Do the Y-set and double-bag systems reduce the incidence of CAPD peritonitis?

A systematic review of randomized controlled trials

Conal D. Daly1,, Marion K. Campbell2, Alison M. MacLeod1, D. June Cody1,2, Luke D. Vale2,3, Adrian M. Grant2, Cam Donaldson3,5, Sheila A. Wallace2, Paul D. Lawrence4 and Izhar H. Khan1

1 Department of Medicine and Therapeutics, 2 Health Services Research Unit, 3 Health Economics Research Unit, 4 Medical School Library, University of Aberdeen, Aberdeen, UK 5 Current address: Departments of Economics and Community Health Sciences, University of Calgary, Canada



   Abstract
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 
Background. Peritonitis is the most frequent serious complication of continuous ambulatory peritoneal dialysis (CAPD). It has a major influence on the number of patients switching from CAPD to haemodialysis and has probably restricted the wider acceptance and uptake of CAPD as an alternative mode of dialysis. This systematic review sought to determine if modifications of the transfer set (Y-set or double-bag systems) used in CAPD exchanges are associated with a reduction in peritonitis and an improvement in other relevant outcomes.

Methods. Based on a comprehensive search strategy, we undertook a systematic review of randomized or quasi-randomized controlled trials comparing double-bag and/or Y-set CAPD exchange systems with standard systems, or comparing double-bag with Y-set systems, in patients with end-stage renal disease (ESRD) treated with CAPD. Only published data were used. Data were abstracted by a single investigator onto a standard form and subsequently entered into Review Manager 4.0.4. Its statistical package, Metaview 3.1, calculated an odds ratio (OR) for dichotomous data and a (weighted) mean difference for continuous data with 95% confidence intervals.

Results. Twelve eligible trials with a total of 991 randomized patients were identified. In trials comparing either the Y-set or double-bag systems with the standard systems, significantly fewer patients (133/363 vs 158/263; OR 0.33, 95% CI 0.24–0.46) experienced peritonitis and the number of patient-months on CAPD per episode of peritonitis was consistently greater. When the double-bag systems were compared with the Y-set systems significantly fewer patients experienced peritonitis (44/154 vs 66/138; OR 0.44, 95% CI 0.27–0.71) and the number of patient-months on CAPD per episode of peritonitis was also greater.

Conclusions. Double-bag systems should be the preferred exchange systems in CAPD.

Keywords: CAPD; double bag; peritonitis; randomized controlled trials; systematic review; Y-set



   Introduction
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 
Continuous ambulatory peritoneal dialysis (CAPD) has been an alternative to haemodialysis for patients with end-stage renal disease (ESRD) since 1976 [1]. It may be the first-choice dialysis therapy and in a number of countries, including the United Kingdom, a significant proportion of the ESRD population are treated by this modality in preference to chronic haemodialysis [2]. Peritonitis is the most common serious complication of peritoneal dialysis and is the leading cause of technique failure requiring a switch to haemodialysis [3]. Undertaking a peritoneal dialysis exchange is one of the key points during CAPD when micro-organisms can be inadvertently transferred via the lumen of the peritoneal catheter into the peritoneal space (intraluminal route), causing peritonitis. The CAPD transfer system used may therefore have an important bearing on both the incidence of peritonitis and CAPD technique failure.

