In the past 30 yr, the number of patients with treated ESRD has progressively increased. Given the paucity of organ donors, maintenance dialysis is the dominant form of treatment for ESRD, and it is estimated that in 2004, more than 1.3 million patients were undergoing some form of dialysis treatment worldwide (1). The incidence and prevalence rates for treated ESRD vary widely among various parts of the world; these differences seem to be, in large part, a reflection of the availability of financial support for renal replacement therapies (1). The United States and Japan account for almost one half of all of the maintenance dialysis patients worldwide (2). Renal replacement therapies are provided at an enormous financial cost. In 2003, the ESRD program cost US Medicare approximately $18.3 billion, and the total ESRD costs exceeded $30 billion (2). These costs are likely to continue to go up: In the United States, the ESRD population is projected to exceed 700,000 by 2015 (3). In Australia, the cumulative discounted total cost of renal replacement therapy (RRT) for all current and new patients with ESRD will be approximately $3.4 billion in today's currency by the end of this decade, rising to almost $5.1 billion by 2019 (4). Despite these high costs, these individuals experience poor rehabilitation, high hospitalization rates, and increased mortality (2). In the United States, approximately two thirds of all dialysis patients die within 5 yr of initiation of dialysis treatment, a 5-yr survival that is worse than that experienced by many patients with cancer (2).
More than 80% of dialysis patients are treated with maintenance hemodialysis (MHD), and peritoneal dialysis (PD) is the dominant modality for home dialysis (1). Since the introduction of continuous ambulatory PD, studies have explored the question of whether dialysis modality per se independently affects patient outcomes, including an early attempt at a randomized, controlled trial (5–7). In this review, we present our analysis of the current state of knowledge about the effects of dialysis modality on patient outcomes in context of the declining proportion of patients who undergo PD in many parts of the world.
Declining Use of PD
The striking variation in the proportion of patients who undergo PD in various parts of the world has been repeatedly analyzed (8–10). The relative use of different dialysis modalities has substantial cost implications. Studies have repeatedly shown that the payor costs for PD are lower than that for MHD. In a recent analysis of a random sample of Medicare recipients (11), even after adjustment for the younger age and lower comorbidity, the annual cost for PD patients were $12,000 lower than that for MHD patients. When a switch from PD to MHD was made in the first 3 yr, cost savings decreased to $10,000 but increased to $20,000 when no switch was made. Overall, the cost advantage of PD persisted even when the higher probability of transfer of PD patients to MHD was accounted for. Similar cost advantages have been demonstrated in Australia, where the annual cost for home HD was $38,028, for long-term PD was $48,303, and for hospital MHD was $70,349 (4). Thus, a higher use of PD has the potential to result in substantial cost savings, and understanding the causes of varying PD use has potentially significant public health implications (12). In addition to the cost advantages, patients who select PD report a greater satisfaction with care; this is very likely to be a result of education and training that go with the selection of the dialysis modality (13). These observations strengthen the case for greater use of PD.
Studies from Europe and North America indicate that more than two thirds of incident patients do not have a medical contraindication for either MHD or PD (14–17). These findings are consistent with the notion put forth more than a decade ago that modality selection is dictated largely by nonmedical factors (8). In the United States, the initiation of PD has historically been low and has never exceeded 15 to 16% of incident or prevalent maintenance dialysis patients (18). Surveys (19) of US academic medical centers indicated that many training programs do not have sufficient number of patients or devote enough time for fellows to develop expertise in the care of PD patients; more than half of practicing nephrologists in the United States reported that they were trained mainly in providing care for MHD patients (20,21). Similarly, most incident dialysis patients reported that PD was not offered to them as a RRT (17,22). Surprising, the probability of offering PD as a method of treatment for ESRD was not related to the presence of medical contraindications to the therapy (17). Finally, more than half of the dialysis units in the United States do not have the infrastructure to support PD. Paradoxic, geographic areas that are likely to benefit the most from availability of home dialysis—rural and remote rural areas—are the least likely to have the infrastructure for home dialysis (23). Furthermore, industry experts estimate that 20% of nephrologists provide care to 80% of PD patients in the United States; PD became and has remained a “niche” rather than a “mainstream” RRT (18). These observations point to an overall substantial lack of enthusiasm for PD among providers in the United States and probably explains the low initiation rate for the therapy.
Against this background of low use, the proportion of patients who undergo PD has declined further in the past decade in the United States (Figure 1) (2,18), and a >50% decline in the proportion of incident patients who commence treatment with PD has occurred (24). The United States is not the only country with declining use of PD. It is a phenomenon seen in North America and Australia and New Zealand; trends in Europe are more varied (Figures 2 and 3) (2). The reasons for this decline remain speculative, and some of the proposed hypotheses are summarized in Table 1. Of the proposed hypotheses, only the relationship of increasing age, body size, and comorbidity burden of incident dialysis patients has been studied. During an 8-yr period, starting from 1996, the age and body size of the incident dialysis patient in the United States increased, but the burden of coexisting illnesses did not change (24). Furthermore, PD use declined in every age group and strata of body size and coexisting illnesses (24); therefore, the change in age, body size, and coexisting disease burden are insufficient to explain the decrease in PD use in the United States. The systematic decline in use is likely a result of system-wide factors in the delivery of care (Table 1). Rapid increase in the number of MHD facilities; expansion of the preexisting clinics by increasing the number of HD stations; and increase in the number of HD shifts, including adding early morning, late evening, or overnight shifts, all may have translated into greater use of MHD. There is a need to test each of these hypotheses to explain the continuing decline in PD use in many parts of the world.
