Age-dependent Sex Differences in Graft Loss After Kidney Transplantation

Ambulance Service Utilization by Kidney Transplant Recipients

Background

Compared with the general population, kidney transplant recipients (KTRs) frequently visit the emergency department (ED), but much less is known about the characteristics of ED presentations requiring ambulance transport and the impact on subsequent outcomes for KTRs.

Objectives

To identify predictors of ambulance transport to the ED (ambulance-ED) and outcomes (graft failure and mortality) for those who experienced an ambulance-ED event in a cohort of KTRs.

Design

Retrospective cohort study of incident, adult KTRs receiving a transplant from 2008 to 2020.

Setting

Nova Scotia, Canada.

Patients

Adult (≥18 years), Nova Scotian KTRs affiliated with the Atlantic Canada Multi-Organ Transplant Program.

Measurements

Ambulance-ED events were captured for all transplant recipients (following the day of discharge from their initial transplant admission) using electronic records (provided by Emergency Health Services, the sole provider of emergency medical services for Nova Scotia). Ambulance-ED was defined as ambulance transport to the ED following a 911 call; interfacility transfers were excluded. Predictors of ambulance-ED included recipient, donor, immunological, and perioperative characteristics (pertaining to the initial admission for kidney transplantation). Outcomes included graft failure and mortality.

Methods

Predictors of ambulance-ED were analyzed using a multivariable negative binomial regression model and reported using incidence rate ratios (IRRs) and 95% confidence intervals (CIs). The risk of death/graft failure for those with an ambulance-ED within 30 days of hospital discharge following transplantation was analyzed using an adjusted Cox survival analysis and reported using hazard ratios (HRs) and 95% CIs.

Results

A total of 418 patients received a transplant during the study period. A total of 179 (42.8%) experienced one or more ambulance-ED events. Female sex (IRR = 1.60; 95% CI = 1.12-2.29), kidney failure secondary to diabetes (IRR = 2.52; 95% CI = 1.19-5.31), and donor age ≥45 (IRR = 1.50; 95% CI = 1.04-2.15) were all associated with ambulance-ED. There was no significant increase in the risk of death/graft failure for those that experienced ambulance-ED within 30 days of hospital discharge following transplantation (HR = 1.31; 95% CI = 0.44-3.94).

Limitations

A limitation of this study was that ambulance-ED is not a perfect surrogate marker of acute care needs in a population. Important determinants of health such as living situation and socioeconomic status were not available in this data set.

Conclusions

This study highlights the burden of ambulance use for KTRs and provides insight into the need for more optimal follow-up in certain patient subgroups who are at particularly high risk.

Sex and gender as predictors for allograft and patient-relevant outcomes after kidney transplantation

BACKGROUND

Sex, as a biological construct, and gender, defined as the cultural attitudes and behaviours attributed by society, may be associated with allograft loss, death, cancer, and rejection. Other factors, such as recipient age and donor sex, may modify the association between sex/gender and post-transplant outcomes.

OBJECTIVES

We sought to evaluate the prognostic effects of recipient sex and, separately, gender as independent predictors of graft loss, death, cancer, and allograft rejection following kidney or simultaneous pancreas-kidney (SPK) transplantation. We aimed to evaluate this prognostic effect by defining the relationship between recipient sex or gender and post-transplantation outcomes identifying reasons for variations between sexes and genders, and then quantifying the magnitude of this relationship.

SEARCH METHODS

We searched MEDLINE and EMBASE databases from inception up to 12 April 2023, through contact with the Cochrane Kidney and Transplant Information Specialist, using search terms relevant to this review and no language restrictions.

SELECTION CRITERIA

Cohort, case-control, or cross-sectional studies were included if sex or gender were the primary exposure and clearly defined. Studies needed to focus on our defined outcomes post-transplantation. Sex was defined as the chromosomal, gonadal, and anatomical characteristics associated with the biological sex, and we used the terms "males" and "females". Gender was defined as the attitudes and behaviours that a given culture associates with a person's biological sex, and we used the terms "men" and "women".

