Effect modifiers of sex disparities in kidney transplantation referral rates among adults with end-stage kidney disease (ESKD) in the Southeastern U.S. Open Access

Smothers, Laken (Spring 2021)

Permanent URL: https://etd.library.emory.edu/concern/etds/db78td34c?locale=en


Background & Aims: Males with end-stage kidney disease (ESKD) are more likely to be referred for and receive a kidney transplant compared to females, though reasons for this disparity are unknown. In this study, we examine the role of age, race/ethnicity, and obesity as potential effect modifiers in the association between sex and kidney transplant referral rates. 

Methods: We identified all adults (18-80 years) with ESKD from the US Renal Data System in Georgia, North Carolina, and South Carolina between January 2012 and December 2015, and linked to referral data obtained from transplant centers, with follow-up through December 2016,. Using a mixed-effects multivariate Cox Proportional Hazards model adjusted for several patient-level characteristics and accounting for clustering by dialysis facility, we assessed the association between sex and 12-month referral (from dialysis initiation). Interaction terms were included for age, race/ethnicity, and body mass index (BMI), and results stratified accordingly. 

Results: Among 31,881 ESKD patients, 31.1% (n=9,928) were referred within 12-months . Overall, females were 13% less likely to be referred for a kidney transplant as compared with males in fully adjusted models (HR: 0.87; 95% CI: 0.83,0.91). Interaction terms for age, race/ethnicity, and BMI were significant. Females aged 45-64 and 65-80 were 0.90 (0.85, 0.96) and 0.75 (0.68, 0.82) less likely to be referred compared to males of the same age. Non-Hispanic White and Non-Hispanic Black females were 0.79 (0.73, 0.85) and 0.91 (0.86, 0.97) less likely to be referred compared to males of the same race/ethnicity. For all other race and age subgroups, no sex difference in referral rates was observed. For obesity, females were 9-29% less likely to be referred across all BMI groups, excluding BMI 30-34.9 where referral rates were similar in males and females.

Conclusion: In a Southeastern US population, we show that the sex disparity in referral rates appears to be specific to older, Non-Hispanic Black and White females, and most BMI groups, excluding BMI 30-34.9. Interventions to reduce sex disparities in kidney transplant referral rates should consider the potential effects of age, race/ethnicity, and obesity. 

Table of Contents

Introduction     1

Methods    4

Results     6

Discussion     8

References    14

Tables     16

Figures     20

Appendices    23

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