There are three main types of catheter connecting systems. In the standard or straight connecting system the catheter is connected to the dialysate solution bag using a straight piece of tubing and a ‘spike’ or a luer lock device. At each exchange a new connection is made and the bag is drained. The empty bag is rolled up and remains attached until the next exchange when the process is repeated. The second type of transfer system is the Y-set in which the patient disconnects from the bags between exchanges (disconnect system). When a new exchange is due a Y-connection with one limb connected to an empty bag and one to a bag containing fresh dialysate is used [46]. During an exchange the peritoneal dialysate is first drained from the peritoneal cavity into the empty bag. Before introducing the fresh dialysis solution into the peritoneal cavity the Y-connecting system is first flushed with fresh dialysis solution and drained into the drainage bag. This allows any bacteria to be flushed into the spent fluid. The fresh fluid is then introduced into the peritoneal cavity and the Y-connector is disconnected from the CAPD catheter. The early Y-set technique, in addition, flushed the system with a disinfectant, a hypochlorite, during each exchange [7]. The third system, the double-bag (twin-bag) system, was a further development of the Y-set disconnect systems. With this system the connection with the fresh dialysis solution bag is already made and the patient has to perform one less connection procedure [810]. It has been suggested that use of the Y-set transfer or double-bag systems will lead to a reduced frequency of CAPD peritonitis [7] and some [11,12] but not all [13] observational studies have indicated an association between use of the standard connect system and a significantly increased risk of peritonitis. At present a considerable proportion of CAPD patients, including those in the UK, continue to use the standard system [14,15]. Other techniques such as the ultraviolet germicidal system [16,17], in-line bacteriological filters [17,18], and heat sterilization [17,19] have been developed and used in an attempt to reduce peritonitis rates; they were not considered as part of this review.

We undertook a systematic review of rigorous trials to determine if Y-set (and modifications) and double-bag systems are associated with an improvement in CAPD peritonitis and other relevant outcomes.



   Subjects and methods
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 
Identification of trials
We attempted to identify all eligible trials which compared (i) double-bag (experimental group) and/or Y-set (experimental group) with standard CAPD exchange systems (control group), and (ii) double-bag (experimental group) with Y-set (control group) in patients with ESRD maintained on CAPD. To be eligible, allocation to treatment groups had to be randomized (e.g. sealed envelopes with third-party involvement) or quasi-randomized (e.g. alternate patients or alternate treatments). We included studies where disinfectant had been used to flush and/or to be retained in the elements of the Y-set system. For either the Y-set or double-bag systems the sequence of the exchanges could vary: (i) drain/flush/fill or (ii) flush/drain/fill.

Because this was one of a number of reviews we undertook relevant to the management of ESRD, a broad search strategy was employed which attempted to identify all randomized controlled trials (RCTs) or quasi-RCTs relevant to the management of ESRD. This strategy is detailed in Campbell et al. [20]. Updated electronic searches of Medline, Embase, and the Cochrane Library specific to this review were undertaken in November 1999.

Hard copies of each relevant identified study were assessed independently by two assessors for subject relevance and methodological quality, using a standard form. Details concerning method of random allocation, blinding, description of withdrawals and dropouts, and whether data were analysed on an intention to treat basis were noted.

Data abstraction
Data on predetermined outcome measures were abstracted from included studies using a standard form, by a single assessor and were entered onto Review Manager 4.0.4 software. All data were independently checked from the original papers by a second person. Only published data were used; no raw data were sought. The outcome measures were: (i) number of patients experiencing peritonitis and its frequency (primary outcome), (ii) number of patients experiencing exit-site infections and their frequency, (iii) number of patients in whom CAPD catheters were removed, (iv) number of patients switching to haemodialysis, (v) number of patients hospitalized and average number of days of hospitalization, (vi) measures of quality of life and patient preference, (vii) mortality.

Data analysis
Quantitative data were analysed, where appropriate, using the meta-analysis package of Review Manager 4.0.4, Metaview 3.1, to calculate a Peto's odds ratio for dichotomous variables and a weighted mean difference for continuous variables, with 95% confidence intervals. The methods are discussed in detail in Campbell et al. [20].