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the references for eligibility, extracted the data and assessed the risk of bias using the Quality in Prognosis Studies (QUIPS) tool. Whenever appropriate, we performed random-effects meta-analyses to estimate the mean difference in outcomes. The outcomes of interest included the Standardised Outcomes in Nephrology-Kidney Transplant (SONG-Tx) core outcomes, allograft loss, death, cancer (overall incidence and site-specific) and acute or chronic graft rejection.

MAIN RESULTS

Fifty-three studies (2,144,613 patients; range 59 to 407,963) conducted between 1990 and 2023 were included. Sixteen studies were conducted in the Americas, 12 in Europe, 11 in the Western Pacific, four in the Eastern Mediterranean, three in Africa, two in Southeast Asia, and five across multiple regions. All but one study focused on sex rather than gender as the primary exposure of interest. The number identified as male was 54%; 49 studies included kidney transplant recipients, and four studies included SPK transplant recipients. Twenty-four studies included adults and children, 25 studies included only adults, and four studies included only children. Data from 33 studies were included in the meta-analyses. Among these, six studies presented unadjusted hazard ratios (HRs) that assessed the effect of recipient sex on kidney allograft loss. The other studies reported risk ratios (RRs) for the pre-defined outcomes. Notably, the decision to restrict the meta-analyses to unadjusted estimates arose from the variation in covariate adjustment methods across studies, lacking a common set of adjusted variables. Only three studies considered the modifying effect of recipient age on graft loss or death, which is likely crucial to evaluating sex differences in post-transplant outcomes. No studies considered the modifying effect of recipient age on cancer incidence or allograft rejection risk. In low certainty evidence, compared with male recipients, being female may make little or no difference in kidney allograft loss post-transplantation (7 studies, 5843 patients: RR 0.91, 95% CI 0.73 to 1.12; I2 = 73%). This was also observed in studies that included time-to-event analyses (6 studies, 238,937 patients; HR 1.07, 95% CI, 0.95 to 1.20; I2 = 44%). Two recent large registry-based cohort studies that considered the modifying effects of donor sex and recipient age showed that female recipients under 45 years of age had significantly higher graft loss rates than age-matched male recipients in the setting of a male donor. In contrast, female recipients 60 years and older had lower graft loss rates than age-matched male recipients, regardless of donor sex. Compared with male recipients, being female may make little or no difference in death up to 30 years post-transplantation; however, the evidence is very uncertain (13 studies, 60,818 patients: RR 0.94, 95% CI 0.81 to 1.09; I2 = 92%). Studies that considered the modifying effect of recipient age and donor sex showed that female recipients had a higher excess death risk than males under 45 years of age in the setting of a male donor. Compared with male recipients, being female may make little or no difference in cancer incidence up to 20 years post-transplantation; however, the evidence is very uncertain (7 studies, 25,076 patients; RR 0.84, 95% CI 0.70 to 1.01; I2 = 60%). Compared with male recipients, being female may make little or no difference in the incidence of acute and chronic kidney allograft rejection up to 15 years post-transplantation (9 studies, 6158 patients: RR 0.89, 95% CI 0.75 to 1.05; I2 =54%; low certainty evidence). One study assessed gender and reported that when compared with men, women experienced better five-year survival in high (HR 0.71, 95% CI 0.59 to 0.87) and middle-income areas (HR 0.82, 95% CI 0.74 to 0.92), with no difference in low-income areas (HR 0.85, 95% CI 0.72 to 1.01). There was considerable uncertainty regarding any association between sex or gender and post-transplant patient-relevant outcomes. This was primarily due to clinical and methodological heterogeneity. The observed clinical heterogeneity between studies could be attributed to diverse patient characteristics within sample populations. As a result of limited sex-stratified demographic data being provided, further investigation of this heterogeneity was constrained. However, factors contributing to this finding may include recipient age, donor age, types, and sex. Methodological heterogeneity was noted with the interchangeable use of sex and gender, outcome misclassification, the use of different measures of effects, inconsistent covariate profiles, and disregard for important effect modification.

