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Study Explores Mortality and Years of Life Lost in Children with Kidney Failure

Tracy Hampton
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Children who develop kidney failure and receive a kidney transplant have excellent 5- and 10-year survival rates, but little is known about their lifetime survival. In research recently published in JASN, investigators assessed mortality rates in a population-based study of children with kidney failure in Australia and New Zealand and quantified the years of life lost (YLL) due to kidney failure in childhood (1). “Quantification of YLL would aid clinicians in their discussions with parents and caregivers about the future of a child with kidney failure,” the authors wrote. “It would also assist policy makers who use expected length of life in conjunction with quality of life to support funding and policy decisions.”

When the investigators developed a model that mirrors the lived experience of children with kidney failure, who typically transition between dialysis and transplant and back again before death, they found that YLL were substantially higher than those for patients with many other chronic diseases that develop in childhood.

Their model involved patient data from the CELESTIAL study, a binational, population-based cohort study of all people with treated kidney failure in both Australia (1980–2019) and New Zealand (1988–2019) listed in the Australia and New Zealand Dialysis and Transplant Registry. Patient data in the CELESTIAL study were linked to national death registers to determine the date and cause of death.

Among the 2013 children identified with incident kidney failure, there were 394 deaths (20%) over 30,082 person-years of follow-up with a median follow-up of 13.1 years. Overall, 288 children (14%) underwent preemptive kidney transplantation, and 1497 (74%) underwent kidney transplantation after a median 1.1 years on dialysis. A total of 228 (11%) were never transplanted.

Most patients were older than 10 years of age at the time of kidney failure diagnosis (61%), and the most common cause of kidney failure was congenital anomalies of the kidney and urinary tract (39%), followed by glomerulonephritis (34%), cystic kidney diseases (10%), and other causes (17%). The median number of treatment transitions (moving from dialysis to transplant or vice versa) was 2, and most children (71%) spent more than half of their follow-up time with a functioning transplant. The greatest probability of death was during treatment with dialysis.

Compared with the general population, excess deaths among patients were 41 times higher than expected during 1980–1984 and fell to 22 times higher during 1995–1999 and then to 17 times higher during 2015–2019. Among patients who received transplants, excess deaths were 23 times higher than expected in 1980–1984. This fell to 16 times during 1995–1999 and then to 13 times during 2015–2019. Mortality rates were 12.2 per 1000 person-years in male patients and 14.3 per 1000 person-years in female patients. Mortality rates were highest in the first 3–6 months after kidney failure (34.5 per 1000 person-years), and mortality rates for those younger than 2 years old when diagnosed with kidney failure were 7.5 times the rate of those aged 2–5 years, 39 times the rate of those aged 11–14 years, and 10 times the rate of those aged 15 years or older.

YLL were higher with younger age at kidney failure diagnosis and in female patients. For those who were 5 years old when diagnosed with kidney failure, YLL were 29.6 years in female patients and 21.3 years in male patients. When aged 15 years at the time of kidney failure diagnosis, YLL were 25.0 years in female patients and 17.3 years in male patients. YLL were higher for those diagnosed in 1980–1998 than in those diagnosed in 1999–2019. Children diagnosed with kidney failure in the contemporary era had an extra 5.8 years of life compared with those in the historical era; however, females experienced less improvement in their YLL than males, widening the preexisting sex disparity.

The study's investigators found that although females tend to outlive males in the general population, the opposite appears to occur among individuals diagnosed with kidney failure as children. Sex disparities in the treatment and outcomes of kidney diseases may be involved—for example, it is known that women with kidney failure are less likely to receive transplants than men. Indeed, in this study, female pediatric patients had less access to transplantation, particularly preemptive transplantation, than did male patients. Differences in hormones, immune function, and donor and recipient size may also play a role in sex differences in kidney transplant outcomes.

[A]lthough females tend to outlive males in the general population, the opposite appears to occur among individuals diagnosed with kidney failure as children.

The study adds to other research, including a study from the US Renal Data System, which calculated that for American children with kidney failure, the expected YLL are 40–55 years if treated with dialysis and 12–20 years if treated with transplantation; however, dialysis and transplantation were considered separately and not as part of a treatment continuum (2).

“The key findings of our study were (1) kidney failure in childhood was associated with substantial YLL, ranging from 16 to 32 years depending on age at kidney failure and sex; (2) female patients lose ≥7 more life years than male patients irrespective of age at diagnosis; and (3) while the excess mortality rate in children with kidney failure remains extremely high, it has been improving over time,” the authors wrote. They stressed that despite the potential YLL, many children and adolescents with kidney failure enjoy numerous life years ahead of them, allowing them to participate in important life events—from completing their education, to raising a family, to attaining professional goals.

“This study offers hope to patients and their families that children with kidney failure can grow up and reach significant life milestones. We need more research on how to help these children transition through the different stages of life successfully with kidney disease and how to better support their life participation at all ages,” said lead author Melanie L. Wyld, MBBS, MBA, MPH, PhD, FRACP, a kidney and transplant physician at The University of Sydney and Westmead Hospital, in New South Wales.