Comparison of cause of death between Australian and New Zealand Dialysis and Transplant Registry and the Australian National Death Index

Comparison of Vital Status, Cause of Death, and Follow-Up after Hematopoietic Cell Transplantation in Linked Center for International Blood and Marrow Transplant Research and California Cancer Registry Data, 1991 to 2018

Assessing outcomes following hematopoietic cell transplantation (HCT) poses challenges due to the necessity for systematic and often prolonged patient follow-up. Linking the HCT database of the Center for International Blood and Marrow Transplant Research (CIBMTR) with cancer registry data may improve long-term outcome ascertainment, but the reliability of mortality data in death certificates from cancer registries among HCT recipients remains unknown. We compared the classification of vital status and primary cause of death (COD), as well as the length of follow-up between the CIBMTR and California Cancer Registry (CCR) to assess the possibility of supplementing the CIBMTR with cancer registry data. This retrospective study leveraged a linked CIBMTR-CCR dataset. We included patients who were California residents at the time of HCT and received a first allogeneic (allo) or autologous (auto) HCT for a hematologic malignancy diagnosed during 1991-2016. Follow-up was through 2018. We analyzed 18,450 patients (alloHCT, n = 8232; autoHCT, n = 10,218). The Vital status agreement was 97.7% for alloHCT and 97.2% for autoHCT. Unknown COD was higher in CIBMTR (12.9%) than in CCR (1.6%). After excluding patients with unknown COD information, the overall agreement of primary COD (cancer versus noncancer) was 53.7% for alloHCT and 83.2% for autoHCT. This agreement was lower within the first 100 days post-HCT (alloHCT, 31.0%; autoHCT, 54.6%). Compared with CIBMTR, deaths due to cancer were higher in CCR (alloHCT, 90.0%; autoHCT, 90.1% versus alloHCT, 47.3%; autoHCT, 82.5% in CIBMTR). CIBMTR reports more frequently noncancer-related deaths, including graft-versus-host disease and infections. The cumulative incidence of cancer-specific mortality at 20 years differed, particularly for alloHCT (CCR, 53.7%; CIBMTR, 27.6%). The median follow-up among alive patients was longer in CCR (alloHCT, 6.0 years; autoHCT, 4.7 years) than in CIBMTR (alloHCT, 5.0 years; autoHCT, 3.8 years). Our findings highlight the completeness of vital status data in CIBMTR but reveal substantial disagreement in primary COD. Consequently, caution is required when interpreting HCT studies that use only death certificates to estimate cause-specific mortality outcomes. Improving the accuracy of COD registration and follow-up completeness by developing communication pathways between cancer registries and hospital-based cohorts may enhance our understanding of late effects and long-term outcomes among HCT survivors.

Epidemiology of Cancer in Kidney Transplant Recipients

Kidney transplantation is the ideal treatment modality for patients with end-stage kidney disease, with excellent outcomes post-transplant compared with dialysis. However, kidney transplant recipients are at increased risk of infections and cancer because of the need for immunosuppression. Kidney transplant recipients have approximately two to three times greater risk of developing cancer than the general population, and cancer is a major contributor to morbidity and mortality. Most of the increased risk is driven by viral-mediated cancers such as post-transplant lymphoproliferative disorder, anogenital cancers, and Kaposi sarcoma. Nonmelanoma skin cancer is the most frequent type of cancer in kidney transplant recipients, likely due to an interaction between ultraviolet radiation exposure and decreased immune surveillance. Occurrence of the more common types of solid organ cancers seen in the general population, such as breast, prostate, lung, and colorectal cancers, is not, or is only mildly, increased post-transplant. Clinical care and future research should focus on prevention and on improving outcomes for important immunosuppression-related malignancies, and treatment options for other cancers occurring in the transplant setting.

Life Years Lost in Children with Kidney Failure: A Binational Cohort Study with Multistate Probabilities of Death and Life Expectancy

SIGNIFICANCE STATEMENT

In children with kidney failure, little is known about their treatment trajectories or the effects of kidney failure on lifetime survival and years of life lost, which are arguably more relevant measures for children. In this population-based cohort study of 2013 children who developed kidney failure in Australia and New Zealand, most children were either transplanted after initiating dialysis (74%) or had a preemptive kidney transplant (14%). Life expectancy increased with older age at kidney failure, but more life years were spent on dialysis than with a functioning transplant. The expected (compared with the general population) number of life years lost ranged from 16 to 32 years, with female patients and those who developed kidney failure at a younger age experiencing the greatest loss of life years.

