Sex and Gender-related Disparities in Clinical Characteristics and Outcomes in Heart Transplantation

PURPOSE OF REVIEW

Limited research has been conducted on sex disparities in heart transplant (HT). The aim of this review is to analyse the available evidence on the influence of sex and gender-related determinants in the entire HT process, as well as to identify areas for further investigation.

RECENT FINDINGS

Although women make up half of the population affected by heart failure and related mortality, they account for less than a third of HT recipients. Reasons for this inequality include differences in disease course, psychosocial factors, concerns about allosensitisation, and selection or referral bias in female patients. Women are more often listed for HT due to non-ischaemic cardiomyopathy and have a lower burden of cardiovascular risk factors. Although long-term prognosis appears to be similar for both sexes, there are significant disparities in post-HT morbidity and causes of mortality (noting a higher incidence of rejection in women and of malignancy and cardiac allograft vasculopathy in men). Additional research is required to gain a better understanding of the reasons behind gender disparities in eligibility and outcomes following HT. This would enable the fair allocation of resources and enhance patient care.

Psychosocial Risk and Health Behaviors as Predictors of Clinical Events in Patients Wait-Listed for a New Heart: Results from 7 Years of Follow-Up

We examined the long-term relationship of psychosocial risk and health behaviors on clinical events in patients awaiting heart transplantation (HTx). Psychosocial characteristics (e.g., depression), health behaviors (e.g., dietary habits, smoking), medical factors (e.g., creatinine), and demographics (e.g., age, sex) were collected at the time of listing in 318 patients (82% male, mean age = 53 years) enrolled in the Waiting for a New Heart Study. Clinical events were death/delisting due to deterioration, high-urgency status transplantation (HU-HTx), elective transplantation, and delisting due to clinical improvement. Within 7 years of follow-up, 92 patients died or were delisted due to deterioration, 121 received HU-HTx, 43 received elective transplantation, and 39 were delisted due to improvement. Adjusting for demographic and medical characteristics, the results indicated that frequent consumption of healthy foods (i.e., foods high in unsaturated fats) and being physically active increased the likelihood of delisting due improvement, while smoking and depressive symptoms were related to death/delisting due to clinical deterioration while awaiting HTx. In conclusion, psychosocial and behavioral characteristics are clearly associated with clinical outcomes in this population. Interventions that target psychosocial risk, smoking, dietary habits, and physical activity may be beneficial for patients with advanced heart failure waiting for a cardiac transplant.

Gender differences in psychosocial and clinical characteristics in the European Registry for Patients with Mechanical Circulatory Support

BACKGROUND

Not much is known about psychosocial characteristics of men and women receiving continuous flow left ventricular assist devices (CF LVAD).

OBJECTIVE

To investigate gender differences in clinical and psychosocial (demographic, behavioral, psychological) characteristics in CF LVAD recipients.

METHODS

We analyzed European Registry for Patients with Mechanical Circulatory Support (EUROMACS) data (N=2395, 16.8% women; 2011 to 2017) and compared pre-implant characteristics in men and women intended for bridge-to-transplant (BTT) or destination therapy (DT).

RESULTS

Women were underrepresented [DT (n=61): 13.4%; BTT (n=341): 17.6%]. They were more likely to be divorced/separated, widowed, in unstable clinical condition, and non-working (DT only), but less likely to be smokers, to have ischemic cardiomyopathy or diabetes, and younger (BTT only) than men. Missing data were abundant, especially those that reflect psychological characteristics (>87%).

CONCLUSION

Gender differences were noted, some specific to device strategy. Improved collection of psychosocial characteristics is warranted to elucidate their relationship to future prognosis.

Heart Transplantation: An In-Depth Survival Analysis

OBJECTIVES

This study aims to understand the complex factors affecting heart transplant survival and to determine the importance of possible sex-specific risk factors.

BACKGROUND

Heart transplant allocation is primarily focused on preventing waitlist mortality. To prevent organ wastage, future allocation must balance risk of waitlist mortality with post-transplantation mortality. However, more information regarding risk factors after heart transplantation is needed.