AUTHORS' CONCLUSIONS

There is very low to low certainty evidence to suggest there are no differences in kidney and pancreas allograft survival, patient survival, cancer, and acute and chronic allograft rejection between male and female kidney and SPK transplant recipients.

New Tools for Data Harmonization and Their Potential Applications in Organ Transplantation

In organ transplantation, accurate analysis of clinical outcomes requires large, high-quality data sets. Not only are outcomes influenced by a multitude of factors such as donor, recipient, and transplant characteristics and posttransplant events but they may also change over time. Although large data sets already exist and are continually expanding in transplant registries and health institutions, these data are rarely combined for analysis because of a lack of harmonization. Promoted by the digitalization of the healthcare sector, effective data harmonization tools became available, with potential applications also for organ transplantation. We discuss herein the present problems in the harmonization of organ transplant data and offer solutions to enhance its accuracy through the use of emerging new tools. To overcome the problem of inadequate representation of transplantation-specific terms, ontologies and common data models particular to this field could be created and supported by a consortium of related stakeholders to ensure their broad acceptance. Adopting clear data-sharing policies can diminish administrative barriers that impede collaboration between organizations. Secure multiparty computation frameworks and the artificial intelligence (AI) approach federated learning can facilitate decentralized and harmonized analysis of data sets, without sharing sensitive data and compromising patient privacy. A common image data model built upon a standardized format would be beneficial to AI-based analysis of pathology images. Implementation of these promising new tools and measures, ideally with the involvement and support of transplant societies, is expected to produce improved integration and harmonization of transplant data and greater accuracy in clinical decision-making, enabling improved patient outcomes.

A Multinational Cohort Study Examining Sex Differences in Excess Risk of Death With Graft Function After Kidney Transplant

BACKGROUND

Kidney transplant recipients show sex differences in excess overall mortality risk that vary by donor sex and recipient age. However, whether the excess risk of death with graft function (DWGF) differs by recipient sex is unknown.

METHODS

In this study, we combined data from 3 of the largest transplant registries worldwide (Scientific Registry of Transplant Recipient, Australia and New Zealand Dialysis and Transplant Registry, and Collaborative Transplant Study) using individual patient data meta-analysis to compare the excess risk of DWGF between male and female recipients of a first deceased donor kidney transplant (1988-2019), conditional on donor sex and recipient age.

RESULTS

Among 463 895 individuals examined, when the donor was male, female recipients aged 0 to 12 y experienced a higher excess risk of DWGF than male recipients (relative excess risk 1.68; 95% confidence interval, 1.24-2.29); there were no significant differences in other age intervals or at any age when the donor was female. There was no statistically significant between-cohort heterogeneity.

CONCLUSIONS

Given the lack of sex differences in the excess risk of DWGF (other than in prepubertal recipients of a male donor kidney) and the known greater excess overall mortality risk for female recipients compared with male recipients in the setting of a male donor, future study is required to characterize potential sex-specific causes of death after graft loss.

Gender and kidney transplantation

Kidney transplantation provides the best form of kidney replacement therapy with improvement in quality of life and longevity. However, disparity exists in its availability, utilisation and outcomes, not only due to donor availability or financial constraints but also arising from the influence of biological sex and its sociocultural attribute i.e., Gender. Women make up the majority of kidney donors but are less likely to be counselled regarding transpantation, be waitlisted or receive living/deceased donor kidney. Biological differences also contribute to differences in kidney transplantation among the sexes. Women are more likely to be sensitised owing to pregnancy, especially in multiparous individuals, complicating donor compatibility. A heightened immune system in women, evidenced by more autoimmune illnesses, increases the risk of allograft rejection and loss. Differences in the pharmacokinetics of transplant drugs owing to biological variances could also contribute to variability in outcomes. Transgender medicine is also increasingly becoming a relevant topic of study, providing greater challenges in the form of hormonal manipulations and anatomic changes. It is thus important to determine and study transplantation and its nuances in this backdrop to be able to provide relevant sex and gender-specific interventions and design better practices for optimum kidney transplant utilisation and outcomes.

