Donor/recipient sex mismatch and survival after heart transplantation: only an issue in male recipients? An analysis of the Spanish Heart Transplantation Registry

Choosing wisely: incorporating appropriate donor-recipient size matching in heart transplantation

Historically, transplantation of a female donor heart to male recipient has been viewed with caution given evidence of suboptimal outcomes, particularly in special populations such as patients with pulmonary hypertension or those supported by ventricular assist devices. However, the use of predicted heart mass ratio for donor-recipient size matching demonstrated that the size of the organ rather than sex of the donor was most responsible for the outcomes. With the advent of the predicted heart mass ratio, avoiding female donor hearts for male recipients is no longer justified and may result in unnecessary waste of available organs. In this review, we highlight the value of donor-recipient sizing by predicted heart mass ratio and summarize the evidence of different approaches to the donor-to-recipient size and sex matching. We conclude that the utilization of predicted heart mass is currently considered a preferred method of matching heart donors and recipients.

Donor heart selection: Evidence-based guidelines for providers

The proposed donor heart selection guidelines provide evidence-based and expert-consensus recommendations for the selection of donor hearts following brain death. These recommendations were compiled by an international panel of experts based on an extensive literature review.

Sex mismatch following heart transplantation in the United States: Characteristics and impact on outcomes

BACKGROUND

Available literature indicates the possible detrimental effect of sex mismatching on mortality in patients undergoing heart transplantation. Our objective was to examine the role of sex and heart mass (predicted heart mass [PHM]) mismatch on mortality and graft rejection in patients undergoing heart transplantation in the US.

METHODS

Data on adult patients who underwent heart transplantation between January 2015 and October 2021 were queried from the United Network of Organ Sharing (UNOS) registry. The main outcomes were all-cause mortality, 1-year all-cause mortality and treated acute rejection.

RESULTS

A total of 19 805 adult patients underwent heart transplant during the study period. 92.2% of the patients in the female graft to male group had a PHM mismatch <25%, while only 38.5% had such a mismatch in the male graft to female group. In male to male and female to female groups, 79% and 76% of the patients had a PHM mismatch <25% (p = .122). Proportion of PHM mismatch was similar throughout the study period. Unadjusted analysis showed that male recipients of female grafts had increased risk for all-cause mortality (hazard ratio [HR]: 1.13; 95% confidence intervals [CI]: 1.02, 1.27; p = .026) and 1-year mortality (HR: 1.26; 95% CI: 1.09, 1.45; p = .002) compared to male recipients of male grafts. Graft failure incidence was also higher (HR: 1.12; 95% CI: 1.01, 1.25; p = .041). However, all these associations were non- significant after risk factor adjustment.

CONCLUSIONS

Sex mismatching is associated with post-transplant mortality with transplantation of female donor grafts to male recipients demonstrating worse outcomes, although this association disappears after risk factor adjustment. Further research is required to elucidate the need for potential changes in clinical practice.

Validation of days alive and out of hospital as a new patient-centered outcome to quantify life impact after heart transplantation

The number of patients waiting for heart transplantation (HTX) is increasing. Thus, identification of outcome-relevant factors is crucial. This study aimed to identify perioperative factors associated with days alive and out of hospital (DAOH)-a patient-centered outcome to quantify life impact-after HTX. This retrospective cohort study screened 187 patients who underwent HTX at university hospital Duesseldorf, Germany from September 2010 to December 2020. The primary endpoint was DAOH at 1 year. Risk factors for mortality after HTX were assessed in univariate analysis. Variables with significant association were entered into multivariable quantile regression. In total, 175 patients were included into analysis. Median DAOH at 1 year was 295 (223-322) days. In univariate analysis the following variables were associated with reduced DAOH: recipient or donor diabetes pre-HTX, renal replacement therapy (RRT), VA-ECMO therapy, recipient body mass index, recipient estimated glomerular filtration rate (eGFR) and postoperative duration of mechanical ventilation. After adjustment, mechanical ventilation, RRT, eGFR and recipient diabetes showed significant independent association with DAOH. This study identified risk factors associated with reduced DAOH at 1-year after HTX. These findings might complement existing data for outcome of patients undergoing HTX.

