THE PERITONEAL EQUILIBRATION TEST AT THE START OF PERITONEAL DIALYSIS AND PATIENT OUTCOME. ANALYSIS IN THE PRESENCE OF COMPETING EVENTS

Abstract BACKGROUND AND AIMS The success of peritoneal dialysis (PD) depends on the integrity of the peritoneal membrane. The most common peritoneal functional alteration is an impaired ultrafiltration caused by fast peritoneal solute transfer rate. This situation can be present at start of PD and compromise the durability of the membrane through the stay on PD. If the patient leaves PD for another reason, as in the case of a kidney transplant, it affects the probability of a membrane dysfunction appearance. It is known as a competitive event. The aim of this study was to determine whether baseline peritoneal transport status was a risk factor of mortality and technique failure in a cohort of Spanish PD patients using a statistical competing risk model. METHOD The multicenter retrospective cohort study included adult patients of the Levante Registry PD Work Group in Spain who started PD between February 1993 and June 2020. All patients needed to have a peritoneal equilibration test (PET) performed within the first 6 months after PD start. Patients were followed until technique failure, transplantation, renal function recovery, death, or until September 2020. Peritoneal transport status was considered both as a continuous (D/PCr4h) and as a categorical variable, according to the four groupings of D/PCr values defined by Twardoski. We analysed the effect of peritoneal transport over mortality, peritonitis and technique failure by a competing risk model. Kidney transplantation and renal function recovery were considered competing events. RESULTS A total of 4848 patients were enrolled. Baseline PET measurements were available in 2.307 (47.6%). The median follow-up time was 22.2 months (IQR 11.5–40.5). The main characteristics according to the peritoneal transport status are summarized in Table 1. When peritoneal membrane transport was analysed as a continuous variable, D/PCr was an independent risk factor of technique failure. The hazard ratio subdistribution for technique failure was 1.08 [(1.01; 1.16), P-value = 0.018] for every 0.1 increase in D/P Cr ratio. This effect disappeared when the use of icodextrin was included in the model. Baseline peritoneal transport was not associated with a higher mortality or peritonitis risk. CONCLUSION Basal peritoneal transport rate is an independent risk factor for death-censored technique failure in the Levante DP incident population. The use of icodextrin in these patients seems to mitigate this negative effect and may improve the outcomes in PD in patients with initial fast transport. Conventional methods for survival analysis ignoring the competing events may be inappropriate this cohort of patients.