BACKGROUND

Of the consequences of kidney failure in childhood, those rated as most important by children and their caregivers are its effects on long-term survival. From a life course perspective, little is known about the experience of kidney failure treatment or long-term survival.

METHODS

To determine expected years of life lost (YLL) and treatment trajectory for kidney failure in childhood, we conducted a population-based cohort study of all children aged 18 years or younger with treated kidney failure in Australia (1980-2019) and New Zealand (1988-2019).We used patient data from the CELESTIAL study, which linked the Australian and New Zealand Dialysis and Transplant registry with national death registers. We estimated standardized mortality ratios and used multistate modeling to understand treatment transitions and life expectancy.

RESULTS

A total of 394 (20%) of 2013 individuals died over 30,082 person-years of follow-up (median follow-up, 13.1 years). Most children (74%) were transplanted after initiating dialysis; 14% (18% of male patients and 10% of female patients) underwent preemptive kidney transplantation. Excess deaths (compared with the general population) decreased dramatically from 1980 to 1999 (from 41 to 22 times expected) and declined more modestly (to 17 times expected) by 2019. Life expectancy increased with older age at kidney failure, but more life years were spent on dialysis than with a functioning transplant. The number of YLL ranged from 16 to 32 years, with the greatest loss among female patients and those who developed kidney failure at a younger age.

CONCLUSIONS

Children with kidney failure lose a substantial number of their potential life years. Female patients and those who develop kidney failure at younger ages experience the greatest burden.

Variations in Risk of Cancer and Death From Cancer According to Kidney Allograft Function, Graft Loss, and Return to Dialysis

BACKGROUND

Cancer incidence and mortality may change with varying kidney allograft function and after graft loss. We aimed to quantify cancer incidence and mortality during periods with a functioning graft and after graft loss.

METHODS

We included all adult Australians aged 20 and above who commenced kidney replacement therapy between 1982 and 2014 using data from Australia and New Zealand Dialysis and Transplant Registry. We calculated the standardized incidence ratios and standardized mortality ratios (standardized against the Australian general population) for dialysis patients and transplant recipients during periods with a functioning graft and after graft loss.

RESULTS

A total of 44 765 dialysis patients without transplants, 13 443 with first kidney transplants, 2951 after first graft loss, 1010 with second transplants, and 279 after second graft loss were followed for 274 660 patient-years. Cancer incidence and mortality (per 100 000 patient-years) were 1564 and 760 in dialysis patients, 1564 and 689 in recipients of first transplants, 1188 and 390 after first graft loss, 1525 and 693 after second transplants, and 1645 and 779 after second graft loss. Cancer standardized incidence ratios and standardized mortality ratios (95% confidence intervals) were 1.15 (1.11-1.20) and 1.29 (1.21-1.36) for dialysis patients, 2.03 (1.94-2.13) and 2.50 (2.33-2.69) for recipients following their first transplant, 1.55 (1.29-1.85) and 1.40 (1.00-1.90) after first graft loss, 2.18 (1.79-2.63) and 3.00 (2.23-3.96) for second transplants, 2.59 (1.56-4.04) and 3.82 (1.75-7.25) after second graft loss.

CONCLUSIONS

In kidney transplant recipients, cancer incidence and mortality are highest during periods with a functioning graft and remained higher than in the general population even after graft loss.

Sex Disparity in Cause-Specific and All-Cause Mortality Among Incident Dialysis Patients

RATIONALE & OBJECTIVE

Early mortality rates of female patients receiving dialysis have been, at times, observed to be higher than rates among male patients. The differences in cause-specific mortality between male and female incident dialysis patients with kidney failure are not well understood and were the focus of this study.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Incident patients who had initiated dialysis in Australia and New Zealand in 1998-2018.

EXPOSURE

Sex.

OUTCOMES

Cause-specific and all-cause mortality while receiving dialysis, censored for kidney transplant.

ANALYTICAL APPROACH

Adjusted cause-specific proportional hazards models, focusing on the first 5 years following initiation of dialysis.