A framework for developing sex-specific engineered heart models

The convergence of tissue engineering and patient-specific stem cell biology has enabled the engineering of in vitro tissue models that allow the study of patient-tailored treatment modalities. However, sex-related disparities in health and disease, from systemic hormonal influences to cellular-level differences, are often overlooked in stem cell biology, tissue engineering and preclinical screening. The cardiovascular system, in particular, shows considerable sex-related differences, which need to be considered in cardiac tissue engineering. In this Review, we analyse sex-related properties of the heart muscle in the context of health and disease, and discuss a framework for including sex-based differences in human cardiac tissue engineering. We highlight how sex-based features can be implemented at the cellular and tissue levels, and how sex-specific cardiac models could advance the study of cardiovascular diseases. Finally, we define design criteria for sex-specific cardiac tissue engineering and provide an outlook to future research possibilities beyond the cardiovascular system.

Impact of various sizing metrics on female donor to male recipient heart transplant outcomes

BACKGROUND

This study evaluated the impact of various sizing metrics on outcomes of female donor to male recipient orthotopic heart transplantation (OHT).

METHODS

We queried the United Network of Organ Sharing database to analyze all isolated, primary adult OHTs from January 1, 2010 to January 20, 020. Patients were stratified by donor-recipient sex pairing. Logistic regression was used to investigate risk-adjusted effects of current size matching criteria (weight ratio, body mass index [BMI] ratio, predicted heart mass [pHM] ratio) on 1-year posttransplant mortality. Kaplan-Meier analysis was used to compare posttransplant survival among cohorts.

RESULTS

A total of 22,450 patients were analyzed, of which 3019 (13.4%) underwent female-to-male transplantation. Of sex-matched pairs, female-to-male donation had the lowest proportion of undersized hearts using weight and BMI ratio metrics (10.5% and 5.2%) but had the highest proportion of undersizing using pHM metrics (48.1%) (all p < 0.001). Female-to-male recipients had the lowest rate of unadjusted 1-year survival (90.0%, p = 0.0169), and increased hazards of mortality after risk adjustment (odds ratio [OR]: 1.17, 95% confidence interval [CI]: 1.01-1.36, p = 0.034). Undersizing using pHM (donor-recipient ratio <0.85) was the only metric found to be associated in increased mortality after risk adjustment (OR: 1.32, 95% CI: 1.02-1.71, p = 0.035).

CONCLUSION

Female-to-male heart transplantation has the worst survival of all sex-matching combinations. Although female donors in this cohort are appropriately sized using traditional metrics, half are under-sized using pHM. This, combined with its strong association with mortality, underscores the importance of routine pHM assessment when evaluating female donors for male recipients.

Influence of Sex-Mismatch on Prognosis After Heart Transplantation

The influence of donor and recipient sex on prognosis after heart transplantation has been analyzed in single, multi-center studies, and international registries. In most of them, sex-mismatch was identified as a risk factor for the worst prognosis, especially in men recipients of female heart. This could be attributed to physiological differences between women and men, differences in complications rates after heart transplantation (rejection, cardiovascular allograft vasculopathy, and primary graft failure), and pulmonary hypertension of the recipient. Confounding variables as age, urgent transplantation, and size-mismatch should also be considered. When allocating a graft, sex-mismatch should be considered but its influence in long-term survival should be further explored.

Influence of Gender in Advanced Heart Failure Therapies and Outcome Following Transplantation

Biological differences between males and females change the course of different diseases and affect therapeutic measures' responses. Heart failure is not an exception to these differences. Women account for a minority of patients on the waiting list for heart transplantation or other advanced heart failure therapies. The reason for this under-representation is unknown. Men have a worse cardiovascular risk profile and suffer more often from ischemic heart disease. Conversely, transplanted women are younger and more frequently have non-ischemic cardiac disorders. Women's poorer survival on the waiting list for heart transplantation has been previously described, but this trend has been corrected in recent years. The use of ventricular assist devices in women is progressively increasing, with comparable results than in men. The indication rate for a heart transplant in women (number of women on the waiting list for millions of habitants) has remained unchanged over the past 25 years. Long-term results of heart transplants are equal for both men and women. We have analyzed the data of a national registry of heart transplant patients to look for possible future directions for a more in-depth study of sex differences in this area. We have analyzed 1-year outcomes of heart transplant recipients. We found similar results in men and women and no sex-related interactions with any of the factors related to survival or differences in death causes between men and women. We should keep trying to approach sex differences in prospective studies to confirm if they deserve a different approach, which is not supported by current evidence.