METHODS

We included all adults (30,606) in the Scientific Registry of Transplant Recipients database who underwent isolated heart transplantation from January 1, 2004, to July 1, 2018. Mortality (8,278 deaths) was verified with the complete Social Security Death Index with a median follow-up of 3.9 years. Temporal decomposition was used to identify phases of survival and phase-specific risk factors. The random survival forests method was used to determine importance of mortality risk factors and their interactions.

RESULTS

We identified 3 phases of mortality risk: early post-transplantation, constant, and late. Sex was not a significant risk factor. There were several interactions predicting early mortality such as pretransplantation mechanical ventilation with presence of end-organ function (bilirubin, renal function) and interactions predicting later mortality such as diabetes and older age (donor and recipient). More complex interactions predicting early-, mid-, and late-mortality existed and were identified with machine learning (i.e., elevated bilirubin, mechanical ventilation, and dialysis).

CONCLUSIONS

Post-heart transplant mortality risk is complex and dynamic, changing with time and events. Sex is not an important mortality risk factor. To prevent organ wastage, end-organ dysfunction should be resolved before transplantation as much as possible.

The 2018 ISHLT/APM/AST/ICCAC/STSW recommendations for the psychosocial evaluation of adult cardiothoracic transplant candidates and candidates for long-term mechanical circulatory support

The psychosocial evaluation is well-recognized as an important component of the multifaceted assessment process to determine candidacy for heart transplantation, lung transplantation, and long-term mechanical circulatory support (MCS). However, there is no consensus-based set of recommendations for either the full range of psychosocial domains to be assessed during the evaluation, or the set of processes and procedures to be used to conduct the evaluation, report its findings, and monitor patients' receipt of and response to interventions for any problems identified. This document provides recommendations on both evaluation content and process. It represents a collaborative effort of the International Society for Heart and Lung Transplantation (ISHLT) and the Academy of Psychosomatic Medicine, American Society of Transplantation, International Consortium of Circulatory Assist Clinicians, and Society for Transplant Social Workers. The Nursing, Health Science and Allied Health Council of the ISHLT organized a Writing Committee composed of international experts representing the ISHLT and the collaborating societies. This Committee synthesized expert opinion and conducted a comprehensive literature review to support the psychosocial evaluation content and process recommendations that were developed. The recommendations are intended to dovetail with current ISHLT guidelines and consensus statements for the selection of candidates for cardiothoracic transplantation and MCS implantation. Moreover, the recommendations are designed to promote consistency across programs in the performance of the psychosocial evaluation by proposing a core set of content domains and processes that can be expanded as needed to meet programs' unique needs and goals.

Sex Differences in Mortality Based on United Network for Organ Sharing Status While Awaiting Heart Transplantation

BACKGROUND

There are sex differences in mortality while awaiting heart transplantation, and the reason remains unclear.

METHODS AND RESULTS

We included all adults in the Scientific Registry of Transplant Recipients placed on the heart transplant active waitlist from 2004 to 2015. The primary end point was all-cause mortality. Multivariable Cox proportional hazards models were performed to evaluate survival by United Network for Organ Sharing (UNOS) status at the time of listing. Random survival forest was used to identify sex interactions for the competing risk of death and transplantation. There were 33 069 patients (25% women) awaiting heart transplantation. This cohort included 7681 UNOS status 1A (26% women), 13 027 UNOS status 1B (25% women), and 12 361 UNOS status 2 (26% women). During a median follow-up of 4.3 months, 1351 women and 4052 men died. After adjusting for >20 risk factors, female sex was associated with a significant risk of death among UNOS status 1A (adjusted hazard ratio, 1.14; 95% confidence interval, 1.01-1.29) and UNOS status 1B (adjusted hazard ratio, 1.17; 95% confidence interval, 1.05-1.30). In contrast, female sex was significantly protective for time to death among UNOS status 2 (adjusted hazard ratio, 0.85; 95% confidence interval, 0.76-0.95). Sex differences in probability of transplantation were present for every UNOS status, and >20 sex interactions were identified for mortality and transplantation.