RESULTS

Among 53,414 patients (20,876 [39%] female) followed for a median period of 2.8 (IQR, 1.3-5.2) years, 27,137 (51%) died, with the predominant cause of death attributed to cardiovascular disease (18%), followed by dialysis withdrawal (16%). Compared with male patients, female patients were more likely to die in the first 5 years after dialysis initiation (adjusted hazard ratio [AHR], 1.08 [95% CI, 1.05-1.11]). Even though female patients experienced a lower risk of cardiovascular disease-related mortality (AHR, 0.93 [95% CI, 0.89-0.98]) than male patients, they experienced a greater risk of infection-related (AHR, 1.20 [95% CI, 1.10-1.32]) and dialysis withdrawal-related (AHR, 1.19 [95% CI, 1.13-1.26]) mortality.

LIMITATIONS

Possibility of residual and unmeasured confounders.

CONCLUSIONS

Compared with male patients, female patients had a higher risk of all-cause mortality in the first 5 years after dialysis initiation, a difference driven by higher rates of mortality from infections and dialysis withdrawals. These findings may inform the study of sex differences in mortality in other geographic settings.

Cancer Mortality in People Receiving Dialysis for Kidney Failure: An Australian and New Zealand Cohort Study, 1980-2013

RATIONALE & OBJECTIVE

Cancer is a significant cause of morbidity in the population with kidney failure; however, cancer mortality in people undergoing dialysis has not been well described. We sought to compare cancer mortality in people on dialysis for kidney failure with cancer mortality in the general population.

STUDY DESIGN

A retrospective cohort study using linked health-administrative and dialysis registry data.

SETTING & PARTICIPANTS

All people receiving dialysis represented in the Australian and New Zealand Dialysis and Transplantation Registry, 1980-2013.

EXPOSURE

Dialysis; hemodialysis (HD) and peritoneal dialysis (PD).

OUTCOME

Death and underlying cause of death ascertained using health administrative data and classified using International Classification of Diseases, Tenth Revision, Australian Modification (ICD-10-AM) codes.

ANALYTICAL APPROACH

Indirect standardization on age at death, sex, year, and country to estimate standardized mortality ratios (SMR).

RESULTS

Over 269,598 person years of observation, 34,100 deaths occurred among 59,648 people on dialysis, including 3,677 cancer deaths. The relative risk of all-site cancer death in dialysis was twice (SMR, 2.4 [95% CI, 2.33-2.49]) that of the general population and highest for oral and pharynx cancers (SMR, 24.3 [95% CI, 18.0-31.5]) and multiple myeloma (SMR, 22.5 [95% CI, 20.3-23.9]). Women on dialysis had a significantly higher risk of all-site cancer mortality (SMR, 2.7 [95% CI, 2.59-2.89]) compared with men (SMR, 2.3 [95% CI, 2.17-2.36]) (P < 0.001). People on HD (SMR, 2.2 [95% CI, 2.11-2.30]) experienced greater excess deaths from all-site cancer compared with people on PD (SMR, 1.3 [95% CI, 1.23-1.44]). Excess deaths have gradually decreased over time for all-site, multiple myeloma, and kidney cancers (P < 0.001) but have not kept up with improvements in the general population. By contrast, among people receiving dialysis, excess deaths increased for colorectal and lung cancers (P < 0.001).

LIMITATIONS

Confirmation of cancer diagnoses and population incidence data were not available; inability to exclude pre-existing cancers.

CONCLUSIONS

People on dialysis experience excess all-site and site-specific cancer mortality compared with the general population. Mortality differs by modality type, age, and sex. Understanding the role of kidney failure and other morbidities in the treatment of cancer is important for shared decision-making regarding cancer treatments and identifying potential approaches to improve outcomes.

Excess all-cause and cause-specific mortality for people with diabetes and end-stage kidney disease

AIMS

Excess mortality is high in the setting of diabetes and end-stage kidney disease (ESKD), but the effects of ESKD beyond diabetes itself remains incompletely understood. We examined excess mortality in people with diabetes with versus without ESKD, and variation by age, sex and diabetes type.

METHODS

This study included 63,599 people with type 1 (aged 20-69 years; 56% men) and 1,172,160 people with type 2 diabetes (aged 30+ years; 54% men), from the Australian National Diabetes Services Scheme. Initiation of renal replacement therapy and mortality outcomes were obtained via linkage to the Australia and New Zealand Dialysis and Transplant Registry and the National Death Index, respectively. Excess mortality was measured by calculating the mortality rate ratio (MRR) for people with versus without ESKD via indirect standardisation.