Size matching in heart transplantation: Is predicted heart mass the optimal method in a United Kingdom cohort?

Predicted heart mass (PHM) equations have been proposed as an alternative method for size matching in heart transplantation. We assessed association between donor-recipient size mismatch, defined using PHM equations, and survival post-heart transplant in the United Kingdom. Data from all adult patients who received a heart transplant between 1995 and 2017 were obtained from the United Kingdom Transplant Registry. PHM was calculated using published equations. Primary outcome was 1-year survival post-heart transplantation. Recipients of undersized organs had reduced 1-year survival (HR 1.31, 95% CI 1.03-1.67, p = .03). Oversizing had no impact on survival (HR 0.99, 95% CI 0.78-1.26, p = .96). Gender mismatching had no impact on survival in the cohort matched by PHM (HR 1.12, 95% CI 0.86-1.47, p = .4). In recipients without pulmonary hypertension, undersizing by PHM had no impact on 1-year survival (HR 0.95, 95% CI 0.61-1.49, p = .83). In recipients with pulmonary hypertension, oversizing donor RV by using PHM RV equation (PHM_RV ) results in improved survival at 1 year (HR 0.65, 95% CI 0.5-0.83, p = .001). In conclusion, receiving an organ undersized by PHM was associated with decreased 1-year survival. Subgroup analyses demonstrated that undersizing only impacted survival in recipients with pulmonary hypertension and that these recipients had improved outcomes if they received an organ with an RV oversized by >10% by PHM_RV .

Sex Influence on Heart Failure Prognosis

Heart failure (HF) affects 1-2% of the population in developed countries and ~50% of patients living with it are women. Compared to men, women are more likely to be older and suffer hypertension, valvular heart disease, and non-ischemic cardiomyopathy. Since the number of women included in prospective HF studies has been low, much information regarding HF in women has been inferred from clinical trials observations in men and data obtained from registries. Several relevant sex-related differences in HF patients have been described, including biological mechanisms, age, etiology, precipitating factors, comorbidities, left ventricular ejection fraction, treatment effects, and prognosis. Women have greater clinical severity of HF, with more symptoms and worse functional class. However, females with HF have better prognosis compared to males. This survival advantage is particularly impressive given that women are less likely to receive guideline-proven therapies for HF than men. The reasons for this better prognosis are unknown but prior pregnancies may play a role. In this review article we aim to describe sex-related differences in HF and how these differences might explain why women with HF can expect to survive longer than men.

Gender differences in heart transplantation: Twenty-five year trends in the nationwide Spanish heart transplant registry

The study of gender differences may lead into improvement in patient care. We have aimed to identify the gender differences in heart transplantation (HT) of adult HT recipients in Spain and their evolution in a study covering the years 1993-2017 in which 6740 HT (20.6% in women) were performed. HT indication rate per million inhabitants was lower in women, remaining basically unchanged during the 25-year study period. HT rate was higher in men, although this decreased over the 25-year study period. Type of heart disease differed in men versus women (p < .001): ischemic heart disease 47.6% versus 22.5%, dilated cardiomyopathy 41.3% versus 34.6%, or other 36% versus 17.8%, respectively. Men were more frequently diabetics (18% vs. 13.1% p < .001), hypertensives (33.1% vs. 24% p < .001), and smokers (21.7% vs. 12.9% p < .001), respectively. Women had more pre-HT malignancies (7.1% vs. 2.8% p < .001), and their clinical status was worse at HT due to renal function and mechanical ventilation. Adjusted survival (p = .198) and most of the mortality-related variables were similar in men and women. Death occurred more frequently in women due to rejection (7.9% vs. 5.1% p < .001) and primary failure (18.2% vs. 12.5% p < .001) and in men due to malignancies (15.1% vs. 6.6% p < .001).

