Continuous quality improvement in peritoneal dialysis: Your questions answered

Peritoneal dialysis (PD) uptake around the globe has steadily increased over the last several decades as a viable alternative to haemodialysis. Continued success of this technique for patients is contingent on the application of continuous quality improvement (CQI) principles in PD practice which can improve patient outcomes and in turn lead to more successful PD programmes worldwide. In this installation of 'Your Questions Answered', we will outline an approach to quality improvement initiatives and examine the importance of CQI principles in PD practice. We will also highlight common pitfalls and provide strategies to identify potential targets for improvement within your PD programme.

Obesity, Weight Gain, and Fluid Overload in Peritoneal Dialysis

Obesity is a global epidemic that has a complicated pathogenesis as well as impact on the outcome of peritoneal dialysis (PD) patients. In this review, the prevalence of obesity in incident PD patients as well as the phenomenon of new-onset glucose intolerance after PD will be reviewed. Published literature on the effect of obesity on the survival and incidence of cardiovascular disease in PD patients will be discussed. Particular emphasis would be put on literature that compared the impact of obesity on the outcome of hemodialysis and PD, and the confounding effect of dialysis adequacy. Next, the complex concept of obesity and its relevance for PD will be explored. The focus would be put on the methods of assessment and clinical relevance of central versus general obesity, as well as visceral versus subcutaneous adipose tissue. The relation between obesity and systemic inflammation, as well as the biological role of several selected adipokines will be reviewed. The confounding effects of metabolic syndrome and insulin resistance will be discussed, followed by the prevalence and prognostic impact of weight gain during the first few years of PD. The differences between weight gain due to fluid overload and accumulation of adipose tissue will be discussed, followed by the current literature on the change in body composition after patients are put on chronic PD. The methods of body composition will be reviewed, and the clinical relevance of individual body component (fluid, fat, muscle, and bone) will be discussed. The review will conclude by highlighting current gaps of knowledge and further research directions in this area.

Therapeutic Options for Preservation of Residual Renal Function in Patients on Peritoneal Dialysis

Dialysis is not the ideal renal replacement therapy because it does not fully restore all kidney functions. Increasing evidence suggests that preservation of residual renal function is associated with a survival benefit, a decrease in morbidity, better nutrition, a lower level of inflammatory markers, an improved quality of life, and cost savings by obviating the need for more peritoneal dialysis exchanges and possibly by reducing the requirement for antihypertensive agents, phosphate binders, and erythropoietin. In the present article, we review the impact of residual renal function on patient outcomes and the renoprotective strategies available in patients on peritoneal dialysis.

Flexibility in peritoneal dialysis prescription: Impact on technique survival

Background:

Patient burnout is a major cause of technique failure on peritoneal dialysis (PD). Reducing the PD prescription on an individual basis, dependent upon residual kidney function (RKF), may have a role in prolonging time on PD by reducing dialysis burden. This retrospective study aimed to determine the safety and impact of flexible PD prescribing on technique and patient survival.

Methods:

All patients (186) from our centre starting PD from 1st January 2012 to 31st December 2016 were included. Data on dialysis prescription were collected for each patient from the time they had started PD, and dialysis adequacy measured regularly (3–6 monthly) using PD Adequest.

Results:

Median age at start of dialysis was 61 years. Only 49% started on PD 7 days a week and this dropped to 27% at 3 months following the first clearance test. Over 90% achieved creatinine clearance > 50 L/week/1.73 m2 up to 2 years of follow-up, with 87% achieving this standard at 3 years. Patient and technique survival at 1, 2 and 3 years were 91%, 81%, and 72%, and 89%, 87% and 78% respectively. Factors on univariate analysis affecting technique survival included increasing age (HR 0.98, p = 0.04, 95% CI (0.96–0.999)), two or more episodes of PD-associated peritonitis (HR 4.52, p = 0.00, 95% CI (1.87–10.91)) and increasing PD intensity (HR 3.30, p = 0.02, 95% CI (1.22–8.93)). After multivariate adjustment which included baseline kidney function, low PD intensity continued to be associated with better technique survival (HR 0.17, p = 0.03, 95% CI (0.03–0.85)).

