Sex Disparities in Risk of Mortality Among Children With ESRD

Abstract

Rationale & objective: In the general population, girls have lower mortality risk compared with boys. However, few studies have focused on sex differences in survival and in access to kidney transplantation among children with end-stage kidney disease.

Study design: Retrospective cohort study.

Setting & participants: Children aged 2 to 19 years registered in the US Renal Data System who started renal replacement therapy (RRT) between 1995 and 2011.

Predictor: Study participant sex.

Outcome: Time to death and time to kidney transplantation.

Analytical approach: We used adjusted Cox models to examine the association between sex and all-cause mortality. We used Fine-Gray models to examine the association between sex and kidney transplantation accounting for the competing risk for death.

Results: We included 14,024 children, of whom 1,880 died during a median 7.1 years of follow-up. In adjusted analyses, the HR for death was higher for girls (HR, 1.36; 95% CI, 1.25-1.50) than boys. When we further adjusted our survival models for transplantation as a time-dependent covariate, the hazard rate of death in girls was partially attenuated but remained statistically significantly higher than that for boys (HR, 1.28; 95% CI, 1.17-1.41). Girls were also less likely to receive a kidney transplant than boys (adjusted subdistribution HR, 0.91; 95% CI, 0.88-0.95) in analyses treating death as a competing risk.

Limitations: Lack of data for disease course before the onset of RRT and observational study data.

Conclusions: The mortality rate was substantially higher for girls than for boys treated with RRT. Access to transplantation was lower for girls than boys, but differences in transplantation access accounted for only a small proportion of the survival differences by sex.

Keywords: Pediatric nephrology; RRT modality; boy; children; end-stage renal disease (ESRD); girl; incident ESRD; kidney transplant; mortality; mortality risk; renal replacement therapy (RRT); sex disparity; transplantation access.