   Results
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 
We identified twelve RCTs comparing double-bag, Y-set, and standard transfer systems with a total of 991 randomized patients (Table 1Go). One study [32] compared all three system types, seven compared only Y-set with standard systems [2130], one compared only double-bag with standard systems [31] and three compared only double-bag with Y-set systems [3335]. Some of the trials' reports did not include data relevant to all this review's outcomes or reported these data in a manner that precluded inclusion in the meta-analyses (e.g. standard deviations or exact P-values were omitted). As a consequence, some of the meta-analyses include fewer studies and fewer patients than might be expected. The publication of the studies were fairly evenly spread over a 16-year period from 1983 (Maiorca et al. [21,22]) to 1999 (Li et al. [35]). Details of the methodological quality of the included RCTs are outlined in Table 1Go. The method of randomization should ensure that treatment allocation remains unknown until a patient is irrevocably recruited to a study. Only four studies described the method of randomisation. One [32] described a probably secure method of random allocation (central list of random numbers with order of allocation sent to participating centres in sealed envelopes). Two did not completely describe their method of random allocation: Churchill [26,27] (used ‘a variable blocking factor, by the coordinating centre’ no other details given), Maiorca et al. [21,22] (‘closed envelope system’, no other details given). Cheng et al. [29] described an insecure method of random allocation (random number tables but ‘investigators were not blind to treatment previously recruited patients received’ and next treatment could be anticipated). All 12 had parallel designs. Only two [25,29] failed to describe withdrawals and dropouts. None of the study reports clearly stated that data were analysed on an intention-to-treat basis, although for only four [21,22,32,34,35] was it clear that analysis was not on an intention-to-treat basis. Blinding or masking was infrequently described and none of the studies stated specifically that patients, healthcare providers, or outcome assessors were masked/blinded.


View this table:
[in this window]
[in a new window]
 
Table 1. Description of included studies

 



   Peritonitis
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 
Significantly fewer patients (133/363 vs 158/263) experienced peritonitis when using either the Y-set or double-bag systems compared with the standard systems (OR 0.33, 95% CI 0.24–0.46) (Figure 1Go). Analyses limited to trials comparing double-bag systems with standard and then Y-set systems vs standard were consistent with this, significantly favouring the newer methods. When the two newer methods were compared, significantly fewer patients using the double-bag system experienced peritonitis (44/154 vs 66/138; OR 0.44, 95% CI 0.27–0.71) (Figure 1Go). Data describing the number of patient-months on CAPD per episode of peritonitis were consistent with this (Table 2Go). All trials comparing either Y-set or double-bag to standard systems favoured the newer systems, and all trials comparing double-bag with Y-set systems [3235] consistently reported greater numbers of months per episode of peritonitis with the double-bag systems.



View larger version (42K):
[in this window]
[in a new window]
 
Fig. 1. Number of patients suffering peritonitis comparing double bag, Y-set and standard transfer systems in CAPD: meta-analyses of RCTs.

 

View this table:
[in this window]
[in a new window]
 
Table 2. Number of patient-months on CAPD per episode of peritonitis reported in individual RCTs

 



   Exit-site infections
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 
Three studies reported the number of patients who experienced exit-site infections [26,27,28,31] (Figure 2Go). The meta-analyses found no significant differences when both the Y-set and double-bag systems were compared with the standard systems (overall, 39/131 vs 40/133; OR 0.99, 95% CI 0.57–1.72). None of the studies comparing the double-bag with the Y-set systems reported the number of patients experiencing exit-site infections. Apart from Kiernan [33], who favoured the double-bag system, none of the four RCTs reporting the number of months per episode of exit-site infection showed any difference (Table 3Go).



View larger version (37K):
[in this window]
[in a new window]
 
Fig. 2. Number of patients suffering exit-site infections comparing double bag, Y-set and standard transfer systems in CAPD: a meta-analyses of RCTs.

 

View this table:
[in this window]
[in a new window]
 
Table 3. Number of patient-months on CAPD per episode of exit-site infection reported in individual RCTs

 



   Additional secondary outcomes
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 
There was no convincing evidence from meta-analyses of any consistent differences between the systems in relation to technique failure, need for CAPD catheter removal, hospitalization, quality of life, or reported mortality (data not shown).



   Discussion
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 
This review generated clear evidence of benefit in terms of a reduction in the number of patients experiencing peritonitis when Y-set or double-bag systems were compared with standard systems (OR 0.33, 95% CI 0.24–0.46). Although the numbers were smaller and the confidence intervals wider, there was also additional benefit from the use of the double-bag systems in comparison with the Y-set systems (OR 0.44, 95% CI 0.27–0.71). The included RCTs also consistently reported greater numbers of patient-months on CAPD per episode of peritonitis when comparing either Y-set or double-bag with standard systems, and additional benefit from the double-bag systems when compared with the Y-set systems (Table 2Go). No benefit was demonstrated in terms of a reduction in exit-site infections with either the Y-set or double-bag systems. The proposed mechanisms for peritonitis reduction with Y-set and double-bag systems (decrease in intraluminal bacterial contamination because of decreased number of connections/disconnections and flush before fill procedure) would be consistent with this failure to reduce exit-site infections.