Ethical Issues in Decision-making Regarding the Elderly Affected by Coronavirus Disease 2019: An Expert Opinion

The coronavirus disease 2019 (COVID-19) pandemic is resulting in ethical decisions regarding resource allocation. Prioritisation reflects established practices that regulate the distribution of finite resources when demand exceeds supply. However, discrimination based on sex, race or age has no role in prioritisation unless clearly justified. The risk posed by COVID-19 is higher for elderly people than for younger people, so older adults should be prioritised in preventive measures. In the case of people who already have COVID-19, healthcare professionals might prioritise those most likely to survive. Making decisions based on chronological age alone is not justified; in addition to age, other aspects that determine theoretical life expectancy must be taken into account. Individualised correct prioritisation in the allocation of scarce resources is essential to good clinical practice.

Sex-mismatch influence on survival after heart transplantation: A systematic review and meta-analysis of observational studies

INTRODUCTION AND OBJECTIVES

Heart transplantation (HT) is the treatment for patients with end-stage heart disease. Despite contradictory reports, survival seems to be worse when donor/recipient sex is mismatched. This systematic review and meta-analysis aims to synthesize the evidence on the effect of donor/recipient sex mismatch after HT.

METHODS

We searched PubMed and EMBASE until November 2017. Comparative cohort and registry studies were included. Published articles were systematically selected and, when possible, pooled in a meta-analysis. The primary endpoint was one-year mortality.

RESULTS

After retrieving 556 articles, ten studies (76 175 patients) were included in the quantitative meta-analysis. Significant differences were found in one-year survival between sex-matched and mismatched recipients (odds ratio (OR) 1.30, 95% confidence interval (CI) 1.25-1.35, P < .001). In female recipients, we found that sex mismatch was not a risk factor for one-year mortality (OR = 0.93, 95% CI = 0.85-1.00, P = .06). However, in male recipients, we found that it was a risk factor for one-year mortality (OR = 1.38, 95% CI = 1.31-1.44, P < .001).

CONCLUSIONS

Sex mismatch increases one-year mortality after HT in male recipients. Its influence in long-term survival should be further explored with high-quality studies.

Sex matching does not impact the outcome after simultaneous pancreas-kidney transplantation

Background

Several studies in solid organ transplantation have shown a correlation between donor and recipient sex mismatch and risk of graft loss. In this study, we aimed to analyze the impact of donor and recipient sex matching on patient and pancreas graft survival in a large single‐center cohort.

Methods

We retrospectively analyzed all first simultaneous pancreas‐kidney transplants performed between 1979 and 2017 at the Medical University of Innsbruck.

Results

Of 452 patients, 54.6% (247) received a sex‐matched transplant. Patient survival (P = .86), death‐censored pancreas graft survival (dcPGS, P = .26), and death‐censored kidney graft survival (dcKGS, P = .24) were similar between the sex‐matched and sex‐mismatched groups. Patient survival and dcPGS at 1, 5, and 15 years were 95.9%, 90.0%, and 62.1% and 86.1%, 77.1%, and 56.7% in the sex‐matched group and 93.6%, 86.2%, and 62.4% and 83.1%, 73.3%, and 54.3% in the sex‐mismatched group. Sex matching led to a lower odds of severe postoperative complications (41.2% vs 49.0%; OR 0.57, 95%CI 0.33‐0.97; P = .038); however, no increased odds of other adverse postoperative outcomes was detected.

Conclusion

Our study demonstrates that sex matching reduced the odds of postoperative complications but did not impact other early and late outcome parameters in our cohort.

[Left ventricle myocardium hypertrophy of donor heart: the results and outlook]

Left ventricular hypertrophy - is one of the most frequent structural changes in the heart. This article is devoted to the assessment of modern views on the causes of myocardial hypertrophy of the donor heart, indications and contraindications for the heart trans‑ plantation, the outlook of expanding the pool of effective donors through the use of these hearts. Here are considered the issues of post-transplantation remodeling of the donor heart myocardium, The pathogenesis features, the nascence risk and possibilities of drug regulation of the transplanted heart's myocardial hypertrophy of the left ventricle.

Increasing heart transplant donor pool by liberalization of size matching

BACKGROUND

The heart transplant (HT) guidelines recommendation to match recipient and donors within 30% of body weight lacks a strong evidence base and is not well established in patients bridged to transplant with left ventricular assist devices (LVAD). In light of the scarcity of donor hearts, we investigated the effect of size mismatch on hemodynamics, one-year survival and length of stay (LOS) following HT.