RESULTS

A total of 9027 people developed ESKD during 8,601,522 person-years of follow-up. Among people with type 1 diabetes, the MRR was 34.9 (95%CI: 16.6-73.1) in men and 41.5 (20.8-83.1) in women aged 20-29 years and was 5.6 (4.5-7.0) and 7.4 (5.5-10.1) in men and women aged 60-69 years, respectively. In type 2 diabetes, MRRs were 16.6 (8.6-31.8) and 35.8 (17.0-75.2) at age 30-39 years and were 2.8 (2.6-3.1) and 3.6 (3.2-4.1) at age 80+ years in men and women, respectively. Excess cause-specific mortality was highest for peripheral artery disease, cardiac arrest, and infections, and lowest for cancer.

CONCLUSIONS

Among people with diabetes, excess mortality in ESKD is much higher at younger ages and is higher for women compared with men.

Causes of Death in End-Stage Kidney Disease: Comparison between the United States Renal Data System and a Large Integrated Health Care System

INTRODUCTION

Using a large diverse population of incident end-stage kidney disease (ESKD) patients from an integrated health system, we sought to evaluate the concordance of causes of death (CODs) between the underlying COD from the United States Renal Data System (USRDS) registry and CODs obtained from Kaiser Permanente Southern California (KPSC).

METHODS

A retrospective cohort study was performed among incident ESKD patients who had mortality records and CODs reported in both KPSC and USRDS databases between January 1, 2007, and December 31, 2016. Underlying CODs reported by the KPSC were compared to the CODs reported by USRDS. Overall and subcategory-specific COD agreements were assessed using Cohen's weighted kappa statistic (95% CI). Proportions of positive and negative agreement were also determined.

RESULTS

Among 4,188 ESKD patient deaths, 4,118 patients had CODs recorded in both KPSC and USRDS. The most common KPSC CODs were circulatory system diseases (35.7%), endocrine/nutritional/metabolic diseases (24.2%), genitourinary diseases (12.9%), and neoplasms (9.6%). Most common USRDS CODs were cardiac disease (46.9%), withdrawal from dialysis (12.6%), and infection (10.1%). Of 2,593 records with causes listed NOT as "Other," 453 (17.4%) had no agreement in CODs between the USRDS and the underlying, secondary, tertiary, or quaternary causes recorded by KPSC. In comparing CODs recorded within KPSC to the USRDS, Cohen's weighted kappa (95% CI) was 0.20 (0.18-0.22) with overall agreement of 36.4%.

CONCLUSION

Among an incident ESKD population with mortality records, we found that there was only fair or slight agreement between CODs reported between the USRDS registry and KPSC, a large integrated health care system.

Sex differences in mortality among binational cohort of people with chronic kidney disease: population based data linkage study

OBJECTIVE

To evaluate sex differences in mortality among people with kidney failure compared with the general population.

DESIGN

Population based cohort study using data linkage.

SETTING

The Australian and New Zealand Dialysis and Transplant Registry (ANZDATA), which includes all patients receiving kidney replacement therapy in Australia (1980-2019) and New Zealand (1988-2019). Data were linked to national death registers to determine deaths and their causes, with additional details obtained from ANZDATA.

PARTICIPANTS

Of 82 844 people with kidney failure, 33 329 were female (40%) and 49 555 were male (60%); 49 376 deaths (20 099 in female patients; 29 277 in male patients) were recorded over a total of 536 602 person years of follow-up.

MAIN OUTCOME MEASURES

Relative measures of survival, including standardised mortality ratios, relative survival, and years of life lost, using general population data to account for background mortality (adjusting for country, age, sex, and year). Estimates were stratified by dialysis modality (haemodialysis or peritoneal dialysis) and for the subpopulation of kidney transplant recipients.

RESULTS

Few differences in outcomes were found between male and female patients with kidney failure. However, compared with the general population, female patients with kidney failure had greater excess all cause deaths than male patients (female patients: standardised mortality ratio 11.3, 95% confidence interval 11.2 to 11.5, expected deaths 1781, observed deaths 20 099; male patients: 6.9, 6.8 to 6.9, expected deaths 4272, observed deaths 29 277). The greatest difference was observed among younger patients and those who died from cardiovascular disease. Relative survival was also consistently lower in female patients, with adjusted excess mortality 11% higher (95% confidence interval 8% to 13%). Average years of life lost was 3.6 years (95% confidence interval 3.6 to 3.7) greater in female patients with kidney failure compared with male patients across all ages. No major differences were found in mortality by sex for haemodialysis or peritoneal dialysis. Kidney transplantation reduced but did not entirely remove the sex difference in excess mortality, with similar relative survival (P=0.83) and years of life lost difference reduced to 2.3 years (95% confidence interval 2.2 to 2.3) between female and male patients.

