Peritoneal dialysis (PD) as the initial treatment modality (Figure 1) seems appropriate for many reasons: quotidian dialysis, preservation of residual renal function, preservation of vascular accesses, convenience of home therapy, flexible times to treatment, and greater feeling of freedom [26];[27].

In addition, peritoneal dialysis easily allows for patient-tailored prescription and incremental dialysis - incremental peritoneal dialysis has several documented benefits, including preservation of residual renal function, reduced risk of peritonitis, less exposure to glucose, greater environmental protection, and reduced costs [28].

Outcomes related to quality of life are discrepant between studies [29];[30]; a recent systematic review and meta-analysis showed that patients treated with PD had better generic, health-related quality of life measured by 36-Item Short Form Health Survey and EuroQoL-5-dimension than hemodialysis patients [31].

Survival on dialysis is still one of the most important considerations and some authors showed a better survival of PD patients compared to hemodialysis (HD) patients during the first 2 years of dialysis treatment [26]; this benefit of early survival in peritoneal dialysis patients compared to HD patients has been confirmed and discussed in recent a revision [32].

The percentage of patients who are transferred from peritoneal dialysis to hemodialysis in the first year remains high in most studies [33]. This should not be a factor against the «PD first» but it forces reflection on the admissibility criteria of these patients and on the risk-benefit balance. Recently, the Australia and New Zealand registry (ANZDATA) identified some factors associated with early transfer of patients: prior renal replacement therapy, age over 70, body mass index less than 18.5 kg/m2, diabetes, ischemic heart disease, cerebrovascular disease, peripheral vascular disease, late referral to nephrology, and treatment in a smaller center [6];[34]. Another study confirmed that treatment in an experienced center (more than 20 incident patients per year) appears to be associated with increased success after initiation of the technique [35].

It seems clear that the success of the technique is dependent on multiple factors, not all of them modifiable. Success may involve increased patient motivation in the process of choosing the technique, greater family involvement in the decision, and discussion about assisted dialysis.

The aging of the population is a challenge for nephrologists; assisted peritoneal dialysis can help maintain home dialysis in elderly patients or in patients with other physical, social, or cognitive limitations. This is especially true if there are other important reasons that do not favor the transition: poor hemodialysis tolerance, living in a remote area where transport to the hemodialysis center can be challenging, and the patient’s sustained desire to maintain home dialysis [36].

Assisted peritoneal dialysis allows assistance for the technique by trained professionals, family members or other cohabitants. This technique is already available in many countries, with regional differences: in France, continuous assisted ambulatory peritoneal dialysis is predominantly used unlike in Canada, where the automated peritoneal dialysis is the most used [36].

Data from France and Denmark suggest that the cost of assisted dialysis is similar to in-center hemodialysis [37];[38] but actually, in the United States of America and Portugal there is no framework for paying for assisted dialysis caregivers.

A recent study showed the feasibility of providing assisted PD by using externally contracted caregivers, with minimization of costs compared to the transition to in-center hemodialysis which constitutes a good argument from the point of view of public funding [39].

The available data indicate that assisted peritoneal dialysis is equally safe. Data from the French Language Peritoneal Dialysis Registry show that the risk of peritonitis was reduced in elderly patients with nursing care [40], and a recent study showed that satisfaction with treatment is higher in assisted PD (compared to in-center hemodialysis) [41].

The authors argue that peritoneal dialysis should be preferred as the first technique, especially in patients with a possible long course of renal disease. Assisted peritoneal dialysis is a clear alternative to the patient who loses autonomy (in a transitory or definitive way) (Figure 1). Efforts should be made to formalize paid caregivers in countries where this reality does not exist.

The possibility of keeping the patient in the preferred modality, when feasible, should be a quality parameter for service providers.

After exhausting the potential of peritoneal dialysis in patient who wants to maintain home dialysis the ideal solution would be home hemodialysis. Home hemodialysis ( HDD) is slowly becoming more accessible, although it is still non-existent or residual in many countries (namely in Portugal) [42] and PD to HHD transitions are relatively infrequent (between 5 and 15%, depending on the data) [43];[44]. One identified barrier for offering direct home-to-home transition is that patients often develop significant comorbidities or complications after the first home dialysis modality technique failure, which, in some cases, may limit continuation of home treatment [45].

A certain percentage of transitions to home hemodialysis are from patients who have previously been treated with peritoneal dialysis [46] and this “selection” is not related to worse outcomes in HHD [47]. A recent study showed that patients with previous PD had similar cumulative patient and technique survival on HHD compared to patients without previous PD [42]. Another study showed that patients transferred to HHD after PD technique failure was associated with lower risk of death and higher incidence of transplant than transfer to in-center hemodialysis (although it lacks further validation) [48]. Successful transitions between home modalities have been reported in other case series [49];[50].

