Skip Navigation



NDT Advance Access published online on September 12, 2008
Nephrology Dialysis Transplantation, doi:10.1093/ndt/gfn372
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
23/12/4021    most recent
gfn372v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Fang, W.
Right arrow Articles by Oreopoulos, D. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Fang, W.
Right arrow Articles by Oreopoulos, D. G.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author [2008]. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved. For Permissions, please e-mail: journals.permissions@oxfordjournals.org


Comparison of peritoneal dialysis practice patterns and outcomes between a Canadian and a Chinese centre

Wei Fang1,2, Jiaqi Qian1, Aiwu Lin1, Fadel Rowaie2, Zhaohui Ni1, Qiang Yao1, Joanne M. Bargman2 and Dimitrios G. Oreopoulos2

1 Renal Division, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China 2 Peritoneal Dialysis Program, University Health Network and University of Toronto, Toronto, Ontario, Canada

Correspondence and offprint requests to: Dimitrios G. Oreopoulos, University Health Network, Toronto and University of Toronto, 399 Bathurst Street, Toronto, Ontario M5T 2S8, Canada. Tel: +416-603-7974; Fax: +416-603-5189. E-mail: dgo{at}teleglobal.ca; dimitrios.oreopoulos{at}uhn.on.ca



   Abstract
Top
 Abstract
Introduction
 Materials and methods
 Results
 Discussion
 References
 
Objective. We compared patient characteristics, dialysis practice patterns and outcomes of peritoneal dialysis (PD) patients between one Chinese centre and one Canadian centre to determine whether observed differences in demographics and practices are associated with patient and technique survival.

Methods. This study included all patients who started on PD between 1 January 2000 and 31 December 2004 at the University Health Network, University of Toronto, Canada and Renji Hospital, Shanghai Jiao Tong University School of Medicine, China. They were followed up from the date of PD initiation until death, cessation of PD, transfer to other centres or to the end of the study (31 December 2006).

Results. We studied 496 patients, 256 from the Canadian centre and 240 from the Chinese centre. Canadian patients were older and more likely to have diabetes and cardiovascular comorbidities at the initiation of PD, while the Chinese patients had lower residual renal function (RRF). More Canadian patients were treated with APD, whereas all Chinese patients were on CAPD with a lower PD volume. Crude patient survival rates at 1, 2, 3 and 5 years were similar between the two centres: 90%, 79%, 72% and 61% for Canadian and 90%, 79%, 71% and 64% for Chinese patients, respectively. After adjustment for demographic and clinical variables, there is no significant difference in mortality between Chinese patients and Canadian patients. Age, cardiovascular disease, diabetes, RRF and serum albumin were independent predictors of patient survival. The death-censored technique survival rates were significantly lower among the Canadian patients compared to Chinese patients. Chinese patients showed a lower risk of technique failure (HR 0.491, 95% CI 0.269–0.898, P = 0.021) after adjustment for patient characteristics. Chinese centre, BMI, serum albumin and gender were independent predictors of technique survival. The average peritonitis rate was one episode every 36.1 patient-months in Canadian patients and one episode every 60.6 patient-months in their Chinese counterparts.

Conclusion. Patient characteristics, dialysis practice patterns and outcomes vary between Canadian and Chinese patients. The variability in patient outcomes between these two centres indicates that further improvements may be possible in both centres. We have identified several areas for improving outcomes.

Keywords: mortality; peritoneal dialysis; peritonitis rate; risk factor; technique survival



   Introduction
Top
 Abstract
 Introduction
Materials and methods
 Results
 Discussion
 References
 
Outcomes among dialysis patients differ considerably between and within countries. Held et al. reported that, adjusted for age and diabetes, the mortality risk for the end-stage renal disease (ESRD) patients in the United States was 15% higher than in European patients and 33% higher than in Japanese patients [1]. Furthermore, after adjusting for age, gender, race and 25 comorbid conditions, Goodkin et al. reported that, compared to Japanese patients, the relative risk of mortality in haemodialysis (HD) patients in Europe was 2.84 and 3.78 for the United States [2]. The basis for and implications of this survival difference continues to be debated. In peritoneal dialysis (PD), on the other hand, Chung et al. compared survival between 106 Swedish and 132 Korean patients with a median follow-up of 18 months, and found no difference in patient outcome, both unadjusted and after adjusting for some patient and centre characteristics [3].