This review considered the data from all RCTs that have compared Y-set, double-bag and standard systems. It was difficult to assess the quality of the 12 RCTs identified. The descriptions of the method of random allocation, of whether data were analysed on an intention-to-treat basis and of whether patients, healthcare providers, and outcome assessors were masked were often incomplete (Table 1Go). A clear description of trial methodology, such as through wider use of the CONSORT statement guidelines [36], would greatly assist validity assessment and exploration of heterogeneity between studies.

The review was facilitated by the primary outcome, peritonitis, being consistently reported and similarly defined throughout all the included studies. In contrast, relatively few of the included RCTs reported data relevant to other outcomes. The review was unable to determine clearly if the Y-set and double-bag systems were beneficial or harmful in terms of the number of CAPD catheters removed, technique failure, or hospitalization. Similarly, while the available quality of life data appear to support the use of double-bag in preference to Y-set systems [27,28] the data are limited. This review found no differences in mortality when the three systems were compared.

The interventions within each group were not identical. For example, in the early Y-set studies, sodium hypochlorite disinfectant was left in components of the Y-system between exchanges [47]. It was initially assumed that the use of disinfectant contributed significantly to the reduction in peritonitis rates. However, subsequent trials showed equal benefit using the Y-modification without disinfectant and the use of disinfectant was later associated with chemical peritonitis and the development of sclerosing peritonitis, and hence the practice was discontinued. Assessing a number of different modifications in a single standard RCT risks failing to identify which change(s) contributed to any beneficial or adverse effects.

Peritonitis was the primary outcome of this review. There is clear evidence that use of either the Y-set or the double-bag systems compared with the standard systems is associated with a statistically and clinically significant reduction of peritonitis. There is also evidence that the double-bag system is superior to the Y-set system in this respect.



   Implications for practice
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 
From the purely clinical perspective, the standard systems (spike or luer lock) should no longer be used because of the clearly increased risk of peritonitis. The additional benefit the double-bag has over the Y-set systems suggests that where resources permit, the double-bag CAPD exchange systems should be used routinely in clinical practice. Policy-makers need to decide whether the necessary resources can be made available to allow this routine adoption of the double-bag system.



   Implications for research
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 
Peritonitis is the most frequent serious complication of CAPD. It is essential that innovations in CAPD technique or technology designed to reduce peritonitis rates are subject to rigorous assessment by well-designed RCTs. The double-bag system should be the standard against which future design modifications in CAPD transfer technology are compared. It should also be the routine best practice treatment when trials concerning any aspect of CAPD are being undertaken. If more than one intervention is being considered, clinical trials should be designed to identify clearly to which intervention any beneficial or adverse effects can be attributed. There is likely to be no additional research benefit in further trials comparing double-bag, Y-set, and standard CAPD exchange systems. A health economic evaluation of the use of double-bag or Y-set compared with standard systems needs to be undertaken. This should allow health care purchasers to decide if the additional benefits of double-bag and Y-set systems are worth any potential extra cost.



   Acknowledgments
 
This work was funded by a grant from the NHS Executive Research and Development Health Technology Assessment Programme. The Health Services Research Unit and the Health Economics Research Unit are funded by the Chief Scientist's Office, Scottish Executive Health Department. The authors would like to thank Carol Ritchie and Gloria Montague for secretarial support.



