Effects of pretransplant peritoneal vs hemodialysis modality on outcome of first kidney transplantation from donors after cardiac death

This was a prospective cohort study of ESRD (defined as eGFR< 15 ml/min/1.73 m²) patients who received their first kidney transplantation from DCD between January 2014 and December 2016 in renji hospital affiliated to School of Medicine of Shanghai Jiaotong University, a hospital at Pudong New District, Shanghai, China. During the transplantation, the technical issues that may affect the outcome of transplant like organ transplantation, preservation as well as surgical operation were all performed by same transplant team in our hospital. DCD was defined as awaiting cardiac arrest after withdrawal of life-supporting treatment in the intensive care unit.

Patients above 18 years of age who had been on the same dialysis modality (hemodialysis or peritoneal dialysis) for at least 3 months without a switch or underwent transplantation before the initiation of dialysis (pre-emptive kidney transplantation, PKT) were included. Patients who were living donor transplant, second KT or multiple organ transplants and lost to follow-up were excluded. Follow-up was terminated on August 2017. Finally data on 104 HD and 98 PD group met the inclusion criteria and were included for comparative outcome analysis. 5 PKT patients were analyzed as the control group (Fig. 1).

The protocol of this study was reviewed and approved by the Ethics Committee of Renji hospital, and patients were included only after signing informed consent.

Donor variables included age, gender, BMI, blood group, percentage of hypertension, mean time of intensive care unit(ICU) stay, HLA mismatching, estimated glomerular filtration rate (eGFR) and the causes of death. The baseline variables of recipients in two groups of patients on hemodialysis or peritoneal dialysis included age, gender, body mass index (BMI), blood group, duration time on pretransplant dialysis, post-transplant hospital stay and follow-up time, preoperative medical condition, percentage of anti-hypertensive drugs required, percentage of hepatitis B virus (HBV) infection, native kidney diseases, pretransplant urinary volume, percentage of anuric patients and immunosuppresion therapy. The laboratory parameters of white blood cell count, creatinine, cholesterol, triglyceride of both donors and recipients were collected. The percentage of neutrophilic granulocyte and lymphocyte, haemoglobin, serum urea nitrogen, serum uric acid, serum albumin, alanine aminotransferase (ALT), blood glucose, serum potassium, serum sodium, parathyroid hormone, serum calcium, serum phosphate, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and lymphocyte subtypes were also obtained from recipients. Among which the eGFR was estimated using the chronic kidney disease epidemiology collaboration (CKD-EPI) equation which was calculated according to the gender, the serum creatinine, the age and the race.

Post-transplant variables included renal function (serum creatinine, 24 h urine volume and the eGFR), haemoglobin, serum albumin, cholesterol, triglyceride, serum calcium and serum phosphate. The postoperative complications during hospitalization of delayed graft function (DGF), acute rejection (AR) and surgical complications including the urinaryfistula, hydronephrosis and hematoma after tranplantation were recorded. The infective complications including viral infection(cytomegalovirus, JC virus, BK virus, varicella zoster virus), fungal infection as well as bacterial infection(tuberculosis, urinary tract infection, acute bacterial pneumonia, gastrointestinal infection) were recorded during hospitalization and the whole follow-up time. The DGF was defined as the requirement for dialysis in the first week after transplantation, or serum creatinine level increased, remained unchanged, or decreased by less than 10% per day immediately after surgery [14, 15]. All patients with biopsy-proven acute rejection and those with features of antibody-mediated rejection, with borderline changes and allograft dysfunction who received treatment for acute rejection were considered to have rejection [14, 15]. The patient, graft and death-censored graft survival were compared between HD and PD groups. The causes of patient mortality and graft failure were recorded. Death-censored graft failure was defined as suffering graft failure without death.