CONCLUSIONS

Compared with the general population, female patients had greater excess deaths, worse relative survival, and more years of life lost than male patients, however kidney transplantation reduced these differences. Future research should investigate whether systematic differences exist in access to care and possible strategies to mitigate excess mortality among female patients.

National and international kidney failure registries: characteristics, commonalities, and contrasts

Registries are essential for health infrastructure planning, benchmarking, continuous quality improvement, hypothesis generation, and real-world trials. To date, data from these registries have predominantly been analyzed in isolated "silos," hampering efforts to analyze "big data" at the international level, an approach that provides wide-ranging benefits, including enhanced statistical power, an ability to conduct international comparisons, and greater capacity to study rare diseases. This review serves as a valuable resource to clinicians, researchers, and policymakers, by comprehensively describing kidney failure registries active in 2021, before proposing approaches for inter-registry research under current conditions, as well as solutions to enhance global capacity for data collaboration. We identified 79 kidney-failure registries spanning 77 countries worldwide. International Society of Nephrology exemplar initiatives, including the Global Kidney Health Atlas and Sharing Expertise to support the set-up of Renal Registries (SharE-RR), continue to raise awareness regarding international healthcare disparities and support the development of universal kidney-disease registries. Current barriers to inter-registry collaboration include underrepresentation of lower-income countries, poor syntactic and semantic interoperability, absence of clear consensus guidelines for healthcare data sharing, and limited researcher incentives. This review represents a call to action for international stakeholders to enact systemic change that will harmonize the current fragmented approaches to kidney-failure registry data collection and research.

Survival and transplant outcomes among young children requiring kidney replacement therapy

BACKGROUND

Young children starting kidney replacement therapy (KRT) suffer high disease burden with unique impacts on growth and development, timing of transplantation and long-term survival. Contemporary long-term outcome data and how these relate to patient characteristics are necessary for shared decision-making with families, to identify modifiable risk factors and inform future research.

METHODS

We examined outcomes of all children ≤ 5 years enrolled in the Australia and New Zealand Dialysis and Transplant Registry, commencing KRT 1980-2017. Primary outcomes were patient and graft survival. Final height attained was also examined. We used generalized additive modelling to investigate the relationship between age and graft loss over time post-transplant.

RESULTS

In total, 388 children were included, of whom 322 (83%) received a kidney transplant. Cumulative 1-, 5- and 10-year patient survival probabilities were 93%, 86% and 83%, respectively. Death censored graft survival at 1, 5 and 10 years was 93%, 87% and 77%, respectively. Most children were at least 10 kg at transplantation (n = 302; 96%). A non-linear relationship between age at transplantation and graft loss was observed, dependent on time post-transplant, with increased risk of graft loss among youngest recipients both initially following transplantation and subsequently during adolescence. Graft and patient survival have improved in recent era.

CONCLUSIONS

Young children commencing KRT have good long-term survival and graft outcomes. Early graft loss is no reason to postpone transplantation beyond 10 kg, and among even the youngest recipients, late graft loss risk in adolescence remains one of the greatest barriers to improving long-term outcomes.

Keratinocyte Cancer Mortality in Kidney Transplant Recipients

BACKGROUND

Kidney transplant recipients are at increased risk of developing and dying from keratinocyte cancer. Risk factors for keratinocyte cancer death have not been previously described.

METHODS

In a cohort of kidney transplant recipients transplanted in Queensland 1995-2014, we identified keratinocyte cancer deaths by searching national transplant and state death registries to March 2020. Standardized keratinocyte cancer mortality rates and mortality ratios were calculated. We used a competing risks model to identify factors associated with keratinocyte cancer death and calculated relative risks (RRs) and 95% confidence intervals (CIs).

RESULTS

There were 562 deaths in 1866 kidney transplant recipients (62% males; 86% Caucasian) with 25 934 person-years of follow-up, of which 36 were due to squamous cell carcinoma (SCC) and 1 to basal cell carcinoma (BCC) with standardized mortality rates of 78 (95% CI 53-111) and 2 (95% CI 0.1-11) per 100,000 person-years respectively. The standardized mortality ratio for keratinocyte cancer was 23 (95% CI 23-24). Besides Caucasian ethnicity (associated with 100% of keratinocyte cancer deaths), male sex (RR 3.24 95% CI 1.26-8.33), and older age at transplantation (≥ 50 versus <50 years RR 3.09 95% CI 1.38-6.89) were associated with increased risk of keratinocyte cancer death.