Conclusion:

Tailoring the PD prescription to RKF enables days off dialysis while still maintaining recommended levels of small solute clearance. This approach reduces dialysis burden and is associated with higher technique survival.

Are Three Exchanges Suitable for Asian Patients on Peritoneal Dialysis?

Phenomenal growth in continuous ambulatory peritoneal dialysis (CAPD) has occurred in the developing countries of Asia. In many regions in Asia, neither governments nor insurance companies fully cover treatment expenses for dialysis. Hence, patients in developing countries such as India, Bangladesh, Pakistan, and Nepal use just three 2-L exchanges daily. Typical practice in many centers is to do daytime CAPD with a dry night. Most of our Indian patients who are on three exchanges per day showed a Kt/V of 1.67 and 2-year survival rate of 60% with a normalized protein equivalent of nitrogen appearance of 0.73 – 0.80 g/kg daily. Vegetarians had a lower protein consumption rate and lower serum albumin levels. Peritoneal membrane characteristics vary among high, high average, and low average in various regions of Asia. The prevalence of diabetic nephropathy, with its associated comorbid conditions, as a major cause of end-stage renal disease in the Indian subcontinent explains the differences in the CAPD mortality rates between India and various Asian countries. Given the financial constraints in countries in Asia, small-volume dialysis of 6 L daily may be an acceptable compromise in some patient populations with a smaller body size and significant residual renal function; however, dialysis dose should be individualized according to the needs of each patient.

Peritoneal Dialysis Adequacy in Asia—Is Higher Better?

Sufficient data are available to support the contention that renal and peritoneal clearances are not equivalent, and that loss of residual renal function (RRF) cannot be completely compensated by an increase in the exchange volume or frequency of peritoneal dialysis. When RRF is minimal (for example, renal Kt/V is 0.1 – 0.3), increasing the peritoneal Kt/V beyond the “conventional” value recommended by the Dialysis Outcomes Quality Initiative yields little additional clinical benefit. The cut-off peritoneal ( not total) Kt/V is possibly 1.6 – 1.7. However, delivery of peritoneal small-solute clearance below that cut-off level has a major detrimental effect on clinical outcome in CAPD patients with little RRF. Measures to preserve RRF therefore become an important goal in the treatment of CAPD patients. In short, with regard to RRF (renal Kt/V), higher is always better, and we should always try to preserve it. For peritoneal Kt/V, higher is better only up to a certain limit. The importance of aspects of adequate dialysis other than small-solute removal—especially fluid removal, blood pressure control, nutrition, acid–base balance, mineral metabolism, and anemia and lipid control—cannot be sufficiently emphasized.

How to Have a Successful Peritoneal Dialysis Program

The proportion of end-stage renal disease patients on continuous ambulatory peritoneal dialysis (CAPD) has increased by twofold in Hong Kong over last two decades, accounting for 80% of the entire dialysis population. Our encouraging outcome results—a 2-year actuarial patient survival of 83%, and a 2-year technique survival of 72.8%—further testify to the success of CAPD in our territory. A relatively constant successful outcome has been achieved despite an increasing prevalence of diabetes mellitus and an aging population. The present review postulates the reasons behind our success. Apart from reimbursement policy, technique-related factors, and center effects, inherent patient factors—including baseline survival advantage of Chinese patients, genetic difference, cardiovascular risk factors, and possibly lower dialysis volume requirement and compliance—are thought to be contributory. As for the future, more efforts are needed to further improve the technique survival rate and the nutritional status, psychosocial well-being, and rehabilitation of CAPD patients. Judicious assessment of peritoneal dialysis adequacy and preservation of residual renal function should be constantly exercised to tailor treatment to the needs of Chinese CAPD patients.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers for preserving residual kidney function in peritoneal dialysis patients

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEis) and angiotensin receptor blockers (ARBs) are widely used in peritoneal dialysis (PD) patients, yet controversy exists about their impact on residual kidney function.