Influence of donor sex and age on graft outcome in kidney transplantation

BACKGROUND

There is a known recipient sex-dependent association between donor sex and kidney transplant survival. We hypothesized that donor age also modifies the association between donor sex and graft survival.

METHODS

First, deceased donor kidney transplant recipients (1988-2019, n = 461 364) recorded in the Scientific Registry of Transplant Recipients, the Australia and New Zealand Dialysis and Transplant Registry and the Collaborative Transplant Study were analyzed. We used multivariable Cox regression models to estimate the association between donor sex and death censored graft loss, accounting for the modifying effects of recipient sex and donor age; donor age was categorized as 5-19, 20-34, 35-49, 50-59 and ≥60 years. Results from cohort-specific Cox models were combined using individual patient data meta-analysis.

RESULTS

Among female recipients of donors aged <60 years, graft loss hazards did not differ by donor sex; recipients of female donors ≥60 years showed significantly lower graft loss hazards than recipients of male donors of the same age [combined adjusted hazard ratio (aHR) 0.90, 95% CI 0.86-0.94]. Among male recipients, female donors aged <50 years were associated with significantly higher graft loss hazards than same-aged male donors (5-19 years: aHR 1.11, 95% CI 1.02-1.21; 20-34 years: aHR 1.08, 95% CI 1.02-1.15; 35-49 years: aHR 1.07, 95% CI 1.04-1.10). There were no significant differences in graft loss by donor sex among male recipients of donors aged ≥50 years.

CONCLUSION

Donor age modifies the association between donor sex and graft survival. Older female donors were associated with similar or lower hazards of graft failure than older male donors in both male and female recipients, suggesting a better functional reserve of older female donor kidneys.

The combinatorial effect of age and biological sex on alloimmunity and transplantation outcome

Both age and biological sex affect transplantation outcomes. We have recently shown in a large volume clinical analysis utilizing the SRTR data that graft survival is inferior in young female kidney transplant recipients. In this multi-factorial analysis, older female recipients presented with a trend towards improved transplant outcomes compared to both young female recipients and male recipients of any age. Those data supported by reports of those of others suggest that sex and age impact alloimmune responses both, individually and synergistically. Biological sex and hormone levels change throughout a lifetime with recognized effects on longevity in addition to an impact on the development and course of several disease preconditions. Detailed mechanisms of those sex and age-specific aspects have thus far been studied outside of transplantation. Effects on alloimmunity are largely unknown. Moreover, the combinatorial impact that both, biological sex and age have on transplant outcomes is not understood. Here, we summarize available data that analyze how age in combination with biological sex may shape alloimmune responses and affect transplant outcomes.

Mechanisms and consequences of sex differences in immune responses

Biological sex differences refer to differences between males and females caused by the sex chromosome complement (that is, XY or XX), reproductive tissues (that is, the presence of testes or ovaries), and concentrations of sex steroids (that is, testosterone or oestrogens and progesterone). Although these sex differences are binary for most human individuals and mice, transgender individuals receiving hormone therapy, individuals with genetic syndromes (for example, Klinefelter and Turner syndromes) and people with disorders of sexual development reflect the diversity in sex-based biology. The broad distribution of sex steroid hormone receptors across diverse cell types and the differential expression of X-linked and autosomal genes means that sex is a biological variable that can affect the function of all physiological systems, including the immune system. Sex differences in immune cell function and immune responses to foreign and self antigens affect the development and outcome of diverse diseases and immune responses.