CONCLUSIONS

Keratinocyte cancer mortality in kidney transplant recipients is over 20 times higher than in the general population. Most keratinocyte cancer deaths are due to cutaneous SCC, however, BCC can be fatal. Education in skin cancer prevention is essential to avoid unnecessary deaths from keratinocyte cancer amongst kidney transplant recipients.

Incidence and predictors of vascular events following end-stage kidney disease in childhood

AIM

Cardiovascular death is a leading cause of mortality in paediatric end-stage kidney disease (ESKD). There is however little known about the clinically relevant vascular disease in this population. We aimed to describe the incidence of new onset vascular disease and vascular death in Australian children receiving renal replacement therapy (RRT). We also aimed to identify demographic or childhood risk factors for these endpoints, and whether vascular disease predicts mortality.

METHODS

Data on Australian patients who commenced RRT at <18 years of age from 1991 to 2017 were extracted from the Australian and New Zealand Dialysis and Transplant Registry (ANZDATA). Multivariable competing risks regression was used to identify factors associated with vascular events.

RESULTS

A cohort of 1268 patients were followed up for a median of 10.31 years. Vascular disease was reported in 5.4%, and vascular death in 4.1%. The cumulative incidence of any vascular event, that is, disease or death, at 10 and 20 years was 5.5% and 12.8%, respectively. Childhood vascular events were associated with non-Caucasian, non-Indigenous ethnicity, and for the 804 patients followed up after 18 years of age, vascular events were associated with lack of childhood transplantation, longer childhood dialysis duration and Indigenous ethnicity. Vascular disease was only reported for 25.49% of patients who had a vascular death, and although a significant risk factor for mortality, it had limited ability to predict mortality.

CONCLUSION

Cumulative incidence of vascular events is significant after commencing RRT during childhood and is associated with ethnicity, longer childhood dialysis duration and lack of childhood transplantation.

Death after Kidney Transplantation: An Analysis by Era and Time Post-Transplant

BACKGROUND

Mortality risk after kidney transplantation can vary significantly during the post-transplant course. A contemporary assessment of trends in all-cause and cause-specific mortality at different periods post-transplant is required to better inform patients, clinicians, researchers, and policy makers.

METHODS

We included all first kidney-only transplant recipients from 1980 through 2018 from the Australia and New Zealand Dialysis and Transplant Registry. We compared adjusted death rates per 5-year intervals, using a piecewise exponential survival model, stratified by time post-transplant or time post-graft failure.

RESULTS

Of 23,210 recipients, 4765 died with a functioning graft. Risk of death declined over successive eras, at all periods post-transplant. Reductions in early deaths were most marked; however, recipients ≥10 years post-transplant were 20% less likely to die in the current era compared with preceding eras (2015-2018 versus 2005-2009, adjusted hazard ratio, 0.80; 95% confidence interval, 0.69 to 0.90). In 2015-2018, cardiovascular disease was the most common cause of death, particularly in months 0-3 post-transplant (1.18 per 100 patient-years). Cancer deaths were rare early post-transplant, but frequent at later time points (0.93 per 100 patient-years ≥10 years post-transplant). Among 3657 patients with first graft loss, 2472 died and were not retransplanted. Death was common in the first year after graft failure, and the cause was most commonly cardiovascular (50%).

CONCLUSIONS

Reductions in death early and late post-transplant over the past 40 years represent a major achievement. Reductions in cause-specific mortality at all time points post-transplant are also apparent. However, relatively greater reductions in cardiovascular death have increased the prominence of late cancer deaths.

Survival after Kidney Transplantation during Childhood and Adolescence

BACKGROUND AND OBJECTIVES

Survival in pediatric kidney transplant recipients has improved over the past five decades, but changes in cause-specific mortality remain uncertain. The aim of this retrospective cohort study was to estimate the associations between transplant era and overall and cause-specific mortality for child and adolescent recipients of kidney transplants.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data were obtained on all children and adolescents (aged <20 years) who received their first kidney transplant from 1970 to 2015 from the Australian and New Zealand Dialysis and Transplant Registry. Mortality rates were compared across eras using Cox regression, adjusted for confounders.