Comparative Survival Data between MHD and PD
The best study design to determine whether the dialysis modality has an independent effect on survival is a randomized, controlled trial; however, to randomly assign patients to two therapies with such disparate effects on their lifestyle is an uphill task. This was aptly demonstrated by the recent attempt undertaken as a part of the Netherlands Co-operative Study on Dialysis (NECOSAD); when patients were educated about the two dialysis modalities, more than 90% of the eligible patients wanted a choice in the selection of the RRT and refused to be randomly assigned (25). It is unlikely that another randomized, controlled trial will be attempted any time soon; therefore, one has to depend on observational studies for intermodality comparisons.
For the first 20 yr after the introduction of continuous ambulatory PD, numerous single-center and regional studies attempted to compare the outcomes in PD and MHD (26). Although the results of these studies were variable, the emerging consensus seemed to be that the outcomes with both of the modalities were similar; however, a study from the US Renal Data System raised questions about this assumption: In that analysis of comparative outcomes of prevalent MHD and PD patients with 170,700 patient-years of follow-up, the death rate for PD patients was 19% higher than that for MHD patients (27). Studies that were conducted in the past decade clearly demonstrated that there is a significant interaction between dialysis vintage and modality (28,29). In other words, the risk for death for PD patients, relative to that for MHD patients, changes over time. It follows, then, that using a prevalent cohort of patients, as used in this study, may have been inappropriate, and an optimal comparison would entail a prospective study of incident dialysis patients.
Several large studies (28,30–37) of incident dialysis patients have since been conducted, and the key studies are summarized in Table 2. Even though some of the findings differed between the various studies, intermodality comparisons using registries from various parts of the world may allow one to conclude that patients who undergo PD may have a survival advantage during the first few years of RRT; the magnitude and duration of time for this advantage seems to be affected by the patient's age, diabetic status, and the presence or absence of other coexisting illnesses. Generally, the lower the disease burden (viz, young patients without diabetes or other coexisting illnesses), the greater the apparent survival advantage seen with PD. Conversely, the greater the disease burden (viz, older patients with diabetes and other coexisting illnesses), the lower the apparent benefit with PD; however, it must be emphasized yet again that these registry comparisons are fraught with significant limitations: The assignment of patients to modality is nonrandom, and the comorbidity or laboratory data in large registries are often limited. The registries with more detailed data, such as the Danish registry, generally have the smallest number of patients (35); therefore, it remains unclear whether any of the outcome differences are causal and attributable to the dialysis modality. Nevertheless, in the context of this discussion, the data from registry studies summarized in Table 2 suggest that PD is associated with outcomes that are at least equivalent for most subgroups of incident patients.
In an apparent attempt to overcome some of the limitations of the registry studies, the Choices for Healthy Outcomes in Caring for ESRD (CHOICE) study was launched as a prospective, cohort study of comparisons of outcomes between MHD and PD patients (34). The CHOICE investigators reported no difference between outcomes during the first year, but in the second year, PD patients had a significantly increased risk for death (34). Although the efforts of these investigators were laudable, the study included only 1041 patients, substantially lower than the registry studies. Because the PD patients were selected from relatively fewer dialysis programs than the MHD patients, some have questioned the external validity of the study (38). Furthermore, concern has been raised that the multivariate models in the study may be overadjusted. Using overadjusted models is not a trivial problem, because systematic differences in laboratory parameters may be the result of the dialysis modality itself. For example, serum C-reactive protein was measured after an average of 5 mo after the first dialysis treatment (34). The serum C-reactive protein was higher among MHD patients, and it is possible that this difference may be a function of the dialysis modality (viz, greater systemic inflammation arising from the use of tunneled venous catheters). Finally, the findings of this study are inconsistent with virtually all registry studies of incident patients (Table 2).
A review of Table 2 also demonstrates that most of the studies included cohorts largely from the 1980s and 1990s; only one included patients who were incident after 2000. There are data to suggest that the outcomes of MHD and PD patients may have differentially changed during this period (24). In an analysis of the US Renal Data System data during an 8-yr period (1996 to 2003), the 12-mo outcomes of 606,777 incident patients were studied. The hazards for either death or transfer to MHD during 12 mo progressively decreased from 1996 to 1997 to 2002 to 2003, largely as a reduction in mortality (24). This improvement in outcomes of long-term PD patients was confirmed on multivariate analyses; using 1996 to 1997 as a reference, the hazard ratio for technique failure progressively decreased (Figure 4). In contrast, the outcomes of MHD patients remained largely unchanged during the same period (Figure 4) (24). Given these differential change in outcomes among patients who were treated with the two dialysis modalities, the intermodality comparisons need to be reexamined using a more contemporary cohort.
It is possible that the differential change in outcomes may be a result of more stringent criteria used to select patients who embark on PD therapy in the United States; however, many changes could also account for a greater improvement in outcomes of PD patients. For example, there has been a progressive reduction in peritonitis rates, largely because of a greater use of disconnect systems and use of exit-site antibiotic prophylaxis (39,40). Furthermore, many more centers are using continuous quality improvement programs that may have led to these improvements. Finally, there has been a greater use of automated PD that may, in part, account for the better PD outcomes; however, the role of these and other changes in the improved outcomes remains speculative and needs to be tested in future studies.
Possible Biologic Explanations for Differences in Outcomes by Modality
If one is to accept the notion that treatment with PD may be associated with an early survival advantage in some patient subgroups, then an important question that follows is, “Is it biologically plausible?” The leading hypothesis to explain the lower mortality among PD patients in the first few years relates to its salutary effect on residual renal function.
