In-center HD or home HD
PD
CHD (mainly in-center)
SDHD
NHD
CAPD
APD
Location
At a hospital/satellite dialysis unit
At a hospital/satellite dialysis unit or home
At a hospital/satellite dialysis unit or home
Home or work, but any clean place possible
Home, but any clean place possible
Typical number of session per week
3
5–7
5–7
Every day
Every day
Typical number of session per day
1
1
1
4–5
1
Typical length of sessions (hours)
4
1.5–3
6–8 (modifiable as prescription)
4–6 (modifiable as prescription)
8–10 (modifiable as prescription)
Operating person
Staff at a hospital
Staff at a hospital or trained patient/family
Staff at a hospital or trained patient/family
Trained patient or family member
Trained patient or family member
Necessity
A traditional dialysis machine and dialysate
A traditional dialysis machine and dialysate or portable dialysis machine
A traditional dialysis machine and dialysate or portable dialysis machine
Dialysis fluid
A machine and dialysis fluid
Access
Any vascular access (catheter, AVF, or AVG)
Any vascular access (catheter, AVF, or AVG)
Any vascular access (catheter, AVF, or AVG)
Peritoneal catheter
Peritoneal catheter
HD and PD have different profiles of advantages or disadvantages (Table 2.2). HD depends on machines to remove uremic toxins and fluid and has a higher efficiency profile than that of PD. Because creating vascular access is essential for HD, this modality may not be useful for patients with severe atherosclerosis or poor vascular condition. In addition, anticoagulation therapy is needed during the extracorporeal circulation in dialysis, and patients may experience uncontrolled bleeding . For in-center HD, patients or family members do not need to participate in the delivery of HD, so it is appropriate for patients who are dependent on physicians or those lacking a support system. However, transportation to a hospital or HD center is needed for in-center HD. In addition, it is easier to monitor adherence with treatment, for example, injection of parenteral erythropoietin. However, the schedules are usually inflexible, and traveling to the place of dialysis is sometimes difficult. Some patients receiving in-center HD suffer from post-dialysis fatigue and exhaustion and feel difficulties in working on HD days. Moreover, myocardial stunning occurs during dialysis with aggressive ultrafiltration (Nie et al. 2016). In contrast, vascular access or anticoagulation therapy is not needed with PD, and the “lost time” to starting dialysis after catheter placement is less compared to that for HD, for which needs several weeks of maturation time for vascular access . PD has a lower risk of bacteremia due to its characters of “needleless,” and PD has a better hemodynamic stability. PD usually preserves residual renal function better than HD does, and it can be used as a bridge to transplantation (Moist et al. 2000; Sezer et al. 2011). In addition, PD is originally a “home therapy” and provides more flexible schedules and more independence. Therefore, PD is more attractive for patients who want to keep working or studying or for those who have children at home. However, the efficacy of PD for removing uremic toxins and fluids is lower than that of HD, especially in patients with large body size or lower peritoneal membrane transport characteristics. In addition, it is not possible to precisely predict the peritoneal ultrafiltration volume in PD. Further, the clinical challenges of PD include complications such as peritonitis, catheter-related mechanical complications, and metabolic complications such as weight gain, hyperglycemia, hyperinsulinemia, and hypertriglyceridemia. Lastly, patients on PD have no “off days,” which can be exhausting for both patients and family members.
Table 2.2
Advantages and disadvantages of hemodialysis and peritoneal dialysis
Advantages | Disadvantages | |
|---|---|---|
Hemodialysisa | Higher efficiency in uremic toxin and fluid removal | Dependent on the machine |
Anticoagulation and increased risk of bleeding | ||
Better monitoring of adherence with treatments | ||
Inflexible schedules | ||
Transportation to a dialysis center | ||
Post-dialysis fatigue or exhaustion | ||
Peritoneal dialysis | No vascular access | Lower efficiency in uremic toxin and fluid removalb |
No anticoagulation | ||
Difficult prediction of precise ultrafiltration volume | ||
Better hemodynamic stability | ||
Flexible schedules | ||
Metabolic complication of glucose-based peritoneal fluid | ||
Better preservation of residual renal function | ||
Exhaustion due to no “off-day” | ||
More independence | Room for supplies |
2.2.2 Comparison of Survival Outcomes by Dialysis Modality
While selecting a dialysis modality, patients want to determine the most ideal or appropriate options for RRT that could enhance their survival by quantity as well as quality. Since current data on the survival of dialysis patients are limited by study design or heterogeneity, it is not easy for individual patients to make a scientific decision on the basis of the survival outcomes reported in the literatures (Choi et al. 2013a).
