Quality of Life and Mortality in Peritoneal Dialysis

Quality of life

The various domains of life are affected when any type of renal replacement therapy is initiated. Dialysis treatments are associated with several limitations, including time commitment, symptoms associated with treatment, and dietary restrictions. These factors, coupled with other social changes, including loss of occupation and hobbies, can significantly affect the quality of life of patients with kidney failure (2).

The Centers for Medicare & Medicaid Services has mandated that health-related quality of life (HrQoL) assessments must be made annually. With significant operational differences between PD and hemodialysis (HD), multiple studies have attempted to evaluate whether HrQoL scores vary on the basis of modality. A 2018 systematic review and meta-analysis of 15 studies with a pooled sample size of 4318 patients found no difference in physical, psychologic, or general domains between the modalities (3). Furthermore, that study evaluated the advancements in both modalities over time. Studies published before 2006 showed no difference in modality, whereas studies published after 2006 showed PD to benefit quality of life. Recently, Eneanya et al. (4) sought to evaluate longitudinal trends in HrQoL using a Fresenius database. Their study compared 880 home modality patients with 4234 in-center patients. The results showed that in-center patients had a significantly lower mean HrQoL at baseline, but irrespective of dialysis type, there was no change of HrQoL in patients who continued to use the same modality. Interestingly, patients who switched from home dialysis to in-center dialysis were found to have a decrease in physical functioning.

Morbidity

Complications specific to PD fall into two major categories: issues with dialysis treatment and complications related to PD. Issues with dialysis treatment include flow dysfunction, infusion pain, drain pain, leak, and ultrafiltration failure. Whereas these obstacles may occur at any time during treatment, physicians must be vigilant and troubleshoot for them as soon as symptoms occur. Complications related to PD include peritonitis, exit site infection, hydrothorax, chyloperitoneum, and encapsulating peritoneal sclerosis. Conversations about morbidity should be included in discussions of PD as a potential modality. The morbidity of PD will be discussed in more detail in a future ASN Kidney News article.

Mortality

When examining the association of PD with mortality, nephrologists rely on several observational studies because there are no successful randomized controlled trials. One randomized controlled trial in the Netherlands was attempted in 2003 but was limited for enrollment and therefore underpowered (5). Some of these observational studies examining mortality have often compared PD with HD because researchers have long questioned whether either modality provides a slight advantage over the other.

The United States Renal Data System (USRDS), which collects, analyzes, and distributes information on ESRD patients, found that the adjusted mortality rates in 2016 for HD patients and PD patients were 166 and 154, respectively, per 1000 patient-years (6). This finding added to the perception that there is a clinically significant difference in mortality among dialysis modalities.

A review of the trend over time shows an improvement in unadjusted mortality in PD patients; in those starting peritoneal dialysis in 2003, the 5-year survival was only 42.9%, whereas in those starting PD in 2011, the 5-year survival was 52.1%. Unfortunately, comparing PD and HD patients at face value is problematic. The heterogeneity of PD and HD patients is a major limitation in these studies because PD patients are on average younger, healthier, and more likely to have cystic or glomerular disease, according to the USRDS (6). Wong et al. (7) attempted to control for this by using a standardized assessment of outcomes in patients eligible for both modalities as determined by a multidisciplinary team. They found that among all incident kidney failure patients, PD was associated with a lower risk of death in those <65 years of age. Interestingly, when excluding patients ineligible for PD, they also found that some who were eligible for both modalities had a similar mortality risk that did not vary over time.

With conflicting study results, researchers sought to examine whether perhaps survival benefit changed over time. A large analysis by Yeates et al. (8) compared incident PD and HD patients from 1991 to 2004 from the Canadian Organ Replacement Registry. The results from that study also showed variability in survival, with a favorable risk in PD patients for the first 18 months followed by a favorable risk in HD patients after 36 months. A subgroup analysis between 2001 and 2004 showed that PD was superior for the first 24 months; afterward, both modalities had similar outcomes. That study reaffirms the variations in survival over time and highlights the early benefit for PD patients. Later, Kumar et al. (9) compared the outcomes in matched incident PD and HD patients in the Kaiser Permanente registry. Excluding patients who received dialysis through a central venous catheter during the first 90 days of dialysis, they found that the cumulative risk of death favored PD for the first 3 years, with no difference after that time. This finding led to some clinicians advocating for a transitional kidney failure plan with PD as the primary modality and transition to home HD when residual kidney function is lost (10). However, whereas studies attempt to control heterogenicity among HD and PD patients, it is likely that some residual confounding variables remain. It is difficult to provide an overarching recommendation, especially given the number of conflicting studies.

In conclusion, a true luminary in the field of home dialysis, Joanne Bargman, MD (11), helps capture the essence of this topic with the following statement: “In light of the recent emphasis on patient-centered outcomes and quality of life for patients with kidney disease, we contend that the nephrology community should no longer fund, perform, or publish studies that compare survival by dialysis modality. These studies have become redundant; they are methodologically limited, unhelpful in practice, and therefore a waste of resources.”

Conclusion

Several attempts have been made to compare quality of life and patient survival as associated with dialysis modalities. A large meta-analysis spanning >17 years found no difference in HrQoL between dialysis types; however, a recent longitudinal study found decreased scores when patients switched from home to in-center dialysis (3). With no randomized controlled trials and with limited and conflicting observational data, mortality differences between dialysis modalities likely vary over time and should not affect conversations about selecting a dialysis modality. It is important for clinicians to understand and convey findings on the quality of life, morbidity, and mortality associated with each type of dialysis. Discussing these topics with patients can strengthen the provider–patient bond and also help determine the best dialysis modality for each patient.