The relationship between residual renal function and survival of prevalent PD patients, first reported by Maiorca et al. (41), has now been repeatedly confirmed (42–46). These findings were further corroborated by the re-analysis of the Canada-USA (CANUSA) study wherein each 5-L/wk per 1.73 m2 higher mean of urea and creatinine clearances was associated with a 12% decrease in the relative risk for death (47). The remarkable consistency of these observations provides evidence for the importance of residual renal function to outcomes of PD patients.
The effect of residual renal function on outcomes for MHD patients is not as well studied. In a single-center study of 114 MHD patients, the presence of residual renal function was demonstrated to be protective during a 2-yr period (48). More recently, in a prospective study of 740 incident MHD patients, residual renal function was measured 3 mo after first dialysis treatment and then at 6-mo intervals. Using time-dependent models, during a median follow-up of 1.7 yr, every unit of residual renal Kt/Vurea was associated with 66% lower adjusted hazard for death (49). This magnitude of effect of residual renal function on survival is not unlike that seen among patients who undergo PD.
The foregoing discussion underscores the importance of residual renal function on outcomes of maintenance dialysis patients, irrespective of dialysis modality. Numerous studies have compared the rate of loss of residual renal function in MHD and PD patients, and the key studies (50–56) are summarized in Table 3. All but one study (53) demonstrated the relative advantage of PD over MHD in the preservation of residual renal function, even when one accounts for informative censoring. The participants who were undergoing MHD and enrolled in the only study that demonstrated equivalent rates of loss of residual renal function were treated with ultrapure water, a therapy that is not widely available (56). Thus, the preponderance of evidence suggests that PD is associated with slower rate of loss of residual renal function, and this may explain the consistent, early survival advantage in favor of PD in many subgroups of incident patients; however, the practice of both MHD and PD has changed, and comparisons using a more contemporary cohort is needed.
Alternatively, the early survival advantage of PD patients may be a result of a higher risk for early death among MHD patients. Sicker patients are more likely to commence MHD rather than PD, and the differences in outcomes may be a result of residual confounding. Furthermore, in the past decade, the proportion of MHD patients with a tunneled venous catheter increased, and along with it has been an exponential increase in the hospitalization of these patients with septicemia (2,57). Moreover, patients who experience a single episode of septicemia have a higher risk for death, myocardial infarction, peripheral vascular disease, and stroke (58). During the same period, the risk for infectious complications among PD patients decreased. Given that most MHD patients in the United States begin maintenance dialysis with a venous catheter, the survival advantage for PD patients may be a result of the lower risk for serious, systemic infectious (59).
With increasing dialysis vintage, the survival advantage of PD diminishes, and some subgroups seem to experience a higher risk for death. This change in relative risk may result from a change in the characteristics of the two cohorts. Thus, the sickest MHD patients experience early mortality, which may be further exacerbated by the infectious risk imposed by venous catheters. Conversely, the transplantation rate of PD patients is more than twice as much as that of MHD patients in the early period after the start of RRT (24). This, in turn, may remove the healthiest patients from the PD cohort. These two processes may result in the change in relative risk over time between the two modalities.
The leading hypothesis to explain the increase in relative risk for death for PD patients postulates that with increasing dialysis vintage, PD patients become volume overloaded (60,61). Single-center studies suggested that patients who were treated with continuous ambulatory PD had greater worsening of their volume status with increasing dialysis vintage than MHD patients. In addition to the loss of residual renal function, bio-incompatible PD solutions may lead to alterations in the peritoneal membrane that further accentuate volume overload. The high concentrations of glucose in conventional peritoneal dialysis fluids, along with glucose degradation products that are generated during heat sterilization, damage the peritoneal membrane, either directly or through the formation of advanced glycosylation end products. The structural changes often include an increase in capillary density and, thus, the effective peritoneal surface area, leading to an increase in peritoneal transport rate (62). This, in turn, leads to reduced peritoneal ultrafiltration capacity, particularly with continuous ambulatory PD using conventional glucose-based fluids (62). These peritoneal changes, coupled with loss of residual renal function, probably underlie the high prevalence of volume overload seen in many PD patients. Several studies (63–65) have shown an inverse relationship between daily peritoneal ultrafiltration volume and mortality, data that are consistent with the notion that reduced ultrafiltration capacity and consequent hypervolemia with increasing dialysis vintage may reverse the early survival advantage with PD.
It has also been argued that, in addition to local changes in the peritoneum, continued exposure to conventional PD solutions may have adverse systemic consequences. The continued absorption of glucose from PD solutions has been implicated in weight gain (generally fat), dyslipidemia, and hyperleptinemia. One recent study of 200 patients with stages 4 to 5 chronic kidney disease reported that PD was independently predictive of development of the metabolic syndrome (66). Post hoc analyses of the Euro-Balance trial (67) demonstrated that treatment with a new PD solution with very low concentrations of glucose degradation products may slow the rate of loss of residual renal function. Furthermore, a retrospective study (68) showed a survival advantage among PD patients who were treated with more physiologic dialysis fluids. In that study, the use of PD solutions was nonrandom, and there was lack of stratification or adjustment for cardiovascular disease, hypertension, socioeconomic status, and center. Finally, 305 patients who had a favorable prognosis and converted from conventional PD solutions to those with low concentrations of glucose degradation products were excluded from the analyses. Nevertheless, these observations are important in generating new hypotheses to be tested in clinical trials (69).
