Background: Several risk factors for patients treated with peritoneal dialysis (PD) have now been identified. These include age, comorbid disease, nutritional status, loss of residual renal function (RRF) and high peritoneal solute transport. This is not the same, however, as knowing what actually happens to these patients, particularly in the long-term. The purpose of this review was to give as complete a description as is currently possible of the long-term PD patient.
Methods: The literature was surveyed for publications that provide longitudinal cohort data of either selected or unselected patient groups. Detailed data from the Stoke PD Study is presented in the context of these studies. Three principle aspects of what really happens to patients were considered: (1) death, both cause and mode of death; (2) technique failure, with reference to peritoneal function and how the cause of technique failure related to patient survival; and (3) evolution of clinically relevant parameters of patients on PD, such as nutrition and peritoneal function.
Results: Sudden death and debilitation were the predominant modes of death, with sepsis playing a contributory role. Debilitation was important regardless of co-existent comorbid disease, and time to death was not influenced by the mode of death. Predominant causes for technique failure remain peritonitis and ultrafiltration, the latter becoming more important with time on treatment. Technical failure is associated with poorer survival, particularly when due to multiple peritonitis or failure to cope with treatment. Cox regression demonstrated that whereas low albumin, loss of RRF and high solute transport predicted patient death, only high solute transport predicted technique failure. Longitudinal changes over the first five years of treatment included loss of RRF, increasing solute transport and following an initial improvement in nutritional state, a decline after two years. Patients surviving long-term PD (at least five years, N = 25) were characterized by prolonged RRF, maintained nutrition and lower solute transport in the medium term.
Conclusions: Several studies of long-term PD in the literature now complement each other in providing a picture of what really happens to PD patients. The links between loss of solute clearance and poor peritoneal ultrafiltration combining to exacerbate sudden or debilitated death and technique failure are emerging. For PD to be successful as a long-term therapy, strategies that maintain nutrition and preserve peritoneal membrane function must be developed.