The maintenance of home dialysis, with the transition from PD to HHD, has yet another obvious benefit: the possibility of maintaining daily dialysis. Daily or continuous dialysis regimens are more similar to native kidney function and reduce the magnitude of solute removal and fluid oscillations, with an advantage over intermittent regimens [51]. A systematic review shows that the beneficial effect of daily hemodialysis on hypertension and left ventricular hypertrophy appeared to be relatively consistent across studies [52]. Other studies showed the benefit of daily hemodialysis compared to conventional hemodialysis in terms of controlling hyperphosphatemia [53];[54] and reduction in number of antihypertensive drugs [55]. A recent randomized trial with daily dialysis showed benefits in improving quality of life, general health, and recovery time after the dialysis session [56]. Despite the evidence regarding the benefits of daily hemodialysis, generally it was not accepted as a center-based hemodialysis regimen, given the increased costs (namely with transport) and the inconvenience for the management of the units. Keeping the therapy at home solves this problem.

The period of transition between home modalities is challenging, and little has been published about the implementation of a model of transition from a home to a home modality [43];[50]. Some specific aspects such as need for hospitalization, need for a transitional period of in-center hemodialysis (critical point), training time, and specificities related to the creation and maintenance of vascular access require further research. In a recent retrospective study that evaluated the home-to-home transition over 24 years, half of the cohort required a period of hospitalization and, temporarily, in-center hemodialysis [45].

The process of improving education about dialysis and involving the patient and family in treatment is recognized as a pillar for home dialysis. Home hemodialysis is still residual and the lack of a structure for training patients in order to have the capacity for hemodialysis at home is a factor that contributes to this reality, requiring quick responses from hospitals.

In order to respond to this problem, transitional care units (TCU) emerged [57]. The TCU model consist of independent units that allow all modalities of dialysis treatment in the same place. The four pillars of the units are the establishment of a life plan, health education, medical and psychosocial stabilization, and the reinforcement of self-care [58].

The TCU model offers a program structured by dedicated staff, with better professional/patient ratios than a conventional unit and with the capacity to provide educational services and prepare patients for the dialysis journey. These programs include self-management skills, education, and informed decision support, integration of dialysis techniques and skills related to vascular access [57]. These units can be applied in a public model (preferably) or in a conventional model, which will result in gains for the patient’s journey and will encourage home treatments and better transitions (Figure 1). Specificities related to vascular access (discussed below) also apply to this transition.

The incidence of transition from peritoneal dialysis to in-center hemodialysis (ICH) varies worldwide (3-year transfer rates between 25-40%) and the reasons vary by time of transfer: catheter dysfunction is the main early cause (3-6 months); infections and poor adequacy are the main late etiologies [59]. Peritonitis is one of the main causes of transfer from peritoneal dialysis to hemodialysis, and only a small percentage of patients return to peritoneal dialysis after peritonitis requiring removal of the Tenckhoff catheter [33].

Predicting transfer risk is a challenge for the clinical team. Anticipation and attention are key to a timely transfer under the best conditions. In this setting, anticipation is important in several ways:

-mortality after transition to ICH can be as high as 25% if the transition is unplanned [60].

-anticipation allows the timely construction of a vascular access, avoiding urgent transfers with a central venous catheter (associated with worse short- and long-term outcomes) [61];[62].

-anticipation allows the patient to adapt to the new reality, avoiding sudden and unexpected transitions, reducing the anguish and feeling of autonomy loss. In addition, it allows early action to be taken to reduce the need for transfer between modalities.

The assessment of mortality in the transition between peritoneal dialysis and hemodialysis has not been described using large populations. An American prospective study showed similar mortality between patients on peritoneal dialysis and those who transitioned to in-center hemodialysis [33]. The reason for transfer also contributes to post-transfer mortality: one study showed that patients with mechanical complications had a lower risk of mortality after transition compared to patients who transitioned due to infectious complications [63].

The prognosis is determined by how the transition occurs; timely planning and construction of an autologous access is essential for a smooth transition. However, the moment of construction of the access is difficult to determine and the coordination with the surgical team is not fast in all places. The construction of a preventive vascular access in all peritoneal dialysis patients is not admissible in the light of current knowledge [61];[64];[65].

Some factors have been recognized as associated with the transfer to hemodialysis and with the need for early construction of an autologous access: a Portuguese observational study showed that patients with low Kt/V, low albumin, higher number of hospitalizations and peritonitis represent a high-risk PD population where arteriovenous access should be weighed [66]. However, the individualization of risk depends on many subjective factors, namely related to the physician’s clinical evaluation.

The experience of transition between home hemodialysis and in-center dialysis is residual and there are few data available.