Continuous ambulatory peritoneal dialysis and automated peritoneal dialysis: are there differences in outcome?

The proportion of peritoneal dialysis (PD) patients on automated peritoneal dialysis (APD) has been steadily increasing over the past decade. In the US, the percentage of PD patients on APD has steadily risen from 9% in 1993 to 54% in 2000. In continuous ambulatory peritoneal dialysis (CAPD), PD exchanges are performed manually, while in APD a mechanical device to assist the delivery and drainage of dialysate is employed. In CAPD, the patient or carer must perform at least 4-5 exchanges everyday. Many problems inherent to CAPD such as lack of sustained patient motivation over long periods of time, technique failure and recurrent peritonitis, led to a resurgence of interest in APD. APD has been reported to have several advantages over CAPD including lower incidence of peritonitis, better small solute clearances and reduced incidences of hernias. APD, especially in the form of nocturnal intermittent peritoneal dialysis (NIPD), has also been suggested to offer a number of psychosocial and physical benefits over CAPD mainly on account of fewer connections and being free of fluid in the abdomen during daytime. Such benefits relate to better dialysis acceptability for workers, school students or carers of elderly patients, pain and body image difficulties and reduced intra-abdominal pressures. APD is also considered to be more suitable form of PD in patients who have a rapid rate of solute transfer across their peritoneal membrane (high transporters) because of the ability to perform rapid frequent exchanges with shorter dwell times. It is not still clear if, with APD when compared to CAPD, a more rapid decline in residual renal function is present. Since the direct costs of APD are over 20% greater than CAPD and given this increasing trend towards greater use of APD, the aim of this paper is to understand if there are really differences in terms of quality of life and outcomes in favor of APD when compared to CAPD.