Differential association of body mass index with access to kidney transplantation in men and women

Background and objectives: Obese patients encounter barriers to medical care not encountered by lean patients, and inequities in access to care among obese patients may vary by sex. This study aimed to determine the association of body mass index (BMI) with access to kidney transplantation in men and women. Design, setting, participants, & measurements: In this retrospective analysis of 702,456 incident ESRD patients aged 18-70 years (captured in the US Renal Data System between 1995 and 2007), multivariate time-to-event analyses were used to determine the association of BMI with likelihood of transplantation from any donor source, transplantation from a living donor, and transplantation from a deceased donor, as well the individual steps in obtaining a deceased donor transplant (activation to the waiting list, and transplantation after wait-listing). Results: Among women, a BMI≥25.0 kg/m² was associated with a lower likelihood of transplantation from any donor source (hazard ratio [HR], 0.75; 95% confidence interval [95% CI], 0.73 to 0.77), transplantation from a living donor (HR, 0.75; 95% CI, 0.72 to 0.77), and transplantation from a deceased donor (HR, 0.74; 95% CI, 0.72 to 0.77). By contrast, among men, a BMI of 25.0-34.9 kg/m² was associated with a higher likelihood of the outcomes of transplantation from any donor source (HR, 1.08; 95% CI, 1.06 to 1.11), transplantation from a living donor (HR, 1.18; 95% CI, 1.13 to 1.22), and transplantation from a deceased donor (HR, 1.05; 95% CI, 1.02 to 1.07). Among men, the level beyond which BMI was associated with a lower likelihood of transplantation from any donor source or a living donor was ≥40.0 kg/m², and ≥35.0 kg/m² in the case of deceased donor transplantation. Conclusions: The association of BMI with access to transplantation varies between men and women. The reasons for this difference should be further studied.