Mortality Rates in Children Treated with Maintenance Peritoneal Dialysis

Children with kidney failure are commonly treated with maintenance peritoneal dialysis, performed at home by the patient’s adult caregivers. Peritoneal dialysis is the preferred modality in children due to its applicability across the pediatric age range and compatibility with schooling and social life. However, according to Sophie Ploos van Amstel, MD, and colleagues, the successful implementation of maintenance peritoneal dialysis is a challenging therapy, one that is subject to significant patient morbidity and mortality.

To date, research on pediatric kidney replacement therapy (KRT) has focused primarily on Europe and North America. Survival rates appear to have improved over the past 30 years, yet annual mortality rates for children on dialysis are at least 30 times higher than in the general population. Five-year patient survival for pediatric dialysis patients is ~84% in North America and ~90% in Europe.

The International Pediatric Peritoneal Dialysis Network (IPPN) collects patient outcome data and comprehensive clinical, biochemical, and treatment information from a large cohort of children undergoing maintenance peritoneal dialysis worldwide. Results of previous studies based on the IPPN database have identified associations of patient survival with clinical and laboratory findings, and with macroeconomic factors. The researchers in the current study used IPPN data to describe (1) the current global and regional mortality risk of children treated with maintenance peritoneal dialysis, (2) the main causes of death, and (3) the macroeconomic factors that are associated with mortality risk and/or the distribution of death causes around the globe. Results were reported in the American Journal of Kidney Diseases [2021;78(3):380-390].

The prospective cohort study included patients who were <19 years of age at inclusion into the IPPN registry who initiated maintenance peritoneal dialysis between 1996 and 2017. The primary exposure of interest was region (Asia, Western Europe, Eastern Europe, Latin America, North America, and Oceania). The primary outcome of interest was all-cause maintenance peritoneal mortality.

The researchers also examined other demographic, clinical, and macroeconomic factors. They divided countries into four income groups based on gross national income (GNI): low income (<$12,000), lower-middle income ($12,000 to <$16,000), upper-middle income ($16,000 to <$45,000), and high-income (≥$45,000).

Patients were observed for 3 years and the mortality rates in the regions and income groups were calculated. Cause-specific hazards models with random effects were fit to calculate the proportional change in variance for factors that could explain variation in mortality rates.

The study included 2956 patients. Most Asian countries (56.4%) fell in the lowest GNI quartile; Latin American countries tended to have a slightly higher GNI. All countries in Western Europe fell in the higher GNI quartiles; Eastern European countries clustered within the middle quartiles. All countries in North America were classified as having a high GNI.

Median age at initiation of KRT was 7.8 years and varied between 4.9 years in Western Europe and 9.3 years in Asia. Median age at inclusion in the IPPN was 8.3 years, ranging from 5.3 years in Western Europe to 9.8 years in North America. In general, patients treated in Europe were younger than those in Asia and North America (P<.001).

CAKUT (congenital anomalies of the kidney and urinary tract) was the most frequent primary kidney disorder (46.2%), followed by glomerulopathies (27.6%). Percentages of patients with a defined syndrome were higher in North America and Eastern Europe (17.7% and 17.6%, respectively), compared with other regions. Confirmed genetic disorders were significantly less common in Latin America (4.1% vs 12.4% overall). The more frequent comorbidities were cardiac abnormalities (14.1%), cognitive dysfunction (13.8%), and motor dysfunction (11.7%). The percentages of all comorbidities, with the exception of hearing dysfunction, were markedly higher in North America (P<.001).

Overall, approximately one-third of patients had received KRT prior to initiating their current maintenance peritoneal dialysis treatment. Of those, 20.1% had received a kidney transplant and 79.9% had undergone dialysis treatment (hemodialysis, previous peritoneal dialysis, or both). Time on KRT prior to inclusion in the IPPN Registry was a median 3.0 months. On registry entry, the majority of patients were treated with automated peritoneal dialysis (75.7%), followed by continuous ambulatory peritoneal dialysis (23.5%), and other peritoneal dialysis treatment (1.6%). There were significant differences in the distribution of peritoneal dialysis among regions (P<.001); the percentage of automated peritoneal dialysis was highest in North America (95.1%).

Oceania was excluded from the survival analyses due to limited number of patients. Median follow-up duration in the IPPN Registry was 1.68 years. During follow-up, maintenance peritoneal dialysis was stopped in 1969 patients, of whom 9% (n=177) died. Other reasons for stopping maintenance peritoneal dialysis were kidney transplantation, switch to hemodialysis, and loss to follow-up assessment.

The mortality rate in North America was significantly lower than in other regions. Following adjustment for region, mortality rates were highest in low-income countries, followed by the lower-middle-income countries.

After 3 years, the probability of death in the overall cohort was 5%, ranging from 2% in North America to 9% in Eastern Europe. Results of analysis by GNI quartile demonstrated that after 3 years of follow-up assessment, patients in countries with a low GNI tended to have a higher mortality risk and a lower probability of receiving a kidney transplant.

The variance among regions was examined using cause-specific hazards models with random effects. Results demonstrated that country differences in GNI explained 50.1%, choice of modality explained 22.5%, and body mass index explained 11.1% of the variance. Other minor factors included KRT vintage (9.3%) and sex (2.4%).

Limitations to the study cited by the authors included the possibility of problems with the accuracy and quality of the data in the IPPN Registry, and the possibility of selection bias.

In conclusion, the researchers said, “This study shows that the overall 3-year patient survival on pediatric maintenance peritoneal dialysis is high, and that country income is associated with patient survival. On the other hand, the interpretation of interregional survival differences as found in this study remains complicated due to selection bias working in different directions. To reduce such bias, population-based registries are warranted.”

Takeaway Points

1. Researchers reported results of a study examining the mortality risk of children on maintenance peritoneal dialysis worldwide, as well as factors associated with patient survival.
2. At 3-years of assessment, the probability of mortality in the overall cohort was 5%, ranging from 2% in North America to 9% in Eastern Europe.
3. Mortality rates adjusted for region were highest in low-income countries, followed by lower-middle-income countries.