The statistical analysis was performed by using the SPSS 22 version software. All numeric variables were tested for normality of their distribution. Independent samples t-test and Mann-Whitney U test were respectively used for analyzing data whose distribution are normal and abnormal. Results are described as mean ± standard deviations (SD) for normally distributed data, median and interquartile range (IQR, pp. 25–75) for abnormally distributed data. The Chi square or Fisher’s exact tests was utilized to compare the categorical variables between the two groups. The results were expressed in numbers and relative frequencies [n(%)].

The baseline information of recipients and donors in HD, PD and PKT group was analyzed. Among them, PKT group was analyzed as the control group. Patients in both PD and HD groups were comparable for demographic and clinical characteristics (Table 1). The pretransplant laboratory parameters in PD group were lower compared with HD group with regard to haemoglobin, serum albumin, serum potassium and serum calcium (p < 0.05). On the contrary, the serum creatinine, serum urea nitrogen and serum uric acid were higher in PD group (p < 0.05) (Table 2). Donors characteristics was comparable for recipient in both PD and HD groups (Table 3).

The post-transplant renal function outcomes of PKT were labeled as control. In view of the HD and PD group, the post-transplant serum creatinine showed no differences throughout the follow-up between the HD and PD groups (p > 0.05) (Fig. 2). Pretransplant serum creatinine was higher in PD patients (p < 0.05). There was no differences (p = 0.210) in serum creatinine reduction to half of baseline in two groups, with 1.0 (1.0, 2.0) d in HD and 1.0 (1.0, 1.3) d in PD group. The serum creatinine levels at different post-transplant time points reduced statistically compared to pretransplant, which were coherent between the HD and PD groups (p < 0.001). There were significant differences in serum creatinine at different time points throughout the follow-up within two groups (p < 0.001). The 24-h urinary volume remained similar between the two groups during the follow-up period (p > 0.05) (Fig. 3). The mean eGFR at 1 month (68.52 ± 23.72 vs 68.04 ± 28.66, p = 0.902), 6 month (68.45 ± 23.15 vs 74.85 ± 22.87, p = 0.167) and last follow-up (69.74 ± 24.65 vs 68.54 ± 26.01, p = 0.737) were also similar between the two groups (Table 4).

Triglyceride levels at 6 months post transplantation were significantly higher in the PD group [PD: 2.1(1.8,2.5) vs HD:1.6 (1.2,2.1), p = 0.010]. At other time points the triglyceride levels were similar in two groups. There were no statistical differences between PD and HD patients in haemoglobin, serum albumin, cholesterol, triglyceride, serum calcium and serum phosphate levels throughout the follow-up period (Table 4).

There were only 2 infective complications in PKT group. For HD and PD group, the hyperacute rejection didn’t appear in both groups. The acute rejection rate in HD group [6.7% (7/104)] were similar to PD group [6.1% (6/98)] (p = 0.860). There were total 35 patients (17.3%) with DGF, 19 patients (18.3%) in HD and 16 (16.3%) in PD group. Statistically no significant differences (p = 0.715). Surgical and infective complications throughout the hospitalization and follow-up period were did not differ between two groups (Table 5).

There were no death and graft failure in PKT group. There were total 7 deaths, 4 in the HD and 3 in the PD group. The patient survival rate between two groups showed no significant differences (p = 1.000). There were 13 graft failure, 7 in HD and 6 in PD group, and causes of graft failure were statistically different between two groups (p < 0.001). The graft survival rates were similar between the two groups (p = 0.860). The death-censored graft failure i.e. graft failure without death (3 in each of HD and PD group) was not different between the two groups (p = 1.000) (Table 6).

The cox proportional hazards model showed pretransplant dialysis modality (HD and PD) had no correlation with patient survival or graft failure or death-censored graft survival After adjusting for other related multiple risk factors, the PD patients had similar rates of graft failure compared with HD in multivariate cox proportional hazards analysis (Table 7). When separately analyzed for HD and PD groups, the surgical complications in HD patients were independent stimulating factors of graft failure and DGF was an independent factor inversely correlated with graft survival in PD patients (Table 8).