Sex disparities in mortality among patients with kidney failure receiving dialysis

Abstract

Females are known to have a better survival rate than males in the general population, but previous studies have shown that this superior survival is diminished in patients on dialysis. This study aimed to investigate the risk of mortality in relation to sex among Korean patients undergoing hemodialysis (HD) or peritoneal dialysis (PD). A total of 4994 patients with kidney failure who were receiving dialysis were included for a prospective nationwide cohort study. Cox multivariate proportional hazard models were used to determine the association between sex and the risk of cause-specific mortality according to dialysis modality. During a median follow-up of 5.8 years, the death rate per 100 person-years was 6.4 and 8.3 in females and males, respectively. The female-to-male mortality rate in patients on dialysis was 0.77, compared to 0.85 in the general population. In adjusted analyses, the risk of all-cause mortality was significantly lower for females than males in the entire population (hazard ratio [HR] 0.79, 95% confidence interval [CI] 0.71-0.87, P < 0.001). No significant differences in the risk of cardiovascular and infection-related deaths were observed according to sex. The risk of mortality due to sudden death, cancer, other, or unknown causes was significantly lower for females than males in the entire population (HR 0.66, 95% CI 0.56-0.78, P < 0.001), in patients on HD (HR 0.75, 95% CI 0.62-0.90, P = 0.003), and in patients on PD (HR 0.49, 95% CI 0.34-0.70, P < 0.001). The survival advantage of females in the general population was maintained in Korean dialysis patients, which was attributed to a lower risk of noncardiovascular and noninfectious death.Trial registration: ClinicalTrials.gov Identifier: NCT00931970.

Figure 1

Flow chart of participant inclusion. Among a total of 5244 incident and prevalent patients receiving dialysis, 63 patients who died within 90 days of dialysis initiation, 7 patients undergoing both hemodialysis (HD) and peritoneal dialysis (PD), and 180 patients with inadequate information for analysis were excluded. Thus, a total of 3284 patients on HD and 1710 patients on PD were included in this study.

Figure 2

Death event rates per 100 person-years in male and female patients according to dialysis modality. The rate was 6.4 in females and 8.3 in males in the entire population, 6.9 in females and 8.2 in males in the hemodialysis (HD) population, and 5.4 in females and 8.6 in males in the peritoneal dialysis (PD) population.

Figure 3

Cumulative incidence curve for deaths in male and female patients according to dialysis modality. (A–C) Male patients had significantly more all-cause death events and (D–F) noncardiovascular and noninfectious death events than female patients in the entire population, hemodialysis (HD) population, and peritoneal dialysis (PD) population.

Figure 4

(A) Analysis of sex interaction in the associations between patient characteristics and all-cause or (B) noncardiovascular and noninfectious death. The risk of all-cause mortality associated with diabetes was higher in female patients on peritoneal dialysis (PD) than male patients on PD (interaction P = 0.033). The risk of noncardiovascular and noninfectious death associated with diabetes was higher in female patients on PD than in male patients on PD (interaction P = 0.045).