Survival on dialysis is affected by both treatment and patient characteristics. To date, we do not have international studies of long-term survival on PD containing extensive profiles of patient characteristics and outcomes. Therefore, we compared the patient characteristics, PD practice patterns and outcomes between two experienced university centres, one in China and one in Canada, to determine whether and to what extent these differences are associated with patient and technique survival. We believe that this study will provide evidence that may improve treatment of PD patients in both countries.



   Materials and methods
Top
 Abstract
 Introduction
 Materials and methods
Results
 Discussion
 References
 
Patients and data collection
All patients who started on PD between 1 January 2000 and 31 December 2004 at the University Health Network, University of Toronto, Canada, and Renji Hospital, Shanghai Jiao Tong University School of Medicine, China, were identified from administrative records. Data were collected regarding patient demographic characteristics, comorbid diseases, laboratory values and medical history. All deaths, switches to HD, transplantation, peritonitis episodes and other patient outcomes were carefully tracked and recorded.

We recorded data of initiation of dialysis, including age, gender, race (White, Asian, Black or other), height, weight, underlying cause of ESRD, date of initiation of dialysis, PD prescription (including PD volume and PD modality) and presence of comorbid diseases such as diabetes mellitus and cardiovascular disease (CVD) at the time of initiation of PD. Diabetes mellitus was defined either as a comorbid condition or as the aetiology of ESRD. CVD was defined as a previous history of coronary artery disease, peripheral vascular disease or cerebrovascular disease. Body mass index (BMI) was calculated as the weight (kg) divided by the square of height in metres [BMI = weight (kg)/height (m2)]. Blood pressure was measured by trained staff with a standard mercury sphygmomanometer. We collected baseline systolic and diastolic blood pressures and number of antihypertensive medications.

Dialysis adequacy data, namely indices of urea kinetics (Kt/Vurea) and creatinine clearance (CrCl) for both peritoneal and residual renal function (RRF), were documented using standard methods. Peritoneal transport characteristics were measured by the dialysate-to-plasma creatinine ratio (D/Pcr) at 4 h in a standard peritoneal equilibration test (PET). RRF, urine output and net effluent volumes were recorded. RRF was estimated by calculating the mean of renal clearances of urea and creatinine from a 24-h urine collection. Nutritional status was assessed by normalized protein catabolic rate (nPCR) from 24-h dialysate and urine collections. At the initiation of PD, the following laboratory parameters were also collected: haemoglobin, serum albumin, calcium, phosphate and intact parathyroid hormone (iPTH).

The total number of episodes of peritonitis and date of every episode of peritonitis were collected. For both centres, peritonitis rates were calculated by dividing the months of PD at risk by the number of episodes.

Detailed causes of death and transfer to HD were recorded from the clinical charts. Causes of death were grouped in broad categories as follows: cardiovascular, including cardiac, cerebrovascular, peripheral vascular and sudden death; infection, including peritonitis, pneumonia and other infections; other and unknown causes. Causes of switch to HD were grouped into peritonitis; catheter-related events including leak, hernia and catheter malposition; inadequate dialysis, including ultrafiltration failure/fluid management issues and other medical causes. All patients were followed up from the date of PD initiation until death, cessation of PD, transfer to other centres or to the end of the study (31 December 2006).

Statistical analyses
All results were expressed as mean ± SD for normally distributed data, median and range for skewed data and frequency (%) for categorical data. Differences in patient demographic, clinical and laboratory parameters between two centres were evaluated by Student's t-test for parametric data and the Mann–Whitney test for nonparametric data. Comparisons of percentages between groups were made with the chi-square test ({chi}2) or Fisher's exact test, as appropriate.

Actuarial cumulative survival rates were determined by using life table analysis. Survival curves were generated by the Kaplan–Meier method and compared by the log-rank test. Risk factors associated with mortality and technique failure were determined by univariate and then by a multivariate Cox proportional hazards model. A backward stepwise elimination multivariate Cox modelling analysis was performed to determine the independent predictors of patient outcome, and only covariates that remained significant (P < 0.05) were kept in the model. Data were censored at the following events: death, switch to HD, renal transplantation, transfer to other centre, recovery of renal function and loss to follow-up, with the exception of death for patient survival analysis, and the exception of switch to HD for death-censored technique calculation. In order to avoid the risk that patients doing poorly on PD and switched to HD as a pre-terminal event, we categorized patients who died within 3 months after being switched to HD as death on PD, and in this case, data were censored at the date of death for patient survival analysis. Also, time to the first peritonitis episode was examined using the Kaplan–Meier method and Cox regression models for multivariate analyses. Statistical analysis was performed using SPSS for Windows software, version 13.0 (SPSS Inc., Chicago, IL, USA). A P-value <0.05 was considered statistically significant.