OBJECTIVES

This review aimed to evaluate the benefits and harms of ACEis and ARBs for preserving residual kidney function in PD patients.

SEARCH METHODS

The Cochrane Renal Group's specialised register, Cochrane Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE (OvidSP interface), Chinese Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI) and other resources were searched by applying a prespecified comprehensive search strategy. Date of last search: 01 May 2014.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing ACEis or ARBs with placebo, other antihypertensive drugs or each other in PD patients were included.

DATA COLLECTION AND ANALYSIS

Screening, selection, data extraction and quality assessments for each retrieved article were carried out by two authors using standardised forms. Authors were contacted when published data were incomplete. Statistical analyses were performed using the random effects model and results expressed as risk ratio (RR) with 95% confidence intervals (CI). Heterogeneity among studies was explored using the Cochran Q statistic and the I² test, subgroup analyses and random effects meta-regression.

MAIN RESULTS

Six open-label studies (257 patients) were identified. One study compared ACEi with other antihypertensive drugs, three compared ARBs with other antihypertensive drugs, and two studies compared an ARB with an ACEi. Long-term use (≥ 12 months) of an ARB showed significantly benefit of preserving residual kidney function in continuous ambulatory PD (CAPD) patients (MD 1.11 mL/min/1.73 m², 95% CI 0.38 to 1.83), although there was no significant benefit when an ARB were used short-term (≤ six months). One study showed that compared with other antihypertensive drugs, long-term use (12 months) of the ACEi ramipril showed a significant reduction in the decline of residual kidney function in patients on CAPD (MD -0.93 mL/min/1.73m², 95% CI -0.75 to -0.11), and delayed the progression to complete anuria (RR 0.64, 95% CI 0.41 to 0.99). There was no significant difference in serum potassium, urinary protein excretion, Kt/V, weekly creatinine clearance and blood pressure for ARBs versus other antihypertensive drugs. Compared with other antihypertensive drugs, ramipril showed no difference in mortality and cardiovascular events. Compared with an ACEi, ARBs did not show any difference in residual kidney function.The selection bias assessment was low in four studies and unclear in two. Five studies were open-label; however the primary outcome (residual kidney function) was obtained objectively from laboratory tests, and were not likely to be influenced by the lack of blinding. Reporting bias was unclear in all six studies.

AUTHORS' CONCLUSIONS

Compared with other antihypertensive drugs, long-term use (≥ 12 months) of ACEis or ARBs showed additional benefits of preserving residual kidney function in CAPD patients. There was no significant difference on residual kidney function preservation between ARBs and ACEis. However, limited by the small number of RCTs enrolling small number of participants, there is currently insufficient evidence to support the use of an ACEi or an ARB as first line antihypertensive therapy in PD patients.

Is there a survival advantage in Asian peritoneal dialysis patients?

Over the last decade, epidemiological surveys and qualitative research literature have demonstrated and validated a better survival in the Asian peritoneal dialysis population. This review summarizes the current understanding of Asian peritoneal dialysis patient survival and attempts to scrutinize the supposed survival advantage of this population group. We outlined the published peritoneal dialysis survival data from a literature search, with reference to dialysis patient cohorts from 1983 through 2002 for prevalent cases and 1980 through 2002 for incident patients. Two-year and 5-year patient survival rates in excess of 80% and 60% respectively were demonstrated in Asian countries, which compared favorably with the CANUSA, ADEMEX and most Caucasian series. Better end-stage renal disease patient survival is apparent despite a dialysis adequacy disadvantage, for reasons yet to be identified. As is the case of other racial disparities in medical care, such a difference is a product of more than biological differences and include budgetary barrier, health care system and geographic variation, physician bias and statistical pitfalls. Particular efforts should therefore be made to explore the underlying reason(s) for the Asian peritoneal dialysis patient survival advantage. Alternative approach and guidelines to peritoneal dialysis delivery in Asia might be warranted.