Relationship of Risk Factors to Outcomes May Differ among MHD and PD: Caution against Extrapolation
Notwithstanding the various risks that are observed over time with different dialysis modalities, the need for reducing cardiovascular risk among both MHD and PD patients is widely acknowledged; however, how to devise a risk reduction strategy remains undefined. This is related, in part, to numerous studies that demonstrated that the relationship of traditional cardiovascular risk factors to outcomes may be reversed in patients who undergo maintenance dialysis—the so-called “reverse epidemiology” (70). The confounding influence of inflammation can probably explain the reversal of association for some but not all of these risk factors that are deemed to be important in the general population (71). Moreover, interventions that have been consistently shown to be effective in the general population do not produce predictable results in maintenance dialysis patients: Whereas lipid-lowering therapy failed to improve outcomes among MHD patients with diabetes, treatment with carvedilol improved survival among MHD patients with dilated cardiomyopathy (72,73); therefore, although it may be prudent to use interventions that have been demonstrated to be consistently effective in the general population, it is possible that the same advantages may not accrue among maintenance dialysis patients.
Similarly, the relationship of risk factors to outcomes may differ between MHD and PD patients, exemplified by disparate results that were obtained in the studies that evaluated the relationship of body size to outcomes in MHD and PD patients (74,75). As summarized in Table 4, virtually all studies demonstrated that there is an inverse relationship between body size and patient outcomes in MHD patients, very likely a result of a higher body fat (76–88). Conversely, no such consistent findings have been reported among PD patients (85,86,89–92). Some studies have shown that obese patients have a survival advantage; others have shown an increased risk (91,92). Still other studies have shown no relationship between body size and outcomes of PD patients (85,86). These differences in relationship of body size to outcomes may be related to disparate metabolic conditions associated with the two modalities; therefore, one has to be careful in extrapolating data that were obtained from MHD patients to those who undergo PD.
Focus on the Future: Efforts to Continue to Improve Outcomes of Maintenance Dialysis Patients
On the basis of this discussion, it can be reasonably concluded that neither the differences in outcomes between PD and MHD patients are large enough nor are the data strong enough to implicate that these differences are causally related to the selected dialysis modality. It follows, then, that the outcome studies cannot be used to deny patients with ESRD a choice in the selection of dialysis modality. The processes discussed should, however, form the basis for devising future studies or management strategies with the potential to improve the outcomes of both MHD and PD patients; therefore, all efforts should be made to minimize the use of venous catheters or to reduce the risk for infections that are associated with use of catheters among patients who undergo MHD. Efforts to preserve residual renal function are likely to be beneficial for both MHD and PD patients. Randomized, controlled trials have demonstrated that angiotensin-converting enzyme inhibitors or angiotensin receptor blockers are renoprotective among PD patients (93,94). Even though there is no evidence that slowing the rate of decline of residual renal function translates into a survival benefit for maintenance dialysis patients, a controlled trial to test this hypothesis is probably unethical. Careful monitoring of volume status and achievement of euvolemia seem to be reasonable goals for both MHD and PD patients; however, numerous challenges remain in this field. Even though a large number of tools have been used to ascertain the volume status of maintenance dialysis patients, there is a paucity of controlled data to demonstrate that any of the noninvasive assessments can be used to guide therapy. There are significant ethical considerations, however, in the design of such a clinical trial, and attaining euvolemia should be attempted in all patients who undergo dialysis. Finally, numerous advances have been made in developing new PD solutions, but other than icodextrin, in the present regulatory environment, no other new PD solution is likely to be introduced in the United States at any time in the near future. The process for approval of new dialysis solutions needs to be re-evaluated. In addition, controlled clinical trials are needed to test the putative local peritoneal and systemic benefits of the new PD solutions in humans.
This discussion highlights the complexity of intermodality comparisons. Nevertheless, most studies demonstrate an early survival benefit among many subgroups of patients who are treated with PD, a benefit that likely is attributable to better preservation of residual renal function. Many studies also demonstrate an increase in relative risk for death among PD patients with increasing dialysis vintage, a risk that may be a result of worsening volume status. These observations allow us both to develop new hypotheses to be tested in clinical trials and to devise management strategies with the aim of improving outcomes of maintenance dialysis patients.
D.J. has served as a consultant for and received honoraria, travel sponsorship, and research support from Baxter Health Care and Fresenius Medical Care. R.M. has received honoraria and research support from Baxter Health Care and serves as a consultant for Novartis Pharmaceuticals.
This work was supported, in part, by grants from the National Institutes of Health (RR18298, R.M.), Satellite Health (R.M.), and DaVita (K.K.Z. and R.M.).
Published online ahead of print. Publication date available at www.cjasn.org.