   Results
Top
 Abstract
 Introduction
 Materials and methods
 Results
Discussion
 References
 
Demographic and clinical characteristics
A total of 496 patients were included, 256 from the Canadian centre and 240 from the Chinese centre. The main baseline demographic and clinical characteristics of the study populations are presented in Table 1. The Canadian patients had greater racial diversity, with 150 (58.6%) being White, 74 (28.9%) Asian, 21 (8.2%) Black and 11 (4.3%) other races. In comparison, all patients in the Chinese centre were Asian. Chinese patients were younger, had smaller BMI, were more likely to have glomerulonephritis and less likely to have diabetic nephropathy as the causes of ESRD and had fewer instances of CVD comorbidity compared to their Canadian counterparts. Chinese patients had higher blood pressure than that of Canadian patients at the commencement of PD, and they were prescribed more antihypertensive medications. Laboratory data showed that, compared to Canadian patients, Chinese patients were more anaemic, had lower serum albumin, marginally lower corrected calcium, higher serum phosphate and iPTH at the time of PD initiation.


View this table:
[in this window]
[in a new window]

  		Table 1 Demographic and baseline characteristics of the study patients

 
PD prescription and adequacy data
At the initiation of PD, Canadian patients had greater RRF than their Chinese counterparts (6.77 ± 4.43 versus 3.52 ± 2.67 ml/min, P < 0.001). They had a higher D/P creatinine ratio at 4 h in a standard PET (0.71 ± 0.09 versus 0.68 ± 0.13, P < 0.01) and were treated with significantly higher volumes of dialysis fluid than the Chinese patients (median 8.0 l versus 6.0 l, P < 0.001). The comparison of adequacy data showed that, compared with Chinese patients, Canadian patients had higher peritoneal Kt/Vurea, renal Kt/Vurea, peritoneal CrCl, renal CrCl and ultrafiltration whereas Chinese patients had higher urine output despite the lower RRF. There was no difference in nPCR and total daily fluid removal (Table 2).


View this table:
[in this window]
[in a new window]

  		Table 2 PD adequacy data between Canadian patients and Chinese patients

 
In Canadian patients, after the start, the PD modality was continuous ambulatory peritoneal dialysis (CAPD) with the twin-bag system in 99 (38.7%), automated peritoneal dialysis (APD) in 157 (61.3%) and icodextrin solution was used in 77 (30.1%). In comparison, all Chinese patients were treated with CAPD with the twin-bag system and without the icodextrin solution. Both centres were using dialysis solutions from the same supplier. During the follow-up, Chinese patients continued to be treated with significantly lower PD volumes compared to their Canadian counterparts (6.0 l versus 9.5 l at 2 years and 7.0 l versus 10.0 l at 4 years, respectively, both P < 0.001).

Clinical data during the follow-up
After 2 years on PD, Chinese patients were still more anaemic than Canadian patients, whereas serum albumin and phosphate were similar between the two groups. Parathyroid hormone was lower in Chinese than Canadian patients at 2 years. Among those who were treated with PD for >4 years, Chinese patients had lower haemoglobin, higher albumin and had better control of iPTH than that of Canadian patients (Table 3).


View this table:
[in this window]
[in a new window]

  		Table 3 Patient characteristics after PD for 2 and 4 years

 
Outcome
With a total follow-up of 15 176 patient-months, the mean follow-up was 29.9 ± 22.0 months (median 26.1 months) for Canadian patients and 31.5 ± 20.9 (median 29.3 months) for Chinese patients. By the end of the study, 69 (27.0%) Canadian and 65 (27.1%) Chinese patients had died; 43 (16.8%) Canadian and 32 (13.3%) Chinese patients had received a transplant; 40 (15.6%) Canadian and 20 (8.3%) Chinese patients had been transferred to HD; 20 (7.8%) Canadian and 7 (2.9%) Chinese were transferred to other centres and 7 (2.7%) Canadian and 2 (0.8%) Chinese patients spontaneously recovered renal function and ceased dialysis.