Randomized controlled trials (RCTs) are the most ideal study design to compare clinical outcomes by dialysis modality. However, in real clinical practice, it is difficult to perform RCTs focusing on modality selection . The one RCT published thus far had to be terminated prematurely because over 90% of eligible patients did not agree to randomization (Korevaar et al. 2003). Educated or informed patients usually have their own preferences regarding dialysis modality, and random allocation that goes against these preferences is a significant challenge to RCTs. Another RCT was completed in China, but the results have not been reported yet (ClinicalTrials.gov identifier: NCT01413074). Because of the many obstacles in RCTs, observational cohort studies were used instead to compare clinical outcomes by dialysis modality. However, the survival data obtained through observational studies have several limitations, including population heterogeneity, selection bias, and discordance in the method of adjustment for various measured or unmeasured confounding factors (Merchant et al. 2015). In observational studies, statistical techniques can be used to adjust for differences in patient characteristics or comorbidity profiles between groups. In particular, the recent application of more sophisticated statistical matching techniques, such as propensity score matching or marginal structural models, has enabled comparison of clinical outcomes by dialysis modality in a more scientific manner with observational studies (Austin 2009; Suarez et al. 2011).
Observational cohort studies using national registry-based data have shown inconsistent results. For example, some studies found no differences in mortality risk between PD and HD by using the US Renal Data System (USRDS) data (20) or Canadian dialysis population data (21), while the study conducted with data from a Danish registry showed consistent survival advantages of PD over HD (Heaf and Wehberg 2014). This discrepancy is partly attributed to selection bias or differences in patient characteristics and/or the degree of adjustments. In addition, whether or not these data exclude data of the first 90 days of dialysis could also affect the results. The survival advantage of PD over HD observed from day 0 data was no longer observed on analysis of data from 90 days after initiation (Quinn et al. 2011), and it has been proposed that acutely ill patients might be disproportionately included to HD in that case. Along the same lines, the initial survival advantage of PD over HD is associated with the higher risk of central venous catheter for HD in the initial period (Perl et al. 2011). The type of vascular access could thus be an important component of the association between modality and survival.
A study using marginal structural model analysis showed that the earlier survival advantage of PD relative to HD for 24 months is independent of known confounders (Lukowsky et al. 2013). Further, a recent analysis of Australia and New Zealand Dialysis and Transplant (ANZDATA) registry data found that the crossover point of survival between PD and HD was nearly 1 year after the initiation of dialysis: up to 1 year from the start of dialysis, PD had a survival advantage over HD, but its mortality risk was higher than that of HD after 1 year (McDonald et al. 2009). From the same registry with dialysis patients on various dialysis modalities including facility HD and home HD and PD, a survival advantage of home HD was observed. In the same report, adjusted mortality of PD overall was significantly higher compared to facility HD, while mortality of PD was significantly lower until 12 months of follow-up (Marshall et al. 2011). A national prospective cohort study in Korea has consistently shown earlier survival advantage of PD over HD (Choi et al. 2013b), but in this case, the survival advantage persists until 42 months after dialysis initiation from day 90 after initiation (Jung et al. 2015).
The survival outcomes from these cohort studies vary by subgroup. Age, presence of diabetes, and comorbidities, particularly cardiovascular disease (CVD), influence the effect of dialysis modality on survival: younger, nondiabetic patients with no additional comorbidities had a lower risk of death with PD than with HD, but older patients with diabetes had a higher risk of death with PD than with HD (Mehrotra et al. 2011; McDonald et al. 2009).
In addition, in a more contemporary cohort, some changes in relative mortality risk were observed between HD and PD (Mehrotra et al. 2011). Data from the USRDS show that the survival trend is similar between patients starting dialysis with PD or HD. A similar result from Canadian cohort has demonstrated that the survival difference between PD and HD was decreased in a recent dialysis cohort using stratified analysis by dialysis initiation period (Yeates et al. 2012). In addition, improvement of outcomes has been founded in subgroup of patients; the attenuated risk of death in the older diabetic patients was compared to the earlier cohorts (Mehrotra et al. 2011; Heaf and Wehberg 2014).
A summary of the outcomes of recent studies comparing survival between HD and PD is presented in Fig. 2.1. Overall, despite the initial survival advantage of PD over HD, the long-term survival rate is similar between these modalities. Therefore, survival rate cannot be used as a parameter in decision-making on dialysis modality selection.