1. Grassmann A, Gioberge S, Moeller S, Brown G: ESRD patients in 2004: Global overview of patient numbers, treatment modalities and associated trends. Nephrol Dial Transplant20 :2587– 2593,2005
2. US Renal Data System: Annual data report. Bethesda, US Department of Health and Human Services, Public Health Service, National Institutes of Health,2006
3. Gilbertson DT, Liu J, Xue JL, Louis TA, Solid CA, Ebben JP, Collins AJ: Projecting the number of patients with end-stage renal disease in the United States to the year 2015. J Am Soc Nephrol16 :3736– 3741,2005
4. Cass A, Chadban S, Craig J, Howard H, McDonald S, Salkeld G, White S: The Economic Impact of End-Stage Kidney Disease in Australia, Melbourne, Kidney Health Australia,2006
5. Popovich RP, Moncrief JW, Dechert JF, Pyle WK, Morris S, Lindley JD: The definition of a portable/wearable equilibrium dialysis technique [Abstract]. Trans Am Soc Artif Int Org5 :64 ,1976
6. Nolph KD, Sorkin M, Rubin J, Arfania D, Prowant B, Fruto L, Kennedy D: Continuous ambulatory peritoneal dialysis: Three-year experience at one center. Ann Intern Med92 :609– 613,1980
7. Gutman RA, Blumenkrantz MJ, Chan YK, Barbour GL, Gandhi VC, Shen FH, Tucker T, Murawski BJ, Coburn JW, Curtis FK: Controlled comparison of hemodialysis and peritoneal dialysis: Veterans Administration multicenter study. Kidney Int26 :459– 470,1984
8. Nissenson AR, Prichard SS, Cheng IK, Gokal R, Kubota M, Maiorca R, Riella MC, Rottembourg J, Stewart JH: Non-medical factors that impact on ESRD modality selection. Kidney Int Suppl40 :S120– S127,1993
9. Van Biesen W, Wiedemann M, Lameire N: End-stage renal disease treatment: A European perspective. J Am Soc Nephrol9[Suppl] :S55– S62,1998
10. Viglino G, Neri L, Alloatti S, Cabiddu G, Cocchi R, Limido A, Marinangeli G, Russo R, Teatini U, Schena FP: Analysis of the factors conditioning the diffusion of peritoneal dialysis in Italy. Nephrol Dial Transplant June 30,2007 [epub ahead of print]
11. Shih YC, Guo A, Just PM, Mujais S: Impact of initial dialysis modality and modality switches on Medicare expenditures of end-stage renal disease patients. Kidney Int68 :319– 329,2005
12. Mendelssohn DC: Empowerment of patient preference in dialysis modality selection. Am J Kidney Dis43 :930– 932,2004
13. Rubin HR, Fink NE, Plantinga LC, Sadler JH, Kliger AS, Powe NR: Patient ratings of dialysis care with peritoneal dialysis vs hemodialysis. JAMA291 :697– 703,2004
14. Prichard SS: Treatment modality selection in 150 consecutive patients starting ESRD therapy. Perit Dial Int16 :69– 72,1996
15. Little J, Irwin A, Marshall T, Rayner H, Smith S: Predicting a patient's choice of dialysis modality: Experience in a United Kingdom renal department. Am J Kidney Dis37 :981– 986,2001
16. Jager KJ, Korevaar JC, Dekker FW, Krediet RT, Boeschoten EW: The effect of contraindications and patient preference on dialysis modality selection in ESRD patients in the Netherlands. Am J Kidney Dis43 :891– 899,2004
17. Mehrotra R, Marsh D, Vonesh E, Peters V, Nissenson A: Patient education and access of ESRD patients to renal replacement therapies beyond in-center hemodialysis. Kidney Int68 :378– 390,2005
18. Mehrotra R: Peritoneal dialysis penetration in the United States: March toward the fringes? Perit Dial Int26 :419– 422,2006
19. Mehrotra R, Blake P, Berman N, Nolph KD: An analysis of dialysis training in the United States and Canada. Am J Kidney Dis40 :152– 160,2002
20. Thamer M, Hwang W, Fink NE, Sadler JH, Wills S, Levin N, Bass EB, Levey AS, Brookmeyer R, Powe NR: US nephrologists’ recommendation of dialysis modality: Results of a national survey. Am J Kidney Dis36 :1155– 1165,2000
21. Furth SL, Hwang W, Yang C, Neu AM, Fivush BA, Powe NR: Relation between pediatric experience and treatment recommendations for children and adolescents with kidney failure. JAMA285 :1027– 1033,2001
22. Excerpts from United States Renal Data System 1997 Annual Data Report. Am J Kidney Dis30 :S1– S213,1997 [published erratum appears in Am J Kidney Dis 30: 732, 1997]
23. O'Hare AM, Johansen KL, Rodriguez RA: Dialysis and kidney transplantation among patients living in rural areas of the United States. Kidney Int69 :343– 349,2006
24. Mehrotra R, Kermah D, Fried L, Kalantar-Zadeh K, Khawar O, Norris K, Nissenson A: Chronic peritoneal dialysis in the United States: Improving outcomes but declining utilization. J Am Soc Nephrol18 :2781– 2788,2007
25. Korevaar JC, Feith GW, Dekker FW, van Manen JG, Boeschoten EW, Bossuyt PM, Krediet RT: Effect of starting with hemodialysis compared with peritoneal dialysis in patients new on dialysis treatment: A randomized controlled trial. Kidney Int64 :2222– 2228,2003
26. Maiorca R, Cancarini GC: Outcome with peritoneal dialysis compared to hemodialysis. In: Textbook of Peritoneal Dialysis, 2nd Ed., edited by Gokal R, Khanna R, Krediet RT, Nolph KD, Dordrecht, Kluwer Academic Publishers,2000 , pp755– 784