   Notes
 
Correspondence and offprint requests to: Conal Daly, Department of Medicine and Therapeutics, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK. Back



   References
 Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Peritonitis
 Exit-site infections
 Additional secondary outcomes
 Discussion
 Implications for practice
 Implications for research
 References
 

  1. Popovich RP, Moncrief JW, Decherd JF, Bonar JB, Pyle WK. The definition of a novel portable/wearable equilibrium peritoneal dialysis technique (abstract). ASAIO Trans1976; 5: 64
  2. Valderrabano F, Berthoux FC, Jones EHP, Mehls O (on behalf of the ERA-EDTA Registry). Report on management of renal failure in Europe, XXV, 1994. End stage renal disease and dialysis report. Nephrol Dial Transplant1996; 11 [Suppl 1]: 2–21[ISI][Medline]
  3. Canada-USA (CANUSA) Peritoneal Dialysis Study Group. Adequacy of dialysis and nutrition in continuous peritoneal dialysis: association with clinical outcomes. J Am Soc Nephrol1995; 7: 198–207[Abstract]
  4. Buoncristiani U, Bianchi P, Cozzari M, Carobi C, Quintaliani G, Barbarossa D. A new safe simple connection system for CAPD. Nephrol Urol Androl1980; 1: 45–50
  5. Buoncristiani U. Continuous ambulatory peritoneal dialysis connection systems. Perit Dial Int1993; 13 [Suppl 2]: S139–145[Medline]
  6. Buoncristiani U. Birth and evolution of the ‘Y’ set. ASAOI J1996; 42: 8–11
  7. Buoncristiani U, Cozzari M, Quintaliani G, Carobi C. Abatement of exogenous peritonitis risk using the Perguia CAPD system. Dial Transplant1983; 12: 14–25[ISI]
  8. Bazzato G, Landini S, Coli U, Lucatello S, Fracasso A, Moracchiello M. A new technique of continuous ambulatory peritoneal dialysis (CAPD): double-bag system for freedom to the patient and significant reduction of peritonitis. Clin Nephrol1980; 13: 251–254[ISI][Medline]
  9. Lewis J, Abbott J, Crompton K, Fowler I, Smith B. CAPD disconnect systems: UK peritonitis experience. Adv Perit Dial1992; 8: 306–312[Medline]
  10. Balteau P, Peluso FP, Coles G et al. Design and testing of the Baxter Integrated Disconnect System (IDS). Perit Dial Int1991; 11: 131–136[ISI][Medline]
  11. Golper TA, Brier ME, Bunke M et al. Risk factors for peritonitis in long-term peritoneal dialysis: the Network 9 peritonitis and catheter survival studies. Am J Kidney Dis1996; 28: 428–436[ISI][Medline]
  12. Port FK, Held PJ, Nolph KD, Turenne MN, Wolfe RA. Risk of peritonitis and technique failure by CAPD connection technique: a national study. Kidney Int1992; 42: 967–974[ISI][Medline]
  13. Bailie GR, Rasmussen R, Hollister A, Eisele G. Incidence of CAPD peritonitis in patients using UVXD or O-set systems. Clin Nephrol1990; 33: 252–254[ISI][Medline]
  14. UKRENALREG 1998, UK Renal Registry, Bristol, UK
  15. Cheng IK. Peritoneal dialysis in Asia. Perit Dial Int1996; 16 [Suppl 1]: S381–385[Medline]
  16. Nolph KD, Prowant B, Serkes KD et al. A randomized multicenter clinical trial to evaluate the effects of an ultraviolet germicidal system on peritonitis rate in continuous ambulatory peritoneal dialysis. Perit Dial Bull1985; 5: 19–24[ISI]
  17. Churchill DN. CAPD peritonitis: a critical appraisal of prophylactic strategies. Semin Dial1991; 4: 94–100[ISI]
  18. Slingeneyer A, Mion C. Peritonitis prevention in continuous ambulatory peritoneal dialysis; long term efficacy of a bacteriological filter. Proc Eur Dial Transplant Assoc1982; 19: 388–395[ISI]
  19. Durand PY, Chanliau J, Gamberoni J, Kessler M. La connectologie pour le traitement par dialyse peritoneale de l'insuffisance renale chronique. Nephrologie1995; 16: 37–44[ISI][Medline]