RESULTS

A total of 1810 recipients (median age at transplantation 14 years, 58% male, 52% living donor) were followed for a median of 13.4 years. Of these, 431 (24%) died, 174 (40%) from cardiovascular causes, 74 (17%) from infection, 50 (12%) from cancer, and 133 (31%) from other causes. Survival rates improved over time, with 5-year survival rising from 85% for those first transplanted in 1970-1985 (95% confidence interval [95% CI], 81% to 88%) to 99% in 2005-2015 (95% CI, 98% to 100%). This was primarily because of reductions in deaths from cardiovascular causes (adjusted hazard ratio [aHR], 0.25; 95% CI, 0.08 to 0.68) and infections (aHR, 0.16; 95% CI, 0.04 to 0.70; both for 2005-2015 compared with 1970-1985). Compared with patients transplanted 1970-1985, mortality risk was 72% lower among those transplanted 2005-2015 (aHR, 0.28; 95% CI, 0.18 to 0.69), after adjusting for potential confounders.

CONCLUSIONS

Survival after pediatric kidney transplantation has improved considerably over the past four decades, predominantly because of marked reductions in cardiovascular- and infection-related deaths.

Cancer mortality in kidney transplant recipients: An Australian and New Zealand population-based cohort study, 1980-2013

Cancer burden is increasing in kidney transplant recipients, but differences in mortality compared to the general population remain unclear. We sought to compare cancer mortality in paediatric and adult kidney transplant recipients with the general population and describe any differences, by site, age and sex, country and over time. We included kidney transplant recipients from the Australian and New Zealand Dialysis and Transplantation Registry, 1980-2013. Date of death and underlying cause of death were ascertained by data-linkage and classified using ICD10AM codes. Indirect standardisation was used to estimate standardised mortality ratios (SMR). There were 5,284 deaths in 17,628 kidney transplant recipients over 175,084 person-years of observation, including 1,061 (20%) cancer deaths. Relative cancer mortality was higher than the general population for all-site (SMR 2.9, 95% CI 2.7-3.1) cancer and highest for nonmelanoma skin cancer (SMR 50.9, 95% CI 43.5-59.6) and lymphoma (SMR 42.2, 95% CI 35.3-50.5). Relative cancer mortality decreased with increasing age in men (p < 0.001) and women (p = 0.001) but never reached parity with the general population. Relative mortality did not change with age for skin and lip, or colorectal cancers (p-value >0.1). Only relative colorectal cancer mortality increased over time (p = 0.002). Our study shows cancer mortality in kidney transplant recipients was higher than expected in the general population. The magnitude of excess mortality varied by cancer site, age and sex. Further evidence is needed to identify whether this variation is due to differences at diagnosis or access and effectiveness of cancer treatments in this population.

Overall and Site-Specific Cancer Mortality in Patients on Dialysis and after Kidney Transplant

Background Patients with ESRD have a substantially increased cancer risk, but few studies have examined the patterns of cancer mortality along a patient's journey from dialysis to transplantation.

METHODS

We identified all Australian patients on dialysis and patients with transplants from 1980 to 2014 from the Australia and New Zealand Dialysis and Transplant Registry. Using standardized mortality ratios (SMRs), we compared cancer mortality among patients on dialysis and patients with transplants versus the general population (overall and by age, sex, year, and site); we also performed a subgroup analysis excluding patients with preexisting cancers.

RESULTS

We followed 52,936 patients on dialysis and 16,820 transplant recipients for 170,055 and 128,352 patient-years, respectively. There were 2739 cancer deaths among patients on dialysis and 923 cancer deaths among transplant recipients. Overall, cancer SMRs were 2.6 for patients on dialysis and 2.7 for transplant recipients. For patients on dialysis, SMRs were highest for multiple myeloma (30.5), testicular cancer (17.0), and kidney cancer (12.5); for transplant recipients, SMRs were highest for non-Hodgkin lymphoma (10.7), kidney cancer (7.8), and melanoma (5.8). Some 61.0% of patients on dialysis and 9.6% of transplant recipients who experienced cancer death had preexisting cancer. The SMRs for de novo cancer was 1.2 for patients on dialysis and 2.6 for transplant recipients.

CONCLUSIONS

Patients on dialysis and transplant recipients experienced >2.5-fold increased risk of cancer death compared with the general population. This increased risk was largely driven by preexisting cancers in patients on dialysis and de novo cancers in patients with transplants.