27. Bloembergen WE, Port FK, Mauger EA, Wolfe RA: A comparison of mortality between patients treated with hemodialysis and peritoneal dialysis. J Am Soc Nephrol6 :177– 183,1995
28. Fenton SS, Schaubel DE, Desmeules M, Morrison HI, Mao Y, Copleston P, Jeffery JR, Kjellstrand CM: Hemodialysis versus peritoneal dialysis: A comparison of adjusted mortality rates. Am J Kidney Dis30 :334– 342,1997
29. Vonesh EF, Moran J: Mortality in end-stage renal disease: A reassessment of differences between patients treated with hemodialysis and peritoneal dialysis. J Am Soc Nephrol10 :354– 365,1999
30. Held PJ, Port FK, Turenne MN, Gaylin DS, Hamburger RJ, Wolfe RA: Continuous ambulatory peritoneal dialysis and hemodialysis: Comparison of patient mortality with adjustment for comorbid conditions. Kidney Int45 :1163– 1169,1994
31. Murphy SW, Foley RN, Barrett BJ, Kent GM, Morgan J, Barre[Combining Acute Accent] P, Campbell P, Fine A, Goldstein MB, Handa SP, Jindal KK, Levin A, Mandin H, Muirhead N, Richardson RM, Parfrey PS: Comparative mortality of hemodialysis and peritoneal dialysis in Canada. Kidney Int57 :1720– 1726,2000
32. Collins AJ, Hao W, Xia H, Ebben JP, Everson SE, Constantini EG, Ma JZ: Mortality risks of peritoneal dialysis and hemodialysis. Am J Kidney Dis34 :1065– 1074,1999
33. Vonesh EF, Snyder JJ, Foley RN, Collins AJ: The differential impact of risk factors on mortality in hemodialysis and peritoneal dialysis. Kidney Int66 :2389– 2401,2004
34. Jaar BG, Coresh J, Plantinga LC, Fink NE, Klag MJ, Levey AS, Levin NW, Sadler JH, Kliger A, Powe NR: Comparing the risk for death with peritoneal dialysis and hemodialysis in a national cohort of patients with chronic kidney disease. Ann Intern Med143 :174– 183,2005
35. Heaf JG, Lokkegaard H, Madsen M: Initial survival advantage of peritoneal dialysis relative to haemodialysis. Nephrol Dial Transplant17 :112– 117,2002
36. Termorshuizen F, Korevaar JC, Dekker FW, Van Manen JG, Boeschoten EW, Krediet RT: Hemodialysis and peritoneal dialysis: Comparison of adjusted mortality rates according to the duration of dialysis—Analysis of the Netherlands Cooperative Study on the Adequacy of Dialysis 2. J Am Soc Nephrol14 :2851– 2860,2003
37. Liem YS, Wong JB, Hunink MG, de Charro FT, Winkelmayer WC: Comparison of hemodialysis and peritoneal dialysis survival in the Netherlands. Kidney Int71 :153– 158,2007
38. Piraino B, Bargman J: Does the risk of death differ between peritoneal dialysis and hemodialysis patients? Nat Clin Pract Nephrol2 :128– 129,2006
39. Daly CD, Campbell MK, MacLeod AM, Cody DJ, Vale LD, Grant AM, Donaldson C, Wallace SA, Lawrence PD, Khan IH: Do the Y-set and double-bag systems reduce the incidence of CAPD peritonitis? A systematic review of randomized controlled trials. Nephrol Dial Transplant16 :341– 347,2001
40. Mehrotra R, Marwaha T, Berman N, Mason G, Appell M, Kopple JD: Reducing peritonitis rates in a peritoneal dialysis program of indigent ethnic minorities. Perit Dial Int23 :83– 85,2003
41. Maiorca R, Brunori G, Zubani R, Cancarini GC, Manili L, Camerini C, Movilli E, Pola A, d'Avolio G, Gelatti U: Predictive value of dialysis adequacy and nutritional indices for mortality and morbidity in CAPD and HD patients: A longitudinal study. Nephrol Dial Transplant10 :2295– 2305,1995
42. Davies SJ, Phillips L, Russell GI: Peritoneal solute transport predicts survival on CAPD independently of residual renal function. Nephrol Dial Transplant13 :962– 968,1998
43. Diaz-Buxo JA, Lowrie EG, Lew NL, Zhang SM, Zhu X, Lazarus JM: Associates of mortality among peritoneal dialysis patients with special reference to peritoneal transport rates and solute clearance. Am J Kidney Dis33 :523– 534,1999
44. Jager KJ, Merkus MP, Dekker FW, Boeschoten EW, Tijssen JG, Stevens P, Bos WJ, Krediet RT, NECOSAD Study Group: Mortality and technique failure in patients starting chronic peritoneal dialysis: Results of the Netherlands Cooperative Study on the Adequacy of Dialysis. Kidney Int55 :1476– 1485,1999
45. Szeto CC, Wong TY, Leung CB, Wang AY, Law MC, Lui SF, Li PK: Importance of dialysis adequacy in mortality and morbidity of Chinese CAPD patients. Kidney Int58 :400– 407,2000
46. Rocco M, Soucie JM, Pastan S, McClellan WM: Peritoneal dialysis adequacy and risk of death. Kidney Int58 :446– 457,2000
47. Bargman JM, Thorpe KE, Churchill DN: Relative contribution of residual renal function and peritoneal clearance to adequacy of dialysis: A reanalysis of the CANUSA study. J Am Soc Nephrol12 :2158– 2162,2001
48. Shemin D, Bostom AG, Laliberty P, Dworkin LD: Residual renal function and mortality risk in hemodialysis patients. Am J Kidney Dis38 :85– 90,2001
