Sex Differences in Mortality Among People with End-Stage Kidney Disease: Bi-National Data-Linkage Cohort Study

Abstract

Introduction Female life expectancies consistently exceed males in the general population. Yet, this survival advantage may not persist in the presence of a chronic disease due to biological differences or healthcare inequities. Objectives and Approach We aimed to explore sex differences in mortality among people with end-stage kidney disease (ESKD). T he entire ESKD population in Australia, 1980-2013, and New Zealand,1988-2012, were included from the Australian and New Zealand Dialysis and Transplant Registry. Data linkage to national death registers was undertaken to ascertain deaths and their causes. We estimated relative measures of survival, including standardized mortality ratios (SMR), relative survival and expected life years lost, using general population data to account for background mortality, adjusting for country, age, sex and year. Results Of 60,823 ESKD patients, there were 25,042 females (41%) and 35,781 males (59%). Mortality sex differences within the ESKD population were minor, but once compared to the general population, female ESKD patients had more excess deaths, worse relative survival and greater life years lost compared to male ESKD patients. Females had 11.5 SMR (95%CI:11.3-11.7) and males had 6.7 SMR (95%CI:6.7-6.8), with greater disparity among younger ages and from certain causes. Relative survival was consistently lower in females, with adjusted excess mortality 9% higher (95%CI:7-12%) in ESKD females. Average life years lost was 4-5 years greater in ESKD females compared to males across all ages. Kidney transplantation reduced the sex differences in excess mortality, with similar relative survival (p=0.42) and average life years lost reduced to 3-4 years for females. Conclusion / Implications The impact of ESKD is more profound for women than men with greater excess mortality, however kidney transplantation attenuates these differences. Our findings show that chronic diseases and sex can compound to produce worse outcomes where women lose their survival advantage in the presence of ESKD.