The causes of death are shown in Table 4. Cardiovascular death remained the most common cause of death in both centres, while infection was a greater cause of death among Canadian than Chinese (33.3% versus 15.4%, P = 0.016). Among the cardiovascular deaths, Chinese patients had more deaths caused by cerebrovascular disease (43.8% versus 17.2%, P = 0.026). Peritonitis accounted for more than one-half of the deaths due to infection and tended to cause more deaths in Canadian than Chinese patients (20.3% versus 9.2%, P = 0.073).


View this table:
[in this window]
[in a new window]

  		Table 4 Causes of death

 
Peritonitis was the most frequent cause of technique failure in both centres (Table 5), followed by catheter-related complications, inadequate dialysis and other medical problems. Although more Canadians were switched to HD, the distribution of different causes of technique failure was similar between the two centres.


View this table:
[in this window]
[in a new window]

  		Table 5 Causes of switch to HD

 
Patient survival and predictors of mortality
The unadjusted patient survival rates were similar in the two centres: 90%, 79%, 72% and 61% for Canadian and 90%, 79%, 71% and 64% for Chinese patients at 1, 2, 3 and 5 years, respectively. Figure 1 shows Kaplan–Meier survival curves for Canadian and Chinese patients (log rank 0.087, P = 0.768). After adjustment for age, gender, race, diabetes, BMI, CVD, RRF, serum albumin, haemoglobin and calcium x phosphate product, there is still no significant difference in mortality between Chinese patients and Canadian patients (P > 0.05). Multivariate Cox proportional hazards modelling showed that older age, CVD, lower RRF and lower serum albumin were independent predictors of increased mortality in the combined cohort. The results are summarized in Table 6. Age, CVD and serum albumin were the significant factors that independently predicted outcome in Canadian patients, whereas age, CVD and RRF were associated with death in Chinese patients.


Figure 1
View larger version (21K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 1 Kaplan–Meier survival curves for Canadian and Chinese patients and number of patients being followed at different time points.

 

View this table:
[in this window]
[in a new window]

  		Table 6 Predictors of mortality on Cox multivariate analysis

 
Death-censored technique survival and predictors of technique failure
The unadjusted death-censored technique survival rates at 1, 2, 3 and 5 years were 92%, 88%, 85% and 73% for Canadian patients and 97%, 93%, 90% and 88% for Chinese patients, respectively. Kaplan–Meier survival curves for Canadian and Chinese patients are shown in Figure 2. Chinese patients showed better death-censored technique survival than Canadian patients (log rank 5.947, P = 0.015). The advantage of technique survival in Chinese patients persisted (HR 0.491, 95% CI 0.269–0.898, P = 0.021) after adjustments for age, gender, race, diabetes, BMI and serum albumin. The multivariable Cox regression analysis showed that Chinese centre, lower BMI, higher albumin and male gender were independent predictors of better technique survival in the combined cohort (Table 7). We did not do further stratification of centres to avoid the potential risk of over-fitting in the multivariate model, because the total number of instances of switch to HD in either centre was low.


Figure 2
View larger version (22K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 2 Death-censored technique survival curves for Canadian and Chinese patients and number of patients being followed at different time points.

 

View this table:
[in this window]
[in a new window]

  		Table 7 Predictors of technique failure on Cox multivariate analysis

 
Peritonitis rate and predictors of peritonitis-free survival
During the study period, a total of 336 episodes of peritonitis were recorded, including 212 in Canadian patients and 124 in Chinese patients. The average peritonitis rate was one episode every 36.1 patient-months in Canadian patients and one episode every 60.6 patient-months in their Chinese counterparts. The median peritonitis-free time for Canadian patients was 34.2 months, which was significantly shorter than for Chinese patients, who had a median peritonitis-free time of 58.7 months (log rank 9.084, P = 0.003) (Figure 3).


Figure 3
View larger version (19K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 3 Probability of PD patients remaining free of peritonitis in Canadian and Chinese centre.

