopsy site below the trachea.

KEY POINTS

• Positioning patient with lesion to be below the trachea for the CT-guided lung biopsy results in lower rate of pneumothorax, as compared with the lesion above the trachea. • Positioning patient with lesion to be below the trachea for the CT-guided lung biopsy does not affect rate of procedure-associated pulmonary hemorrhage or hemoptysis.

Review 1: Lung transplant-from donor selection to graft preparation

For various end-stage lung diseases, lung transplantation remains one of the only viable treatment options. While the demand for lung transplantation has steadily risen over the last few decades, the availability of donor grafts is limited, which have resulted in progressively longer waiting lists. In the early years of lung transplantation, only the 'ideal' donor grafts are considered for transplantation. Due to the donor shortages, there is ongoing discussion about the safe use of 'suboptimal' grafts to expand the donor pool. In this review, we will discuss the considerations around donor selection, donor-recipient matching, graft preparation and graft optimisation.

Perioperative Considerations Regarding Sex in Solid Organ Transplantation

Sex plays a role in all stages of the organ transplant process, including listing, sex/size matching of organs, complications, graft survival, and mortality. Sex-related differences in organ transplantation are likely multifactorial related to biological and social characteristics. More information is needed to determine how sex-related differences can lead to improved outcomes for future donors and recipients of solid organs. This article provides an overview on the impact of sex on various types of solid organ transplant, including kidney, pancreas, liver, lung, and heart transplants.

Female Sex and Gender in Lung/Sleep Health and Disease. Increased Understanding of Basic Biological, Pathophysiological, and Behavioral Mechanisms Leading to Better Health for Female Patients with Lung Disease

Female sex/gender is an undercharacterized variable in studies related to lung development and disease. Notwithstanding, many aspects of lung and sleep biology and pathobiology are impacted by female sex and female reproductive transitions. These may manifest as differential gene expression or peculiar organ development. Some conditions are more prevalent in women, such as asthma and insomnia, or, in the case of lymphangioleiomyomatosis, are seen almost exclusively in women. In other diseases, presentation differs, such as the higher frequency of exacerbations experienced by women with chronic obstructive pulmonary disease or greater cardiac morbidity among women with sleep-disordered breathing. Recent advances in -omics and behavioral science provide an opportunity to specifically address sex-based differences and explore research needs and opportunities that will elucidate biochemical pathways, thus enabling more targeted/personalized therapies. To explore the status of and opportunities for research in this area, the NHLBI, in partnership with the NIH Office of Research on Women's Health and the Office of Rare Diseases Research, convened a workshop of investigators in Bethesda, Maryland on September 18 and 19, 2017. At the workshop, the participants reviewed the current understanding of the biological, behavioral, and clinical implications of female sex and gender on lung and sleep health and disease, and formulated recommendations that address research gaps, with a view to achieving better health outcomes through more precise management of female patients with nonneoplastic lung disease. This report summarizes those discussions.

Lack of association of Aspergillus colonization with the development of bronchiolitis obliterans syndrome in lung transplant recipients: An international cohort study

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is a major limitation in the long-term survival of lung transplant recipients (LTRs). However, the risk factors in the development of BOS remain undetermined. We conducted an international cohort study of LTRs to assess whether Aspergillus colonization with large or small conidia is a risk factor for the development of BOS.

METHODS

Consecutive LTRs from January 2005 to December 2008 were evaluated. Rates of BOS and associated risk factors were recorded at 4 years. International Society of Heart and Lung Transplantation criteria were used to define fungal and other infections. A Cox proportional-hazards-model was constructed to assess the association between Aspergillus colonization and the development of BOS controlling for confounders.