49. Termorshuizen F, Dekker FW, van Manen JG, Korevaar JC, Boeschoten EW, Krediet RT: Relative contribution of residual renal function and different measures of adequacy to survival in hemodialysis patients: An analysis of the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD)-2. J Am Soc Nephrol15 :1061– 1070,2004
50. Rottembourg J, Issad B, Gallego JL, Degoulet P, Aime F, Gueffaf B, Legrain M: Evolution of residual renal function in patients undergoing maintenance haemodialysis or continuous ambulatory peritoneal dialysis. Proc Eur Dial Transplant Assoc19 :397– 403,1983
51. Cancarini GC, Brunori G, Camerini C, Brasa S, Manili L, Maiorca R: Renal function recovery and maintenance of residual diuresis in CAPD and hemodialysis. Perti Dial Bull7 :77– 79,1986
52. Lysaght MJ, Vonesh EF, Gotch F, Ibels L, Keen M, Lindholm B, Nolph KD, Pollock CA, Prowant B, Farrell PC: The influence of dialysis treatment modality on the decline of remaining renal function. ASAIO Trans37 :598– 604,1991
53. Misra M, Vonesh E, Vanstone J, Moore HL, Prowant B, Nolph KD: Effect of cause and time of dropout on residual GFR: A comparative analysis of the decline of GFR on dialysis. Kidney Int59 :754– 763,2001
54. Lang SM, Bergner A, Topfer M, Schiffl H: Preservation of residual renal function in dialysis patients: Effects of dialysis-technique-related factors. Perit Dial Int21 :52– 57,2001
55. Jansen MA, Hart AA, Korevaar JC, Dekker FW, Boeschoten EW, Krediet RT: Predictors of the rate of decline of residual renal function in incident dialysis patients. Kidney Int62 :1046– 1053,2002
56. McKane W, Chandna SM, Tattersall JE, Greenwood RN, Farrington K: Identical decline of residual renal function in high-flux biocompatible hemodialysis and CAPD. Kidney Int61 :256– 265,2002
57. Centers for Medicare and Medicaid Services, Kinney R: 2005 Annual Report: End Stage Renal Disease Clinical Performance Measures Project. Am J Kidney Dis48[Suppl 2] :S1– S106,2006
58. Ishani A, Collins AJ, Herzog CA, Foley RN: Septicemia, access and cardiovascular disease in dialysis patients: The USRDS Wave 2 study. Kidney Int68 :311– 318,2005
59. Aslam N, Bernardini J, Fried L, Burr R, Piraino B: Comparison of infectious complications between incident hemodialysis and peritoneal dialysis patients. Clin J Am Soc Nephrol1 :1226– 1233,2006
60. Plum J, Schoenicke G, Kleophas W, Kulas W, Steffens F, Azem A, Grabensee B: Comparison of body fluid distribution between chronic haemodialysis and peritoneal dialysis patients as assessed by biophysical and biochemical methods. Nephrol Dial Transplant16 :2378– 2385,2001
61. Konings CJ, Kooman JP, Schonck M, Struijk DG, Gladziwa U, Hoorntje SJ, van der Wall Bake AW, van der Sande FM, Leunissen KM: Fluid status in CAPD patients is related to peritoneal transport and residual renal function: Evidence from a longitudinal study. Nephrol Dial Transplant18 :797– 803,2003
62. Davies SJ: Longitudinal relationship between solute transport and ultrafiltration capacity in peritoneal dialysis patients. Kidney Int66 :2437– 2445,2004
63. Ates K, Nergizoglu G, Keven K, Sen A, Kutlay S, Erturk S, Duman N, Karatan O, Ertug AE: Effect of fluid and sodium removal on mortality in peritoneal dialysis patients. Kidney Int60 :767– 776,2001
64. Brown EA, Davies SJ, Rutherford P, Meeus F, Borras M, Riegel W, Divino Filho JC, Vonesh E, van Bree M, on behalf of the EAPOS Group: Survival of functionally anuric patients on automated peritoneal dialysis: The European APD Outcome Study. J Am Soc Nephrol14 :2948– 2957,2003
65. Jansen MA, Termorshuizen F, Korevaar JC, Dekker FW, Boeschoten E, Krediet RT: Predictors of survival in anuric peritoneal dialysis patients. Kidney Int68 :1199– 1205,2005
66. Johnson DW, Armstrong K, Campbell SB, Mudge DW, Hawley CM, Coombes JS, Prins JP, Isbel NM: Metabolic syndrome in severe chronic kidney disease: Prevalence, predictors, prognostic significance and effects of risk factor modification. Nephrology (Carlton)12 :391– 398,2007
67. Williams JD, Topley N, Craig KJ, Mackenzie RK, Pischetsrieder M, Lage C, Passlick-Deetjen J: The Euro-Balance Trial: The effect of a new biocompatible peritoneal dialysis fluid (balance) on the peritoneal membrane. Kidney Int66 :408– 418,2004
68. Lee HY, Park HC, Seo BJ, Do JY, Yun SR, Song HY, Kim YH, Kim YL, Kim DJ, Kim YS, Ahn C, Kim MJ, Shin SK: Superior patient survival for continuous ambulatory peritoneal dialysis patients treated with a peritoneal dialysis fluid with neutral pH and low glucose degradation product concentration (Balance). Perit Dial Int25 :248– 255,2005
69. Brown F, Johnson DW: A randomized controlled trial to determine whether treatment with at neutral pH, low glucose degradation product dialysate (balance) prolongs residual renal function in peritoneal dialysis patients. Perit Dial Int26 :112– 113, author reply 114,2006
