Effect of hemoglobin volatility on cardiovascular prognosis in peritoneal dialysis patients / 中华肾脏病杂志

ABSTRACT

Objective:To investigate the effect of hemoglobin (Hb) volatility on cardiovascular prognosis in peritoneal dialysis (PD) patients.Methods:Retrospective cohort study was designed. Patients undergoing stable PD for more than 3 months and followed up regularly for at least 1 year were enrolled from May 1, 2013 to October 31, 2014 in the General Hospital of Ningxia Medical University. According to the Hb variation based on the mean changes in Hb standard deviation at 1 month, 3 months, 6 months, 12 months over baseline Hb, all patients were divided into low volatility group (≤10 g/L), moderate volatility group (>10-20 g/L) and high volatility group (>20 g/L), and baseline information were compared among these groups. Kaplan-Meier survival analysis and Cox regression equation were used to analyze the relationship between Hb variation and cardiovascular mortality and all-cause mortality. Besides, the patients were divided into qualified group (Hb≥110 g/L) and substandard group (Hb<110 g/L) by the Hb level at the study endpoint (cardiovascular death and all-cause death) according to KDIGO guidelines and relevant literature. Cox regression analysis was used to analyze the relationship between Hb variation and cardiovascular death in qualified group or substandard group. Multivariate linear regression analysis was used to analyze the related factors of Hb fluctuation in PD patients.Results:A total of 267 patients were enrolled. There were 160 males (59.93%) in this study. The age was (52.66±13.72) years old, and the median dialysis age was 37(21, 61) months. The patients' baseline Hb (before dialysis) was (80.16±14.89) g/L and at the end of the study Hb was (105.34±22.08) g/L. Body mass index and baseline Hb levels in the high volatility group were lower than those in low volatility group and moderate volatility group (all P<0.05). Both moderate and high volatility groups had lower estimated glomerular filtration rate than that in low volatility group, and high volatility group had higher urea nitrogen level than that in low volatility group (all P<0.05). The amount of erythropoietin usage in the high volatility group was higher than that in moderate volatility group ( P<0.05). The Kaplan-Meier survival analysis results showed that there was no significant difference in survival rate for all-cause death (Log-rank χ2=0.735, P=0.693) and cardiovascular death (Log-rank χ2=2.961, P=0.228) in different Hb volatility groups. Cox regression analysis showed that after adjusting for age, sex, serum creatinine, and blood albumin, higher Hb volatility was associated with a lower risk of cardiovascular death ( HR=0.972, 95% CI 0.947-0.999, P=0.040). After adjusting for related confounding factors, higher Hb volatility was still a protective factor for cardiovascular death in the substandard group ( HR=0.946, 95% CI 0.903-0.992, P=0.022), but there was no significant correlation between Hb fluctuation and all-cause death. Multivariate linear regression analysis results showed that the fluctuation level of Hb was positively correlated with Kt/V ( B=4.682, 95% CI 2.480-6.884, P<0.001) and erythropoietin dosages ( B=0.001, 95% CI 0-0.001, P=0.003), and negatively correlated with baseline Hb ( B=-0.554, 95% CI -0.651--0.457, P<0.001). Conclusions:High Hb variability is a protective factor for cardiovascular death in PD patients with lower Hb level (substandard Hb). Adopting a reasonable program to correct anemia timely to reach the standard level has a greater impact on reducing risk of cardiovascular death in PD patients than Hb variation in anemia treatment.