CONCLUSIONS

When stratified by initial UNOS status, women had a higher mortality than men as UNOS status 1 and a lower mortality as UNOS status 2. With >20 sex interactions for mortality and transplantation, further evaluation is warranted to form a more equitable allocation system.

Matching the Market for Heart Transplantation

Heart transplantation is the most effective therapy for patients with Stage D heart failure with a median life expectancy of ≈10 to 15 years. Unfortunately, many patients die on the waiting list hoping for a chance of survival. The life boat cannot rescue everyone. Over a decade, the donor pool has remained relatively stable, whereas the number of heart transplant candidates has risen. Potential recipients often have many comorbidities and are older because the criteria for heart transplantation has few absolute contraindications. Women, Hispanics, and patients with restrictive heart disease and congenital heart disease are more likely to die while awaiting heart transplantation than men, white patients, and those with either ischemic or dilated cardiomyopathy. To better match the market, we need to (1) increase the donor pool, (2) reduce the waitlist, and (3) improve the allocation system. This review article addresses all 3 options and compares strategies in the United States to those in other countries.

Smoking Status at Time of Listing for a Heart Transplant Predicts Mortality on the Waiting List

Objective:

We examined the association of smoking status at time of listing with waitlist mortality among heart transplant (HTx) candidates.

Participants and Design:

Data were analyzed from 316 participants (aged 53 ± 11; 18% female) of the Waiting for a New Heart Study, a prospective observational study of patients newly listed for HTx at 17 hospitals.

Results:

During the study period (April 2005 to March 2010), 14% of those who never smoked died, 18% among former smokers died, and almost half (42%) died among those who reported smoking at time of wait listing. Multivariate Cox regression models controlling for age, sex, and disease severity revealed smoking at time of listing was associated with significantly higher risk of mortality compared to never smoking (hazard ratio [HR] = 3.43; P = .03). The relationship between smoking and mortality risk appeared to follow a dose-dependent pattern: adjusted HRs were 1.80 for those who quit ≤1 year ago, 1.25 for those who quit >1 to 10 years ago, and 0.90 for those quit >10 years ago, compared to never smokers. Smoking at time of listing may increase risk of mortality during the waiting period, indicating the need for improved strategies to achieve smoking cessation as early as possible in the course of HTx.

Does the UNOS heart transplant allocation system favor men over women?

OBJECTIVES

The aim of this paper was to identify sex differences in survival of patients awaiting orthotopic heart transplantation (OHT).

BACKGROUND

Women have a higher mortality rate while awaiting OHT than men, and the reason has not been fully determined.

METHODS

We included all adult patients in the Scientific Registry of Transplant Recipients (SRTR) placed on the OHT waiting list from 2000 to 2010. The primary endpoint was all-cause mortality before receiving OHT, analyzed using time-to-event analysis. Multivariate Cox proportional hazards models were used to evaluate sex differences in survival, with data stratified by United Network for Organ Sharing (UNOS) status at time of listing.

RESULTS

There were 28,852 patients (24% women) awaiting OHT. This cohort included 6,163 UNOS status 1A (25% women), 9,168 UNOS status 1B (25% women), and 13,521 UNOS status 2 (24% women) patients. During a median follow-up of 3.7 years, 1,290 women and 4,286 men died. Female sex was associated with a significant risk of death among UNOS status 1A (adjusted hazard ratio [HR]: 1.20; 95% confidence interval [CI]: 1.05 to 1.37, p = 0.01) after adjusting for more than 30 baseline variables. In contrast, female sex was significantly protective for time to death among UNOS status 2 patients (adjusted HR: 0.75; 95% CI: 0.67 to 0.84, p < 0.001). No sex differences were noted among UNOS status 1B patients.

CONCLUSIONS

There are sex differences in survival between women and men awaiting heart transplantation, and the current UNOS transplant criteria do not account for this disparity.