METHODS

Single-center retrospective analysis of consecutive HT patients from April 2007 to September 2017. Recipients were divided into 3 cohorts based on donor-to-recipient weight ratio (DRWR): (1) undersized (<0.7), (2) size-matched, (0.7-1.3); (3) oversized (>1.3).

RESULTS

288 consecutive patients were identified (mean age 53 ± 11 years; 76% male), 46 were undersized (0.61 ± 0.05), 210 size-matched (0.94 ± 0.16), and 32 oversized (1.65 ± 0.38). There was no significant difference in donor left ventricular end diastolic diameter (LVEDD) between the 3 groups (p = 0.11). The donor/recipient (D/R) predicted heart mass (PHM) was lowest in the undersized group (0.92 ± 0.13). There were no significant differences in 1-year survival in the overall and LVAD cohort (p = 0.65 and 0.59, respectively). Neither donor LVEDD nor D/R PHM differed among survivors or non-survivors. LOS was longer in the undersized group than the size-matched cohort (p = 0.004). The undersized group had hearts with the highest filling pressures and lowest cardiac index at 1 week among the remaining groups (p = 0.009, 0.017, and p = 0.05, respectively). There were no clinically significant differences in hemodynamics at 1 or 6 months.

CONCLUSIONS

HT undersizing affects hemodynamics early but not later in the course and does not impact 1-year survival. The liberalization of size matching may increase the HT donor pool significantly.

Consequences of donor-derived passengers (pathogens, cells, biological molecules and proteins) on clinical outcomes

It is recognized that donor factors contribute to lung transplant outcomes. Recent observations and studies have started to elucidate potential mechanisms behind explaining these observations. This perspective piece summarizes evolving lung transplant literature on the subject, focusing on donor "passenger" organisms, cells, hormones, and proteins transferred to the recipient. Many extrinsic and intrinsic donor features or properties have important consequences for subsequent allograft function in the recipient. Potentially, a better understanding of these features may provide useful novel therapeutic targets to enhance allograft outcomes.

Impact of gender on echocardiographic characteristics in heart transplant recipients

AIMS

Assessment following heart transplantation (HTx) is routinely performed using transthoracic echocardiography. Differences in long-term mortality following HTx related to donor-recipient matching have been reported, but effects of gender on cardiac size and function are not well studied. The aims of this study were to evaluate differences in echocardiographic characteristics of HTx recipients defined by gender.

METHODS AND RESULTS

The study prospectively enrolled 123 (n = 34 female) HTx recipients of which 23 recipients was donor-recipient gender mismatched. Patients were examined with 2-dimensional echocardiography using Philips iE33 ultrasound system. Data were analysed across strata based on recipient gender and gender mismatch. Male recipients had larger left ventricular (LV) mass, thicker septal wall (P<0·001) and larger absolute LV volumes (P<0·001). Mean LV ejection fraction (EF) was higher in females (P<0·05), but no differences in conventional parameters of right ventricular (RV) function were found. Ventricular strain was higher in females than in males: LV global longitudinal strain (P<0·01), RV global longitudinal strain (P<0·05) and RV lateral free wall (P<0·05). The male group receiving a female donor heart had comparable EF and strain parameters to the female group receiving a gender-matched heart.

CONCLUSION

We found that female recipient gender was associated with smaller chamber size, higher LV EF and better LV and RV longitudinal strain. Gender-mismatched male recipients appeared to exhibit function parameters similar to gender-matched female recipients. Our results indicate that the gender aspect, analogous to current reference guidelines in general population, should be taken into consideration when examining patients post-HTx.

Primary graft dysfunction after heart transplantation: Incidence, trends, and associated risk factors

Changes in heart transplantation (HT) donor and recipient demographics may influence the incidence of primary graft dysfunction (PGD). We conducted a retrospective study to evaluate PGD incidence, trends, and associated risk factors by analyzing consecutive adult patients who underwent HT between January 2009 and December 2014 at our institution. Patients were categorized as having PGD using the International Society for Heart & Lung Transplantation (ISHLT)-defined criteria. Variables, including clinical and demographic characteristics of donors and recipients, were selected to assess their independent association with PGD. A time-trend analysis was performed over the study period. Three-hundred seventeen patients met inclusion criteria. Left ventricular PGD, right ventricular PGD, or both, were observed in 99 patients (31%). Risk factors independently associated with PGD included ischemic time, recipient African American race, and recipient amiodarone treatment. Over the study period, there was no change in the PGD incidence; however, there was an increase in the recipient pretransplantation use of amiodarone. The rate of 30-day mortality was significantly elevated in those with PGD versus those without PGD (6.06% vs 0.92%, P = .01). Despite recent advancements, incidence of PGD remains high. Understanding associated risk factors may allow for implementation of targeted therapeutic interventions.