  20. Campbell MK, Daly C, Wallace SA et al. Evidence-based medicine in nephrology: identifying and critically appraising the literature. Nephrol Dial Transplant2000; 15: 000–000
  21. Maiorca R, Cantaluppi A, Cancarini GC et al. Prospective controlled trial of a Y-connector and disinfectant to prevent peritonitis in continuous ambulatory peritoneal dialysis. Lancet1983; 2: 642–644[Medline]
  22. Maiorca R, Cantaluppi A, Cancarini GC et al. ‘Y’ connector system for prevention of peritonitis in CAPD: a controlled study. Proc Eur Dial Transplant Assoc1983; 20: 223–229[ISI][Medline]
  23. Rottembourg J, Brouard R, Issad I, Allouache M, Jacobs C. Prospective randomised study about Y connectors in CAPD patients. Adv Perit Dial1987; 107–113
  24. Rottembourg J, Brouard R, Issad I et al. Prevention des peritonites au cours de la dialyse peritoneale continue ambulatoire. Interet des systemes deconnectables. Presse Med1988; 17: 1349–1353[ISI][Medline]
  25. Lindholm T, Simonsen O, Krutzen L et al. Evaluation of a new take-off system: a prospective randomized multicenter study. Adv Perit Dial1988; 4: 264–265
  26. Churchill DN (for Canadian CAPD Clinical Trials Group). Randomised clinical trial comparing peritonitis rates among new CAPD patients using the Y set disinfectant system to standard systems. (Abstract) Kidney Int1989; 35: 268
  27. Churchill DN, Taylor DW, Vas SI et al. (for Canadian CAPD Clinical Trials Group). Peritonitis in continuous ambulatory peritoneal dialysis (CAPD): a multi-centre randomized clinical trial comparing the Y connector disinfectant system to standard systems. Perit Dial Int1989; 9: 159–163[ISI][Medline]
  28. Owen JE, Walker RG, Lemon J, Brett L, Mitrou D, Becker G. Randomized study of peritonitis with conventional versus O-set techniques in continuous ambulatory peritoneal dialysis. Perit Dial Int1992; 12: 216–220[ISI][Medline]
  29. Cheng IK, Chan CY, Cheng SW et al. A randomized prospective study of the cost-effectiveness of the conventional spike, O-set, and UVXD techniques in continuous ambulatory peritoneal dialysis. Perit Dial Int1994; 14 (3): 255–260[ISI][Medline]
  30. Li PKT, Chan TH, So WY, Wang AYM, Leung CB, Lai KN. Comparison of Y-set disconnect system (Ultraset) versus conventional spike system in uremic patients on CAPD: outcome and cost analysis. Perit Dial Int1996; 16 [Suppl 1]: S368–370[Medline]
  31. Dryden MS, McCann M, Wing AJ, Phillips I. Controlled trial of a Y-set dialysis delivery system to prevent peritonitis in patients receiving continuous ambulatory peritoneal dialysis. J Hosp Infect1992; 20: 185–192[ISI][Medline]
  32. Monteon F, Correa-Rotter R, Paniagua R et al. Prevention of peritonitis with disconnect systems in CAPD: A randomized controlled trial. Kidney Int1998; 54: 2123–2128[ISI][Medline]
  33. Kiernan L, Kliger A, Gorban-Brennan N et al. Comparison of continuous ambulatory peritoneal dialysis-related infections with different ‘Y-tubing’ exchange systems. J Am Soc Nephrol1995; 5: 1835–1838[Abstract]
  34. Harris DCH, Yuill EJ, Byth K, Chapman JR, Hunt C. Twin-versus single-bag disconnect systems: infection rates and cost of continuous ambulatory peritoneal dialysis. J Am Soc Nephrol1996; 7: 2392–2398[Abstract]
  35. Li PKT, Szeto CC, Law MC et al. Comparison of double-bag and Y-set disconnect systems in continuous ambulatory peritoneal dialysis: a randomised prospective multicenter study. Am J Kidney Dis1999; 33: 535–540[ISI][Medline]
  36. Begg C, Cho M, Eastwood S et al. Improving the quality of reporting of randomised controlled trials: the CONSORT statement. JAMA1996; 276: 637–639[ISI][Medline]
Received for publication: 13. 7.00
Accepted in revised form: 3. 8.00