 
We further constructed a multivariate Cox proportional hazards model for the analysis of time to the first peritonitis episode. Chinese centre (HR 0.666, 95% CI 0.494–0.896, P = 0.007), higher albumin (HR 0.656, 95% CI 0.500–0.861, P = 0.002) and younger age (HR 1.128, 95% CI 1.003–1.233, P = 0.008) were found to be significantly associated with longer peritonitis-free survival among our combined cohort. After stratifying subjects according to different centres, serum albumin (HR 0.596, 95% CI 0.399–0.891, P = 0.012) was the only predictor that was associated with peritonitis-free survival in Chinese patients, whereas serum albumin (HR 0.618, 95% CI 0.423–0.904, P = 0.013), age (HR 1.162, 95% CI 1.043–1.295, P = 0.007) and BMI (HR 1.046, 95% CI 1.002–1.093, P = 0.042) were independent predictors of peritonitis-free survival in Canadian patients.



   Discussion
Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
References
 
The present study examined an extensive profile of patient characteristics, PD practice and outcomes in one Canadian and one Chinese centre. The results have allowed us to gain insights into the practice patterns as well as the potential causes for the differences in patient and technique outcomes in these two similar-sized centres.

The demographic and clinical characteristics of study patients varied between the Chinese centre and Canadian centre. The Canadian patients were older, heavier and more likely to have diabetes and cardiovascular comorbidities, findings indicating that the Canadian patients were sicker and carried a heavier burden of the most important comorbid diseases that predict a poor outcome at the initiation of PD. Chinese patients showed significantly lower RRF at the start of PD, suggesting that dialysis was commenced later in the Chinese patients. Consistent with the later commencement, Chinese patients showed a more adverse metabolic profile. However, after PD initiation, the clinical characteristics of Chinese patients improved, including nutritional and mineral metabolic parameters.

Besides the differences in patient characteristics, PD practice and dialysis adequacy were significantly different between the two centres. More than 60% of Canadian patients were treated with APD and 30% with the icodextrin solution, whereas all Chinese patients were treated with only CAPD and none was on icodextrin. Another notable difference was a significantly lower PD volume used in Chinese patients. Chinese patients had a smaller body size than their Canadian counterparts but, even allowing for this, the clearances delivered on PD were substantially lower in Chinese patients. Another interesting finding was that Canadian patients had more ultrafiltration than Chinese patients despite higher peritoneal permeability, which may be due to the icodextrin solution and cycler use, and possibly shorter dwell time among CAPD patients with four or more exchanges; however, their urine output was less than that of Chinese patients, resulting in similar daily fluid removal. This observation raised the question whether it is beneficial to allow adequate ultrafiltration at the expense of urine output; Gunal et al. showed that increasing ultrafiltration in CAPD patients could normalize blood pressure but resulted in a striking decrease in urine output [4]. On the other hand, whether Chinese patients were taking a higher dose of diuretics might be another possible explanation for the disproportionately higher urine output; however, data of diuretic use were not available in our study.

Similar to the report from Hong Kong [5], patient survival of the Chinese cohort in the present study was relatively good even with low doses of PD. Our study showed an almost identical crude patient survival rate between the two centres: 90%, 79%, 72% and 61% for Canadian and 90%, 79%, 71% and 64% for Chinese at 1, 2, 3 and 5 years, respectively. Both centres in the current study seem to have better patient survival than the data of US Renal Data System (USRDS) [6] and Canadian Organ Replacement Register (CORR) [7] but similar to the reports from the more wealthy Asian areas [5,8–10]. CVD is a frequent and important cause of morbidity and mortality in patients with ESRD [11,12]. Thus, it is not surprising that CVD accounted for up to 50% of all deaths in our study. However, while there was a higher prevalence of CVD at the start of PD in the Canadians compared with the Chinese, the number of cardiovascular deaths remained close between the two centres. One limitation of the current study was that it used only historic documentation of comorbid conditions, and quantitative measures for the severity of these conditions were not available. Thus, we do not know whether more Chinese patients developed de novo CVD after PD, or whether they had more aggressive disease. On the other hand, under-diagnosing CVD in Chinese patients could not be completely excluded. Szeto et al. reported that compared to the patients with RRF, anuric patients had a significantly higher CVD mortality, and patients without pre-existing CVD more commonly died of vascular disease after they became anuric [13]. Chinese patients in the present study had lower RRF compared to their Canadian counterparts, and this might partially explain why they had a lower prevalence of CVD at PD initiation but similarly high CVD mortality. Cox regression showed that CVD was associated with a higher risk for death in the Chinese patients than in Canadians, suggesting that the burden of CVD in Chinese patients might be heavier; additional studies are needed to determine optimal measures to prevent or intervene CVD in Chinese patients. On the other hand, Canadian patients had more infection-related deaths, the majority of which were due to peritonitis, indicating the importance of prevention and treatment of such complications in the Canadian patients. In accordance with previous studies [14–16], age, CVD, diabetes, RRF and serum albumin were independent determinants of patient survival.