Recovery of renal function in a heart transplantation recipient with over 300 days of iatrogenic anuria: A case report

RATIONALE

Anuria is a severe symptom indicating severe kidney damage. Patient recovery from prolonged anuria is rarely reported.

PATIENT CONCERNS

A 15-year-old boy received gender- and weight-mismatch heart transplantation (HT) due to dilated cardiomyopathy. He developed severe hypotension, and heart failure 24 hours after surgery, which were relieved by preload reduction treatments. Although, routine examinations did not show any abnormalities in renal function before surgery, anuria occurred 4 days after preload reduction treatments (24-hour urine volume was 23 mL).

DIAGNOSIS

The patient was diagnosed with acute kidney injury (AKI).

INTERVENTIONS

He was admitted to continuous renal replacement therapy (CRRT) or hemodialysis.

OUTCOMES

Surprisingly, his urine volume was gradually, and miraculously, restored to more than 1000 mL/24 hours after over 300 days of anuria. Hemodialysis was not needed in the twentieth month after surgery. Moreover, he partially, recovered renal function.

LESSONS

This case indicates the likelihood of recovery from long-term anuria.

The Impact of Sex on Alloimmunity

Transplantation outcomes are known to be affected by multiple factors, including donor and recipient sex. Aside from the physiological characteristics of male and female donor allografts, accumulating evidence suggests that additional features underlie sex-specific immune responses that affect graft survival. We discuss here aspects of innate and adaptive alloimmunity that are specific to males and females in the context of underlying genetic and hormonal factors. These differences likely contribute to the observed disparities in graft survival. Understanding these features in more detail may lead to improved strategies for optimizing the results of organ transplantation.

Predictors of 1-year mortality in heart transplant recipients: a systematic review and meta-analysis

Objective

A systematic summary of the observational studies informing heart transplant guideline recommendations for selection of candidates and donors has thus far been unavailable. We performed a meta-analysis to better understand the impact of such known risk factors.

Methods

We systematically searched and meta-analysed the association between known pretransplant factor and 1-year mortality identified by multivariable regression models. Our review used the Grading of Recommendations, Assessment, Development and Evaluation for assessing the quality of assessment. We pooled risk estimates by using random effects models.

Results

Recipient variables including age (HR 1.16 per 10-year increase, 95% CI 1.10–1.22, high quality), congenital aetiology (HR 2.35, 95% CI 1.62 to 3.41, moderate quality), diabetes (HR 1.37, 95% CI 1.15 to 1.62, high quality), creatinine (HR 1.11 per 1 mg/dL increase, 95% CI 1.06 to 1.16, high quality), mechanical ventilation (HR 2.46, 95% CI 1.48 to 4.09, low quality) and short-term mechanical circulatory support (MCS) (HR 2.47, 95% CI 1.04 to 5.87, low quality) were significantly associated with 1-year mortality. Donor age (HR 1.20 per 10-year increase, 95% CI 1.14 to 1.26, high quality) and female donor to male recipient sex mismatch (HR 1.38, 95% CI 1.06 to 1.80, high quality) were significantly associated with 1-year mortality. None of the operative factors proved significant predictors.

Conclusion

High-quality and moderate-quality evidence demonstrates that recipient age, congenital aetiology, creatinine, pulsatile MCS, donor age and female donor to male recipient sex mismatch are associated with 1-year mortality post heart transplant. The results of this study should inform future guideline and predictive model development.