Fig. 2.1
Outcomes of recent studies comparing survival of hemodialysis and peritoneal dialysis patients. HR hazard ratio, CI 95% confidence interval, DM diabetes mellitus, USRDS the US Renal Data System, CORR the Canadian Organ Replacement Register, ANZDATA the Australia and New Zealand Dialysis and Transplant, and CRC for ESRD Clinical Research Center for End Stage Renal Disease *p < 0.05
2.2.3 Comparisons of Other Clinical Outcomes by Dialysis Modalities
CVD is the most common cause of death in dialysis patients, accounting for about 40% of deaths in dialysis patients in Western countries. The association of dialysis modality and cardiovascular mortality or risk has not been clearly evaluated. In an earlier observational study, periodic dialysis in HD is associated with sudden and cardiac death after weekend (Bleyer et al. 1999). In addition, abrupt hemodynamic shifts and the rapid loss of residual renal function in HD may be associated with the increased cardiovascular risk in HD (Moist et al. 2000). On the other hand, repeated glucose exposure and systemic absorption and the subsequent metabolic derangements including insulin resistance, hypertriglyceridemia, and metabolic syndrome in PD also increase CVD risk, although the lower fluctuations in body fluid and electrolyte concentration potentially reduce it (Johnson et al. 2007). Analysis of ANZDATA registry data showed that PD is associated with a higher risk of CVD death than HD (Johnson et al. 2009a). A retrospective matched-pair cohort in the USA showed that HD is associated with better survival among subgroups with cardiovascular disease than PD (Weinhandl et al. 2010). In addition, a nationwide population-based study in Korea showed that the relative risk for major cardiac and cerebrovascular events after dialysis is higher in PD than HD after covariate-adjusted analysis (Kim et al. 2015).
Infection is the second leading cause of death in dialysis patients. The overall infection rates are similar between PD and HD, but studies have shown that cases of serious bloodstream infection are lower in PD than in HD (Saran et al. 2016). However, analysis of ANZDATA registry data showed PD has an increased risk of infection-related death than HD has, and this was mainly related to increased risk for death by bacterial and fungal peritonitis (Johnson et al. 2009b). Additionally, analysis of the Netherlands Cooperative Study on the Adequacy of Dialysis cohort also showed that compared to HD, PD carried a higher overall infection risk attributable to dialysis technique-related infection. However, during the first 6 months, the incidence rate of infection is higher with HD than PD (van Diepen et al. 2014). A Canadian retrospective study showed that PD was associated with a higher risk of infection-related hospitalization than HD (Lafrance et al. 2012), although subsequent analysis of the same group showed that PD is not associated with a higher mortality or all-cause overall readmission after the initial infection-related hospitalization (Laurin et al. 2015).
Generally, there is still paucity of evidence supporting the effect of dialysis modality on CVD outcome or fatal infectious complications, and the differences in CVD- or infection-related mortality between modalities are not usually considered a major determinant in modality selection .
2.3 Factors Influencing Decision-Making in Dialysis Modality Selection
The selection of dialysis modality is affected by many different factors: medical factors include comorbidities , previous abdominal surgery , and patient tolerability to volume shifts, while nonmedical factors include patient preference, their home situation such as family support or self-perceived burden on their family, socioeconomic factors such as accessibility of the dialysis center, financial factors such as the method of reimbursement, and cultural factors (Wauters and Uehlinger 2004).
Medically, HD is contraindicated in cases in which it is difficult to create a vascular access and relatively contraindicated in patients who cannot tolerate volume shifts, whereas PD is contraindicated in cases of peritoneal adhesion, large mesenteric resection, large abdominal hernia, peritoneal defects such as peritoneal-pleural communications, and severe chronic obstructive airway disorders. Regarding comorbidities, patients who select PD have variable degree of comorbidities in different cohorts: less comorbidities have been found in the US, Canadian, and Korean cohorts but higher comorbidities have been found in the Australian and New Zealand cohorts (Mehrotra et al. 2011; Perl et al. 2011; McDonald et al. 2009; Choi et al. 2013b). Because most patients do not have any medical contraindications to HD or PD, they are usually free to choose to either modality.
Patients who choose PD as the initial dialysis modality are usually independent, prefer therapy at home and flexible schedules, have the ability to continue work or traveling while on dialysis, and have the ability to care for their children. However, patients not choosing PD as a dialysis modality have concerns about indwelling catheter in the abdomen, concerns about sterility or fear about getting an infection related to the self-procedure, and concerns about storage space for dialysis supplies (Morton et al. 2010). On the other hand, patients who choose HD as a dialysis modality usually want physicians to take care of them and prefer planned schedules or free day without dialysis and the convenience of HD. On the other hand, patients not choosing HD have needle phobia, fear of cross infection during extracorporeal circulation.
A recent data investigating the influence of behavioral stage of change on dialysis modality decision-making showed that people who have higher dialysis knowledge tended to act rather than just think. In other words, knowledge about dialysis helps patients decide on dialysis modality (Prakash et al. 2015). Figure 2.2 presents a conceptual framework within which patients function while selecting a dialysis modality.