Chinese patients had a higher death-censored technique survival than Canadians. In concordance with other studies [17,18], lower BMI and higher serum albumin levels were independent predictors of longer technique survival. Also, we found that female gender was a significant predictor of technique failure. It has been reported recently that females have an almost twice as high likelihood of developing severe peritonitis as males and a greater proportion of them have gram-negative bacilli as the causative organism [19,20]. This may partially explain our results although we did not find that female patients developed peritonitis earlier than males. The technique survival rate in the present Chinese cohort appears to be as good as, or even better than, that reported from Hong Kong, Japan and Korea [10,21–23]. One explanation for the superior technique survival observed in Chinese patients might be their lower peritonitis rate that was remarkably low. Chinese patients had significantly longer peritonitis-free survival than their Canadian counterparts. Secondly, it may be due to the fact that Chinese patients generally were healthier, were younger and had less comorbidity, and so were more able to carry on with PD even in the face of complications such as peritonitis. An alternative explanation is that social reasons may underlie the superior technique survival. A study of CAPD compliance in North America showed that ethnic background was a strong predictor of noncompliance [24]. That is, while 13% of the population as a whole admitted noncompliance, the figure was 9% for Caucasians, 28% for African Americans, but only 3% for Asians. Better compliance may explain at least some of the superior technique survival noted among Chinese patients in this study. Similarly, increased family and social support may produce improved technique survival among Chinese patients [25]. Both centres in the present study have large HD programmes; thus, the availability of HD transfer does not likely explain the difference in technique survival. On the other hand, the threshold for transferring a patient from PD to HD might affect technique survival. However, we don't have data on this aspect of care.

Consistent with other studies [26–28], in our study cohort peritonitis not only was the leading cause of technique failure but also contributed to mortality. The Chinese patients had a remarkably lower peritonitis rate than that of Canadian patients. Therefore, the Canadian patients had higher risk of mortality and technique failure due to peritonitis compared to the Chinese patients. Our results confirmed the susceptibility of elderly and hypoalbuminemic patients to peritonitis [29,30]. Renji centre has a good record system of peritonitis both in computer and charts, and none of the patients in this centre had been trained to intraperitoneal use of antibiotics, being unable to treat themselves when peritonitis occured; therefore, under-reporting likely does not explain the superior peritonitis rate in Chinese patients. We do not know all the factors that contribute to the lower peritonitis rate in the Chinese patients. Perhaps the Chinese patients generally are healthier and have less comorbidity, and so may have stronger defence functions against peritonitis. Another possible explanation is that Chinese patients were dialyzed with fewer exchanges, which might reduce the opportunity of bacteria contamination. In addition, it has been reported that the risk for peritonitis is lower for CAPD than for APD (RR 0.939), which may partially explain the lower peritonitis rate in the Chinese patients [31]. Similar to the technique survival, patient compliance and family support might have a role in the better peritonitis rate in Chinese patients [32]. Finally, genetic factors may explain the differential susceptibility to peritonitis of Canadian and Chinese patients but this remains to be elucidated.

In summary, the present study that compared detailed PD data between one Chinese centre and one Canadian centre showed that patient and treatment characteristics varied between these two centres. Chinese patients were dialyzed with a significantly lower dose. There is no significant difference in mortality between Chinese patients and Canadian patients. Chinese patients had better technique survival both unadjusted and adjusted, probably due to a lower peritonitis rate and generally healthier status than their Canadian counterparts. Several questions might be raised based on these results: Could the peritonitis rate in Canadian patients be improved by concentrating on compliance and possibly fewer exchanges? Will the introduction of the icodextrin solution and cycler dialysis improve the survival in Chinese patients? Clearly additional studies are warranted to address all these questions.

Our study has several obvious limitations. It is a retrospective study and therefore ascertainment error, recall, informative censoring and lead-time biases cannot be avoided. Only one centre each with a limited number of patients from the two countries was included, so it may be difficult to extrapolate the results to all Chinese and Canadian PD patients. Also, we do not know the proportions of patients who started renal replacement therapy with PD in both centres. However, we believe that patients from the two centres do not deviate substantially from the respective national PD population. Although we have analysed relatively detailed information about patient characteristics and practice patterns in survival analysis, other unknown or residual confounders may still exist. In addition, no data are available for other potentially important end points such as deterioration of RRF, cardiovascular events or number of hospitalizations.