70. Kalantar-Zadeh K, Block G, Humphreys MH, Kopple JD: Reverse epidemiology of cardiovascular risk factors in maintenance dialysis patients. Kidney Int63 :793– 808,2003
71. Liu Y, Coresh J, Eustace JA, Longenecker JC, Jaar B, Fink NE, Tracy RP, Powe NR, Klag MJ: Association between cholesterol level and mortality in dialysis patients: Role of inflammation and malnutrition. JAMA291 :451– 459,2004
72. Wanner C, Krane V, Marz W, Olschewski M, Mann JF, Ruf G, Ritz E: Atorvastatin in patients with type 2 diabetes mellitus undergoing hemodialysis. N Engl J Med353 :238– 248,2005
73. Cice G, Ferrara L, D'Andrea A, D'Isa S, Di Benedetto A, Cittadini A, Russo PE, Golino P, Calabro R: Carvedilol increases two-year survival in dialysis patients with dilated cardiomyopathy: A prospective, placebo-controlled trial. J Am Coll Cardiol41 :1438– 1444,2003
74. Kalantar-Zadeh K, Abbott KC, Salahudeen AK, Kilpatrick RD, Horwich TB: Survival advantages of obesity in dialysis patients. Am J Clin Nutr81 :543– 554,2005
75. Abbott KC, Oliver DK, Hurst FP, Das NP, Gao SW, Perkins RP: Body mass index and peritoneal dialysis: “Exceptions to the exception” in reverse epidemiology? Semin Dial2007 , in press
76. Degoulet P, Legrain M, Reach I, Aime F, Devries C, Rojas P, Jacobs C: Mortality risk factors in patients treated by chronic hemodialysis: Report of the Diaphane collaborative study. Nephron31 :103– 110,1982
77. Leavey SF, Strawderman RL, Jones CA, Port FK, Held PJ: Simple nutritional indicators as independent predictors of mortality in hemodialysis patients. Am J Kidney Dis31 :997– 1006,1998
78. Fleischmann E, Teal N, Dudley J, May W, Bower JD, Salahudeen AK: Influence of excess weight on mortality and hospital stay in 1346 hemodialysis patients. Kidney Int55 :1560– 1567,1999
79. Kopple JD, Zhu X, Lew NL, Lowrie EG: Body weight-for-height relationships predict mortality in maintenance hemodialysis patients. Kidney Int56 :1136– 1148,1999
80. Wolfe RA, Ashby VB, Daugirdas JT, Agodoa LY, Jones CA, Port FK: Body size, dose of hemodialysis, and mortality. Am J Kidney Dis35 :80– 88,2000
81. Leavey SF, McCullough K, Hecking E, Goodkin D, Port FK, Young EW: Body mass index and mortality in ‘healthier’ as compared with ‘sicker’ haemodialysis patients: Results from the Dialysis Outcomes and Practice Patterns Study (DOPPS). Nephrol Dial Transplant16 :2386– 2394,2001
82. Port FK, Ashby VB, Dhingra RK, Roys EC, Wolfe RA: Dialysis dose and body mass index are strongly associated with survival in hemodialysis patients. J Am Soc Nephrol13 :1061– 1066,2002
83. Lowrie EG, Li Z, Ofsthun N, Lazarus JM: Body size, dialysis dose and death risk relationships among hemodialysis patients. Kidney Int62 :1891– 1897,2002
84. Glanton CW, Hypolite IO, Hshieh PB, Agodoa LY, Yuan CM, Abbott KC: Factors associated with improved short term survival in obese end stage renal disease patients. Ann Epidemiol13 :136– 143,2003
85. Abbott KC, Glanton CW, Trespalacios FC, Oliver DK, Ortiz MI, Agodoa LY, Cruess DF, Kimmel PL: Body mass index, dialysis modality, and survival: Analysis of the United States Renal Data System Dialysis Morbidity and Mortality Wave II Study. Kidney Int65 :597– 605,2004
86. Stack AG, Murthy BV, Molony DA: Survival differences between peritoneal dialysis and hemodialysis among “large” ESRD patients in the United States. Kidney Int65 :2398– 2408,2004
87. Johansen KL, Young B, Kaysen GA, Chertow GM: Association of body size with outcomes among patients beginning dialysis. Am J Clin Nutr80 :324– 332,2004
88. Kalantar-Zadeh K, Kopple JD, Kilpatrick RD, McAllister CJ, Shinaberger CS, Gjertson DW, Greenland S: Association of morbid obesity and weight change over time with cardiovascular survival in hemodialysis population. Am J Kidney Dis46 :489– 500,2005
89. Johnson DW, Herzig KA, Purdie DM, Chang W, Brown AM, Rigby RJ, Campbell SB, Nicol DL, Hawley CM: Is obesity a favorable prognostic factor in peritoneal dialysis patients? Perit Dial Int20 :715– 721,2000
90. Aslam N, Bernardini J, Fried L, Piraino B: Large body mass index does not predict short-term survival in peritoneal dialysis patients. Perit Dial Int22 :191– 196,2002
91. 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 Nephrol14 :2894– 2901,2003
92. Snyder JJ, Foley RN, Gilbertson DT, Vonesh EF, Collins AJ: Body size and outcomes on peritoneal dialysis in the United States. Kidney Int64 :1838– 1844,2003
93. Li P, Chow KM, Wong TY, Leung CB, Szeto CC: Effects of an angiotensin-converting enzyme inhibitor on residual renal function in patients receiving peritoneal dialysis: A randomized, controlled study. Ann Intern Med139 :105– 112,2003
94. Suzuki H, Kanno Y, Sugahara S, Okada H, Nakamoto H: Effects of an angiotensin II receptor blocker, valsartan, on residual renal function in patients on CAPD. Am J Kidney Dis43 :1056– 1064,2004