Fig. 2.2
Conceptual model for dialysis decision-making. CKD chronic kidney disease, RRT renal replacement therapy [adapted from Prakash et al. (2015)]
In addition to the patient preference, physician reimbursement incentive, funding policy, and the type of provider also influence the choice of dialysis modality. Reimbursement for dialysis is a major factor involved in the selection process, not only for patients but also for healthcare providers. With the introduction of a capitation fee in the late 1990s, the use of PD reduced continuously in Ontario, Canada (Mendelssohn et al. 2004). However, in recent years, several Asian countries, including Hong Kong, Vietnam, Taiwan, and Thailand, as well as New Zealand and Australia, have introduced reimbursement policies for PD, whereby the use of this modality has increased (Kwong and Li 2015). In addition, US data have shown that the new bundled prospective payment system (PPS) provided a financial incentive for increased use of PD (Hornberger and Hirth 2012), and consequently, under the Medicare bundled PPS, an increasing proportion of patients who are receiving PD and home HD rather than in-center HD are expected to be able to save on dialysis costs (Liu et al. 2014). In fact, the use of PD has increased since the introduction of bundled PPS (Saran et al. 2016). In contrast, without changes in the payment systems, PD use has steadily declined since 2007, as reported in a European observational study based on registry data, despite the initial survival advantages of PD (van de Luijtgaarden et al. 2016). A previous European study also showed that the type of provider, whether public or private, affects PD use (De Vecchi et al. 1999). A similar finding was also reported on the basis of US data, in that, the ownership pattern of the dialysis unit was found to affect PD use in the USA (Mehrotra et al. 2009). Overall, the analysis of the cost and incentive mechanism for low-cost dialysis modality has shown that the proportion of profit dialysis centers is associated with the utilization rate of low-cost dialysis (Cleemput and De Laet 2013).
The cost of ESRD care has increased worldwide, and the annual cost of HD in the USA continues to increase (Saran et al. 2016; Manns et al. 2007), because of the increasing prevalence of ESRD. Therefore, it is vital to understand the cost effectiveness of dialysis treatment in order to ensure appropriate use of resources and provide stable healthcare. Between the two dialysis modalities, PD is usually less expensive and more cost effective than HD, in most countries (Chang et al. 2016; de Wit et al. 1998; Lee et al. 2002). Several studies from Western Europe and North America have shown that healthcare costs for HD are about 30–50% higher than those for PD (Karopadi et al. 2013). However, in developing countries, PD is considered more expensive than HD because of the high-cost supplies and relatively lower cost of labor, but actually, PD is less expensive than HD (Hooi et al. 2005; Lo 2002). Despite these advantages (Neil et al. 2009), PD penetration is still considerably lower than HD penetration, except in some countries; at the end of 2014, only an estimated 11% of dialysis patients were treated with PD globally. Considering the outcome data and feasibility, PD seems to be an underutilized modality (Jiwakanon et al. 2010). Therefore, potential bias that could interfere with the choice of dialysis modality should be prevented at the individual physician level, and structural healthcare policies should be introduced for global equity in provision of both dialysis modalities at national levels.
2.4 Selection of Dialysis Modalities for Special Subgroups
Most patients do not have any contraindications for one dialysis modality over the other. Several studies have shown that most patients are medically eligible for PD (Jager et al. 2004). However, in special subgroups of patients, physicians focus on patient characteristics and consider the specific benefits or risks of HD or PD.
2.4.1 Dialysis in the Elderly
The number of elderly patients who need RRT has recently increased (Saran et al. 2016). Given the reduced life expectancy of many elderly patients and the lack of evidence supporting the usefulness of dialysis in improving life expectancy, it is more difficult to decide whether or not to start dialysis, to find the appropriate time for dialysis initiation, and to select the dialysis modality. Therefore, in these cases, it is very important to discuss dialysis decisions with patients and their families.
In elderly patients, PD is beneficial because of its cardiovascular stability and because patients do not need to travel to and from the dialysis canter. In addition, PD does not require repeated vascular puncture: the veins of some elderly patients are often unsuitable for the repeated puncture required in HD. However, PD is risky for some elderly patients, especially those with impaired vision and decreased mental activity, because these impair the self-performance of the dialysis procedure (Dimkovic and Oreopoulos 2000). In addition, patients of advanced age have decreased manual dexterity, have difficulty in ambulating, are unable to perform exchanges by themselves, and may lack social support, because of which PD tends to be a more difficult option for them. Connection assist-devices or cyclers are alternative solution in such case, and assisted PD is another option (Saran et al. 2016; Segall et al. 2017).
Assisted PD is a type of home-care assistance that can allow more patients to receive PD at home. There are two models of assisted PD: automated PD with two daily nurse visits and automatic PD or CAPD with a home health assistant or family member trained as an assistant, which requires another one visit from a trained nurse. The assisted PD program is cost-saving despite the additional cost for caregivers (Brown et al. 2007; Couchoud et al. 2015a).
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