We conclude that patient characteristics, dialysis practice patterns and outcomes differed between the Canadian centre and Chinese centre. The difference in patient outcome between centres indicates that further improvements are possible in both centres.



   Acknowledgments
 
We would like to thank Sharron Izatt, Judi Shea, Ying Hang, Xiaojuan Zhang and nurses of both centres for maintenance of the patients’ data and assistance in data collection.

Conflict of interest statement. None declared.



   References
Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 

  1. Held PJ, Brunner F, Odaka M, et al. Five-year survival for end-stage renal disease patients in the United States, Europe, and Japan, 1982 to 1987. Am J Kidney Dis (1990) 15:451–457.[Web of Science][Medline]
  2. Goodkin DA, Bragg-Gresham JL, Koenig KG, et al. Association of comorbid conditions and mortality in hemodialysis patients in Europe, Japan, and the United States: the Dialysis Outcomes and Practice Patterns Study (DOPPS). J Am Soc Nephrol (2003) 14:3270–3277.[Abstract/Free Full Text]
  3. Chung SH, Heimburger O, Lindholm B, et al. Peritoneal dialysis patient survival: a comparison between a Swedish and a Korean centre. Nephrol Dial Transplant (2005) 20:1207–1213.[Abstract/Free Full Text]
  4. Gunal AI, Duman S, Ozkahya M, et al. Strict volume control normalizes hypertension in peritoneal dialysis patients. Am J Kidney Dis (2001) 37:588–593.[Web of Science][Medline]
  5. Lo WK, Jiang Y, Cheng SW, et al. Survival of CAPD patients in a center using three two-liter exchanges as standard regime. Perit Dial Int (1996) 16(Suppl_1):S163–S166.[Abstract]
  6. US renal Data System. 2006 Annual Data Report (2006) Bethesda, MD: the National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Disease.
  7. Canadian Institute for Health Information. Treatment of end-stage organ failure in Canada, 1995–2004. (2006 Annual Report) Ottawa: The Institute 2006.
  8. Shinzato T, Nakai S, Akiba T, et al. Report of the annual statistical survey of the Japanese Society for Dialysis Therapy in 1996. Kidney Int (1999) 55:700–712.[CrossRef][Web of Science][Medline]
  9. Han DS, Hwang JH, Kang DH, et al. Current status of peritoneal dialysis in Korea: efforts to achieve optimal outcome. Perit Dial Int (1999) 19(Suppl 3):S17–S25.[Abstract/Free Full Text]
  10. Han SH, Lee SC, Ahn SV, et al. Improving outcome of CAPD: twenty-five years’ experience in a single Korean center. Perit Dial Int (2007) 27:432–440.[Abstract/Free Full Text]
  11. Wheeler DC. Cardiovascular disease in patients with chronic renal failure. Lancet (1996) 348:1673–1674.[CrossRef][Web of Science][Medline]
  12. London GM, Drueke TB. Atherosclerosis and arteriosclerosis in chronic renal failure. Kidney Int (1997) 51:1678–1695.[Web of Science][Medline]
  13. Szeto CC, Wong TY, Chow KM, et al. Are peritoneal dialysis patients with and without residual renal function equivalent for survival study? Insight from a retrospective review of the cause of death. Nephrol Dial Transplant (2003) 18:977–982.[Abstract/Free Full Text]
  14. Paniagua R, Amato D, Vonesh E, et alMexican Nephrology Collaborative Study Group. Effects of increased peritoneal clearances on mortality rates in peritoneal dialysis: ADEMEX, a prospective, randomized, controlled trial. J Am Soc Nephrol (2002) 13:1307–1320.[Abstract/Free Full Text]
  15. Bargman JM, Thorpe KE, Churchill DN. CANUSA Peritoneal Dialysis Study Group. Relative contribution of residual renal function and peritoneal clearance to adequacy of dialysis: a reanalysis of the CANUSA study. J Am Soc Nephrol (2001) 12:2158–2162.[Abstract/Free Full Text]
  16. Churchill DN, Taylor DW, Keshaviah PR. for the CANUSA Peritoneal Dialysis Study Group. Adequacy of dialysis and nutrition in continuous peritoneal dialysis: association with clinical outcomes. J Am Soc Nephrol (1996) 7:198–207.[Abstract]
