Is there sex disparity in vascular access at dialysis initiation in France? A mediation analysis using data from the Renal Epidemiology and Information Network registry.

Background: This study was conducted to estimate the direct effect of sex on the proportion of hemodialysis (HD) catheters used at dialysis initiation and to investigate whether predialysis care or socioeconomic status acted as a mediator of the sex effect. Methods: Patients who started dialysis between January 1, 2017, and June 30, 2018, in France were included using the data of the Renal Epidemiology and Information Network (REIN) registry. We performed logistic regression to study the association between sex and the proportion of HD catheters used. A mediation analysis with a counterfactual approach was carried out to evaluate whether there was an indirect effect of sex through the proxies of predialysis care {hemoglobin, albumin levels, glomerular filtration rate [GFR] at dialysis initiation} and socioeconomic status. Because an interaction between sex and social deprivation has been identified, we performed a subgroup analysis on deprived and nondeprived patients. Results: The study included 16 032 patients, and the sex ratio (male to female) was 10 405:5627. In the multivariable analysis, women were associated with a greater risk of starting dialysis with a catheter {odds ratio [OR], 1.32 [95% confidence interval (CI): 1.23-1.42]}. There was an indirect effect of sex on the proportion of HD catheters through proxies for predialysis care {albuminemia <30 g/L [OR, 1.08 (95% CI: 1.05-1.10)], hemoglobin <11 g/dL [OR, 1.03 (95% CI: 1.02-1.04)], glomerular filtration rate <7 mL/min [OR, 1.05 (95% CI: 1.04-1.07)]}. Among deprived patients, there was no direct effect of sex on catheter proportion. Conclusions: Women were associated with a higher risk of starting dialysis through an HD catheter. The effect of sex was mediated by predialysis care, particularly for deprived patients.