Five myths about variable selection

Multivariable regression models are often used in transplantation research to identify or to confirm baseline variables which have an independent association, causally or only evidenced by statistical correlation, with transplantation outcome. Although sound theory is lacking, variable selection is a popular statistical method which seemingly reduces the complexity of such models. However, in fact, variable selection often complicates analysis as it invalidates common tools of statistical inference such as P-values and confidence intervals. This is a particular problem in transplantation research where sample sizes are often only small to moderate. Furthermore, variable selection requires computer-intensive stability investigations and a particularly cautious interpretation of results. We discuss how five common misconceptions often lead to inappropriate application of variable selection. We emphasize that variable selection and all problems related with it can often be avoided by the use of expert knowledge.

Mortality, rehospitalization, and post-transplant complications in gender-mismatched heart transplant recipients

BACKGROUND

Limited research has been published on outcomes in heart transplant (HT) recipients with gender-mismatched donors.

OBJECTIVE

Compare 3-year post-transplant outcomes in 2 groups of gender-mismatched HT recipients and a no-mismatch group.

METHODS

Sample: 347 HT recipients: 21.3% (74) received a heart from the opposite gender: Group 1: same gender donor/recipient (273, 78.7%); Group 2: female donor/male recipient (40, 11.5%); Group 3: male donor/female recipient (34, 9.8%).

OUTCOMES

mortality, hospitalization, and complications.

RESULTS

Female patients with male heart donors had shorter 3-year survival, were rehospitalized more days after HT discharge, and had more treated acute rejection episodes and cardiac allograft vasculopathy. No differences were found in: HT length of stay, respiratory failure, stroke, cancer, renal dysfunction, steroid-induced diabetes, number of IV-treated infections, or the timing of infection and rejection.

CONCLUSION

Female HT recipients with male donors had worse 3-year outcomes as compared to male-mismatch and no-mismatch groups.

Influence of donor-recipient sex mismatch on long-term survival of pancreatic grafts

To assess the role of sex mismatch on graft survival after pancreas transplantation. We evaluated 24,195 pancreas-transplant recipients reported in the Scientific Registry of Transplant Recipients over a 25-year period. Pancreatic graft survival (PGS) was analyzed according to donor–recipient sex pairing using Kaplan–Meier estimations. Hazard ratios were estimated using Cox proportional hazard models. A total of 14,187 male and 10,008 female recipients were included in final analyses. Mean follow-up was 8.3 ± 5.7 years. In multivariate analyses, neither recipient sex nor donor sex was associated with pancreatic graft failure (PGF), but donor–recipient sex mismatch (regardless of recipient sex) was an independent predictor of PGS (HR, 1.09; 95% CI, 1.04–1.14; p < 0.001). Compared with M → M sex-matched recipients in univariate analyses, M → F and F → M sex mismatches were associated with an increased risk of PGF. Adjustment for significant recipient and donor factors eliminated the association between F → M sex mismatch and PGF (HR, 1.02; 95% CI, 0.93–1.10; p = 0.752), but not M → F (1.09; 1.02–1.17; 0.020). Stratified analyses suggested that the negative effect of donor–recipient sex mismatch could be neutralized in older patients. These findings suggest that donor–recipient sex pairing should be taken into consideration in organ-allocation strategies.

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

BACKGROUND

The overall life expectancy of women with cystic fibrosis (CF) is shorter compared with men with CF without accounting for lung transplant recipients. However, it is unclear how donor and recipient gender impact long-term outcomes in patients with CF who undergo lung transplantation. The purpose of this study was to determine if the gender disadvantage seen in women with CF before transplant continues to exist after lung transplant and if this is impacted by donor gender.

METHODS

Patients with CF entered in the International Society for Heart and Lung Transplantation registry who were at least 18 years old and received a lung transplant between January 2000 and December 2012 were included and divided into groups based on donor-recipient gender combinations. Kaplan-Meier curves were used to determine post-transplant rates of overall survival and bronchiolitis obliterans syndrome (BOS)-free survival.

RESULTS

The analysis included 4,971 patients undergoing lung transplantation for CF. There was no significant difference in BOS-free survival or overall survival rates between genders or between gender-matched vs gender-mismatched recipients after lung transplantation. However, women with CF underwent transplantation at a younger age and died at an earlier overall age than men with CF.

CONCLUSIONS

Survival after lung transplantation and time to the development of BOS did not differ based on gender or donor-recipient gender combination. However, women with CF continue to demonstrate a poorer overall life expectancy, as their pre-transplant disadvantage could not be overcome after lung transplantation.