Division of Nephrology and Dialysis Hospital of Martina Franca Italy
Sir,
We read with interest the paper by Huang et al. [1]. Their results show that the incidence of peritonitis in patients using automated peritoneal dialysis (APD) is significantly lower than that of patients using CAPD based on Y-disconnect systems [1]. These results allow them to conclude that, since reducing the peritonitis rate helps to maintain technical survival during peritoneal dialysis (PD), from this viewpoint, APD may be preferred for patients undergoing PD.
This paper prompted us to conduct an observational study in order to compare CAPD with APD in terms of peritonitis incidence in our PD programme in which CAPD is the first and, in the majority of cases, the only PD therapy. APD may be adopted only afterwards, exclusively for two clinical reasons, namely reduction or loss of ultrafiltration rate and/or reduction of dialysis efficiency, i.e. weekly Kt/Vurea<2.0. Peritonitis was defined according to the criteria also adopted by Huang et al. [1]. The same staff, blind perimedial catheter implantation, postoperative management, medical care and training have been applied since the start of our PD programme in January 1993. The present observational study started in January 1996 in order to avoid the potential bias of a lesser quality in the first 3 years of our PD programme. The results are shown in Tables 1 and 2
. They are completely different from those given by Huang et al. and lead us to conclusions opposite to theirs [1]. In our centre, peritonitis episodes were actually more frequently observed with APD than with CAPD. This was true for comparisons between all CAPD-treated and APD-treated patients (Table 1
) and also for the smaller subgroup of patients who had been transferred from CAPD to APD treatment (Table 2
). Actually, reported comparisons of peritonitis incidence in CAPD and APD are contradictory and difficult to interpret for several reasons. One of these is that peritonitis incidence is extremely variable in different studies, indicating marked differences in patient selection criteria and dialysis procedures [15]. Differences in other risk factors for peritonitis are a second likely explanation for these discrepancies [15]. Thus, prospective randomized studies are mandatory to overcome these limitations. However, to the best of our knowledge only two prospective randomized studies have been designed to test the hypothesis of a potential difference between the effects of APD and CAPD on clinical outcomes; the first one was able to show a lower peritonitis rate for APD-treated patients [6]; the second one was unable to demonstrate such results, probably due to a small patient sample size [7].
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