In this retrospective observational cohort study, we compared the impact of the initial dialysis modality on the survival of patients with ESRD beginning dialysis in our center between January 1, 2010, and December 31, 2018. Our study showed that mortality was significantly higher in patients initiating dialysis with HD than those initiating dialysis with PD in the whole cohort, but in the propensity score-matched cohort, there was no difference between HD and PD patients. We also found that PD was more favorable with respect to survival than HD in patients with diabetes.
Randomized controlled trials assessing the independent effect of HD and PD on survival have been impossible to conduct [3]. Several studies reported that there is no difference in survival between the modalities [4–7], which is consistent with our findings. Several studies also reported favorable outcomes of PD in younger patients or during the first 1–2 years of dialysis treatment compared to the outcomes of HD [12, 15, 16]. We did not find any interaction between age and dialysis modality related to outcomes, and the concern about increased mortality in PD patients if treatment is continued beyond 1–2 years was also not supported by our study.
In another subgroup analysis of our matched cohort, significantly better survival was shown in patients with diabetes whose treatment was initiated with PD versus those initiating with HD. This is contradictory to the results of several studies, which have claimed that patients with diabetes mellitus did worse on PD than on HD [17, 18], while favorable outcomes of PD were reported in patients without diabetes [10, 19]. It was generally recognized in previous studies that PD therapy may affect blood glucose control in ESRD patients because the dialysate used for PD contains glucose [20–22], and diabetic patients are prone to developing disorders of lipid metabolism [23], which might accelerate the process of arteriosclerosis and increase the incidence of cardiovascular events [24, 25]. There were also some studies that found no interactions between diabetes mellitus and initial modality concerning mortality [9, 10, 26].
There are several reasons why our results may diverge from those of previous studies comparing outcomes in PD and HD in patients with diabetes. First, therapy skills, including elective dialysate and automated peritoneal dialysis (APD) prescription while avoiding glucose load, might have been responsible for our favorable results. Second, the team responsible for training, management and follow-up of PD patients was of high quality in our single center, which might account for the different results of this single center study compared to other studies. Moreover, when PD fails, it is common to switch to HD; therefore, the mortality rate of these patients was lower than that of HD patients. There were also reports consistent with our discovery that PD showed better outcomes in diabetes patients [27, 28].
With regard to the risk factors associated with survival, we found that age, sex, and cerebrovascular disease were risk factors, which are not totally consistent with those reported by other studies. Some studies [6, 29–31] discovered that age and diabetes were risk factors associated with death. Another study in eastern China [10] followed up 22,379 patients for a median of 29 months and found that age, diabetic nephropathy, and cardiovascular disease were risk factors.
There are several limitations of this study worth mentioning. The main limitation is that it was not a randomized study but rather a retrospective observational cohort study, and propensity score matching can account only for observed confounders. Despite propensity score matching and adjustment for several confounding factors, residual confounding cannot be excluded. Therefore, this study may not be completely free of bias due to confounding. Second, only baseline laboratory test results were recorded, which might be altered during dialysis treatment. Therefore, the laboratory tests shown in this study could not reflect the situation of patients in the treatment process. Third, the study population was small (250 patients), and the survival rates of only the first 3 years were compared.