Differences in the epidemiology, management and outcomes of kidney disease in men and women

Improved understanding of differences in kidney disease epidemiology, management and outcomes in men and women could help nephrologists to better meet the needs of their patients from a sex- and gender-specific perspective. Evidence of sex differences in the risk and outcomes of acute kidney injury is mixed and dependent on aetiology. Women have a higher prevalence of chronic kidney disease (CKD) stages 3-5 than men, whereas men have a higher prevalence of albuminuria and hence CKD stages 1-2. Men show a faster decline in kidney function, progress more frequently to kidney failure and have higher mortality and risk of cardiovascular disease than women. However, the protective effect of female sex is reduced with CKD progression. Women are less likely than men to be aware of, screened for and diagnosed with CKD, started on antiproteinuric medication and referred to nephrologist care. They also consistently report a poorer health-related quality of life and a higher symptom burden than men. Women experience greater barriers than men to access the waiting list for kidney transplantation, particularly with respect to older age and obesity. However, women also have longer survival than men after transplantation, which may partly explain the comparable prevalence of transplantation between the sexes.

Sex-specific time trends of long-term graft survival after kidney transplantation - a registry-based study

BACKGROUND

Sex-specific trends over time with respect to kidney graft survival have scarcely been described in earlier studies. The present study aimed to examine whether kidney graft survival differs between women and men over time.

METHODS

This study was based on prospectively collected data extracted from a quality registry including all kidney transplant patients between January 1965 and September 2017 at the transplantation center of a university hospital in Sweden. The transplantation center serves a population of approximately 3.5 million inhabitants. Only the first graft for each patient was included in the study resulting in 4698 transplantations from unique patients (37% women, 63% men). Patients were followed-up until graft failure, death, or the end of the study. Death-censored graft survival analysis after kidney transplantation (KT) was performed using Kaplan-Meier analysis with log-rank test, and analysis adjusted for confounders was performed using multivariable Cox regression analysis.

RESULTS

Median age at transplantation was 48 years (quartiles 36-57 years) and was similar for women and men. Graft survival was analyzed separately in four transplantation periods that represented various immunosuppressive regimes (1965-1985, 1986-1995, 1996-2005, and 2006-2017). Sex differences in graft survival varied over time (sex-by-period interaction, p = 0.026). During the three first periods, there were no significant sex differences in graft survival. However, during the last period, women had shorter graft survival (p = 0.022, hazard ratio (HR) 1.71, 95% confidence interval (CI) 1.1-2.7, adjusted for covariates). Biopsy-proven rejections were more common in women.

CONCLUSIONS

In this registry-based study, women had shorter graft survival than men during the last observation period (years 2006-2017).

Prediction models for the recipients' ideal perioperative estimated glomerular filtration rates for predicting graft survival after adult living-donor kidney transplantation

Introduction

The impact of the perioperative estimated glomerular filtration rate (eGFR) on graft survival in kidney transplant recipients is yet to be evaluated. In this study, we developed prediction models for the ideal perioperative eGFRs in recipients.

Methods

We evaluated the impact of perioperative predicted ideal and actual eGFRs on graft survival by including 1,174 consecutive adult patients who underwent living-donor kidney transplantation (LDKT) between January 2008 and December 2020. Prediction models for the ideal perioperative eGFR were developed for 676 recipients who were randomly assigned to the training and validation sets (ratio: 7:3). The prediction models for the ideal best eGFR within 3 weeks and those at 1, 2, and 3 weeks after LDKT in 474 recipients were developed using 10-fold validation and stepwise multiple regression model analyzes. The developed prediction models were validated in 202 recipients. Finally, the impact of perioperative predicted ideal eGFRs/actual eGFRs on graft survival was investigated using Fine-Gray regression analysis.

Results

The correlation coefficients of the predicted ideal best eGFR within 3 weeks and the predicted ideal eGFRs at 1, 2, and 3 weeks after LDKT were 0.651, 0.600, 0.598, and 0.617, respectively. Multivariate analyzes for graft loss demonstrated significant differences in the predicted ideal best eGFR/actual best eGFR within 3 weeks and the predicted ideal eGFRs/actual eGFRs at 1, 2, and 3 weeks after LDKT.