RESULTS

A total of 747 LTRs were included. The cumulative incidence of BOS at 4 years after transplant was 33% (250 of 747). Additionally, 22% of LTRs experienced Aspergillus colonization after transplantation. Aspergillus colonization with either large (hazard ratio [HR] = 0.6, 95% confidence interval [CI] = 0.3-1.2, p = 0.12) or small conidia (HR = 0.9, 95% CI = 0.6-1.4, p = 0.74) was not associated with the development of BOS. Factors associated with increased risk of development of BOS were the male gender (HR = 1.4, 95% CI = 1.1-1.8, p = 0.02) and episodes of acute rejection (1-2 episodes, HR = 1.5, 95% CI = 1.1-2.1, p = 0.014; 3-4 episodes, HR = 1.6, 95% CI = 1.0-2.6, p = 0.036; >4 episodes, HR = 2.2, 95% CI = 1.1-4.3, p = 0.02), whereas tacrolimus use was associated with reduced risk of BOS (HR = 0.6, 95% CI = 0.5-0.9, p = 0.007).

CONCLUSIONS

We conclude from this large multicenter cohort of lung transplant patients, that Aspergillus colonization with large or small conidia did not show an association with the development of BOS.

Lung transplant referral for individuals with cystic fibrosis: Cystic Fibrosis Foundation consensus guidelines

OBJECTIVE

Provide recommendations to the cystic fibrosis (CF) community to facilitate timely referral for lung transplantation for individuals with CF.

METHODS

The CF Foundation organized a multidisciplinary committee to develop CF Lung Transplant Referral Consensus Guidelines. Three workgroups were formed: timing for transplant referral; modifiable barriers to transplant; and transition to transplant care. A focus group of lung transplant recipients with CF and spouses of CF recipients informed guideline development.

RESULTS

The committee formulated 21 recommendation statements based on literature review, committee member practices, focus group insights, and in response to public comment. Critical approaches to optimizing access to lung transplant include early discussion of this treatment option, assessment for modifiable barriers to transplant, and open communication between the CF and lung transplant centers.

CONCLUSIONS

These guidelines will help CF providers counsel their patients and may reduce the number of individuals with CF who die without consideration for lung transplant.

Bronchiolitis obliterans syndrome-free survival after lung transplantation: An International Society for Heart and Lung Transplantation Thoracic Transplant Registry analysis

BACKGROUND

Lung transplant (LTx) recipients have low long-term survival and a high incidence of bronchiolitis obliterans syndrome (BOS). However, few long-term, multicenter, and precise estimates of BOS-free survival (a composite outcome of death or BOS) incidence exist.

METHODS

This retrospective cohort study of primary LTx recipients (1994-2011) reported to the International Society of Heart and Lung Transplantation Thoracic Transplant Registry assessed outcomes through 2012. For the composite primary outcome of BOS-free survival, we used Kaplan-Meier survival and Cox proportional hazards regression, censoring for loss to follow-up, end of study, and re-LTx. Although standard Thoracic Transplant Registry analyses censor at the last consecutive annual complete BOS status report, our analyses allowed for partially missing BOS data.

RESULTS

Due to BOS reporting standards, 99.1% of the cohort received LTx in North America. During 79,896 person-years of follow-up, single LTx (6,599 of 15,268 [43%]) and bilateral LTx (8,699 of 15,268 [57%]) recipients had a median BOS-free survival of 3.16 years (95% confidence interval [CI], 2.99-3.30 years) and 3.58 years (95% CI, 3.53-3.72 years), respectively. Almost 90% of the single and bilateral LTx recipients developed the composite outcome within 10 years of transplantation. Standard Registry analyses "overestimated" median BOS-free survival by 0.42 years and "underestimated" the median survival after BOS by about a half-year for both single and bilateral LTx (p < 0.05).

CONCLUSIONS

Most LTx recipients die or develop BOS within 4 years, and very few remain alive and free from BOS at 10 years post-LTx. Less inclusive Thoracic Transplant Registry analytic methods tend to overestimate BOS-free survival. The Registry would benefit from improved international reporting of BOS and other chronic lung allograft dysfunction (CLAD) events.