  17. McDonald SP, Collins JF, Johnson DW. Obesity is associated with worse peritoneal dialysis outcomes in the Australia and New Zealand patient populations. J Am Soc Nephrol (2003) 14:2894–2901.[Abstract/Free Full Text]
  18. Blake PG, Flowerdew G, Blake RM, et al. Serum albumin in patients on continuous ambulatory peritoneal dialysis—predictors and correlations with outcomes. J Am Soc Nephrol (1993) 3:1501–1507.[Abstract]
  19. Kotsanas D, Polkinghorne KR, Korman TM, et al. Risk factors for peritoneal dialysis-related peritonitis: can we reduce the incidence and improve patient selection? Nephrology (2007) 12:239–245.[CrossRef][Medline]
  20. Perez Fontan M, Rodriguez-Carmona A, Garcia-Naveiro R, et al. Peritonitis-related mortality in patients undergoing chronic peritoneal dialysis. Perit Dial Int (2005) 25:274–284.[Abstract/Free Full Text]
  21. Lam MF, Tang C, Wong AK, et al. ASPD: a prospective study of adequacy in Asian patients on long term, small volume, continuous ambulatory peritoneal dialysis. Perit Dial Int (2006) 26:466–474.[Abstract/Free Full Text]
  22. Nakamoto H, Kawaguchi Y, Suzuki H. Is technique survival on peritoneal dialysis better in Japan? Perit Dial Int (2006) 26:136–143.[Abstract/Free Full Text]
  23. Han DS, Hwang JH, Kang DH, et al. Current status of peritoneal dialysis in Korea: efforts to achieve optimal outcome. Perit Dial Int (1999) 19(Suppl 3):S17–S25.[Abstract/Free Full Text]
  24. Blake PG, Korbet SM, Blake R, et al. A multicenter study of noncompliance with continuous ambulatory peritoneal dialysis exchanges in US and Canadian patients. Am J Kidney Dis (2000) 35:506–514.[Medline]
  25. Holroyd EE. Chinese family obligations toward chronically ill elderly members: comparing caregivers in Beijing and Hong Kong. Qual Health Res (2003) 13:302–318.[Abstract/Free Full Text]
  26. Mastrosimone S, Virga G, Gastaldon F, et al. Low peritonitis rate leads to high patient survival and technique success: the first five years of a peritoneal dialysis program. Perit Dial Int (2002) 22:91–93.[Free Full Text]
  27. Schaubel DE, Blake PG, Fenton SS. Trends in CAPD technique failure: Canada, 1981–1997. Perit Dial Int (2001) 21:365–371.[Abstract/Free Full Text]
  28. Perez Fontan M, Rodriguez-Carmona A, Garcia-Naveiro R, et al. Peritonitis-related mortality in patients undergoing chronic peritoneal dialysis. Perit Dial Int (2005) 25:274–284.[Abstract/Free Full Text]
  29. Wang Q, Bernardini J, Piraino B, et al. Albumin at the start of peritoneal dialysis predicts the development of peritonitis. Am J Kidney Dis (2003) 41:664–669.[CrossRef][Web of Science][Medline]
  30. Chow KM, Szeto CC, Leung CB, et al. A risk analysis of continuous ambulatory peritoneal dialysis-related peritonitis. Perit Dial Int (2005) 25:374–379.[Abstract/Free Full Text]
  31. Oo TN, Roberts TL, Collins AJ. A comparison of peritonitis rates from the United States renal data system database: CAPD versus continuous cycling peritoneal dialysis patients. Am J Kidney Dis (2005) 45:372–380.[CrossRef][Web of Science][Medline]
  32. Verger C, Duman M, Durand PY, et al. Influence of autonomy and type of home assistance on the prevention of peritonitis in assisted automated peritoneal dialysis patients. An analysis of data from the French language peritoneal dialysis registry. Nephrol Dial Transplant (2007) 22:1218–1223.[Abstract/Free Full Text]
Received for publication: 9.11.07
Accepted in revised form: 10. 6.08


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?



This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
23/12/4021    most recent
gfn372v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Fang, W.
Right arrow Articles by Oreopoulos, D. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Fang, W.
Right arrow Articles by Oreopoulos, D. G.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?