Discussion

The predicted ideal best eGFR/actual best eGFR within 3 weeks and the predicted ideal eGFRs/actual eGFRs at 1, 2, and 3 weeks after LDKT were independent prognostic factors for graft loss. Therefore, the perioperative predicted ideal eGFR/actual eGFR may be useful for predicting graft survival after adult LDKT.

Hormone replacement therapy and COVID-19 outcomes in solid organ transplant recipients compared with the general population

Exogenous estrogen is associated with reduced coronavirus disease (COVID) mortality in nonimmunosuppressed/immunocompromised (non-ISC) postmenopausal females. Here, we examined the association of estrogen or testosterone hormone replacement therapy (HRT) with COVID outcomes in solid organ transplant recipients (SOTRs) compared to non-ISC individuals, given known differences in sex-based risk in these populations. SOTRs ≥45 years old with COVID-19 between April 1, 2020 and July 31, 2022 were identified using the National COVID Cohort Collaborative. The association of HRT use in the last 24 months (exogenous systemic estrogens for females; testosterone for males) with major adverse renal or cardiac events in the 90 days post-COVID diagnosis and other secondary outcomes were examined using multivariable Cox proportional hazards models and logistic regression. We repeated these analyses in a non-ISC control group for comparison. Our study included 1135 SOTRs and 43 383 immunocompetent patients on HRT with COVID-19. In non-ISC, HRT use was associated with lower risk of major adverse renal or cardiac events (adjusted hazard ratio [aHR], 0.61; 95% confidence interval [CI], 0.57-0.65 for females; aHR, 0.70; 95% CI, 0.65-0.77 for males) and all secondary outcomes. In SOTR, HRT reduced the risk of acute kidney injury (aHR, 0.79; 95% CI, 0.63-0.98) and mortality (aHR, 0.49; 95% CI, 0.28-0.85) in males with COVID but not in females. The potentially modifying effects of immunosuppression on the benefits of HRT requires further investigation.

Excess mortality after kidney transplantation: does sex matter?

Understanding sex differences in graft outcomes within the course of kidney transplantation is needed to unravel factors leading to the observed disparities and further improve patient management. In this issue, Vinson et al. presented a relative survival analysis comparing the excess risk of mortality in female and male recipients after kidney transplantation. This commentary discusses the major findings but also the challenges of the use of registry data to conduct large-scale analyses.

A multinational cohort study uncovered sex differences in excess mortality after kidney transplant

Worldwide and at all ages, males have a higher mortality risk than females. This mortality bias should be preserved in kidney transplant recipients unless there are sex differences in the effects of transplantation. Here we compared the excess risk of mortality (risk above the general population) in female versus male recipients of all ages recorded in three large transplant databases. This included first deceased donor kidney transplant recipients and accounted for the modifying effects of donor sex and recipient age. After harmonization of variables across cohorts, relative survival models were fitted in each cohort separately and results were combined using individual patient data meta-analysis among 466,892 individuals (1988-2019). When the donor was male, female recipients 0-12 years (Relative Excess Risk 1.54, 95% Confidence Interval 1.20-1.99), 13-24 years (1.17, 1.01-1.34), 25-44 years (1.11, 1.05-1.18) and 60 years and older (1.05, 1.02-1.08) showed higher excess mortality risks than male recipients of the same age. When the donor was female, the Relative Excess Risk for those over 12 years were similar to those when the donor was male. There is a higher excess mortality risk in female than male recipients with differences larger at younger than older ages and only statistically significant when the donor was male. While these findings may be partly explained by the known sex differences in graft loss risks, sex differences in the risks of death with graft function may also contribute. Thus, higher risks in females than males suggest that management needs to be modified to optimize transplant outcomes among females.

Representation of Women in Contemporary Kidney Transplant Trials

Women are often underrepresented in clinical trials. It is unclear if this applies to trials in kidney transplant (KT) and whether the intervention or trial focus influences this. In this study, the weighted participation-to-prevalence ratio (PPR) for women enrollees in KT trials was determined for leading medical transplant or kidney journals between 2018 and 2023 using meta-regression overall and in three sensitivity analyses by: 1) Whether the intervention involved immunosuppression; 2) Area of trial focus; rejection, cardiometabolic, infection, lifestyle, surgical; 3) Whether the intervention was medical/surgical or social/behavioral. Overall, 33.7% of participants in 24 trials were women. The overall pooled PPR for the included trials was 0.80, 95% CI 0.76-0.85, with significant heterogeneity between trials (I 2 56.6%, p-value < 0.001). Women had a lower PPR when the trial involved immunosuppression (PPR 0.77, 95% CI 0.72-0.82) than when it did not (PPR 0.86, 95% CI 0.80-0.94) and were less likely to participate in trials with a medical/surgical versus behavioral intervention; the lowest PPR for women was in studies examining rejection risk (PPR 0.75, 95% CI 0.70-0.81). There is better representation of women in KT trials compared to other medical disciplines, however women remain underrepresented in transplant trials examining immunosuppression and rejection.

The effect of sex inequality on solid organ transplantation: A systematic review and meta-analysis

BACKGROUND

Sex disparities are related to biological differences, which may have significant impact on patient and allograft outcomes. The aim was to investigate the impact of sex on clinical and safety outcomes after solid organ transplantation (SOT).

METHODS

A systematic review and meta-analysis was performed. Observational studies comparing females vs. males after SOT were considered for inclusion after a systematic search of the Pubmed, Cochrane Library, and Web of Science databases conducted from 2016 to 2021. Primary outcome was mortality. PROSPERO register number: CRD42021282615.

RESULTS

After retrieving 1103 studies, 22 observational studies (1,045,380 subjects) were finally deemed eligible for inclusion. Females accounted 36.3% of SOT recipients, but presented significantly lower mortality (odds ratio (OR): 0.87, 95% confidence interval (CI): 0.83-0.92, I2=78%). In subgroup analyses, mortality was significantly lower in females undergoing liver (OR: 0.89 95%CI: 0.86-0.92, I2=0%) or kidney transplantation (OR: 0.82 95%CI: 0.76-0.89, I2=72%). Male sex was consistently reported as a protective factor against hospital readmission. Among the outcomes, allograft dysfunction was influenced by a combination of donor-recipient sex and age. Data on overall infections were inconclusive. Several reports suggest a higher risk of malignancy among males.

CONCLUSIONS

Females represent one-third of SOT recipients but have higher survival rates than males after liver and kidney transplantation. The impact on graft dysfunction was heterogeneous. While further research is warranted, our findings should encourage clinicians and researchers to consider sex as a factor when taking decisions regarding SOT management.

(Bio)printing in Personalized Medicine—Opportunities and Potential Benefits

The global development of technologies now enters areas related to human health, with a transition from conventional to personalized medicine that is based to a significant extent on (bio)printing. The goal of this article is to review some of the published scientific literature and to highlight the importance and potential benefits of using 3D (bio)printing techniques in contemporary personalized medicine and also to offer future perspectives in this research field. The article is prepared according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Web of Science, PubMed, Scopus, Google Scholar, and ScienceDirect databases were used in the literature search. Six authors independently performed the search, study selection, and data extraction. This review focuses on 3D bio(printing) in personalized medicine and provides a classification of 3D bio(printing) benefits in several categories: overcoming the shortage of organs for transplantation, elimination of problems due to the difference between sexes in organ transplantation, reducing the cases of rejection of transplanted organs, enhancing the survival of patients with transplantation, drug research and development, elimination of genetic/congenital defects in tissues and organs, and surgery planning and medical training for young doctors. In particular, we highlight the benefits of each 3D bio(printing) applications included along with the associated scientific reports from recent literature. In addition, we present an overview of some of the challenges that need to be overcome in the applications of 3D bioprinting in personalized medicine. The reviewed articles lead to the conclusion that bioprinting may be adopted as a revolution in the development of personalized, medicine and it has a huge potential in the near future to become a gold standard in future healthcare in the world.