Underutilization of Peritoneal Dialysis

Considerable progress has been made during the past decade in the practice and theory of peritoneal dialysis for end-stage renal disease (ESRD). One previous major concern was whether peritoneal dialysis could deliver enough clearance to meet targets for adequacy of dialysis. Patients can be divided into low and high peritoneal transport categories depending on measured clearance rates.¹ Anuric "low transporters" were considered at particular risk for underdialysis. However, epidemiological studies showed paradoxically lower morbidity and mortality in this group.² High transporters, while easily achieving conventional dialysis targets, were characterized by ultrafiltration failure (due to rapid loss of glucose, and thereby osmotic pressure, from the dialysis fluid), hypertension, excess peritoneal loss of albumin, and excess mortality.

Two solutions to this problem have been discovered. First, the widespread introduction of automated peritoneal dialysis, whereby dialysis fluid is exchanged frequently while the patient is asleep, improves ultrafiltration and reduces even further the time that the patient needs to devote to dialysis procedures, since daytime exchanges are often not required. Most patients, even those who are anuric,³ are suited to automated peritoneal dialysis. Second, the introduction of icodextrin dialysis fluid, containing a polyglucose that maintains a long-term osmotic pressure gradient, has reduced the problem of negative ultrafiltration during the night exchange or long day exchanges.⁴

On another front, improvements in connector technology and training techniques have reduced peritonitis frequency, such that episodes per patient of less than 1 per 24 months are now the norm.⁵ The introduction of biocompatible peritoneal dialysis fluids has reduced dialysis discomfort and promises further reduction in peritonitis frequency and better long-term preservation of peritoneal function.

Some epidemiological studies have shown an adjusted survival advantage for peritoneal dialysis compared with hemodialysis during the first 2 years of dialysis.^{6 - 7} This may be real, possibly due to better preservation of residual renal function,⁸ or may be an artifact due to differences in patient selection.⁹ However, a recently published randomized controlled trial found a significant survival advantage for patients who received peritoneal dialysis.¹⁰ A reasonable conclusion therefore is that peritoneal dialysis is at least as good an initial therapy as center or satellite hemodialysis for all patient groups, with the possible exception of elderly diabetic patients.¹¹ Home hemodialysis is a special case, but since it requires higher intellectual functioning, more time, greater training requirements, and frequent home assistance, it is infrequently used in most centers since the advent of peritoneal dialysis.

Technique failure rates for peritoneal dialysis at 7% to 11% per year¹² are generally higher than for hemodialysis, either due to patient "burn-out" (reduced motivation due to increasing morbidity), recurrent peritonitis, or peritoneal membrane failure. The "integrated care" approach to ESRD¹³ does not consider this relatively higher failure rate to be a contraindication. This concept advocates that hemodialysis, peritoneal dialysis, and renal transplantation should all be offered to the patient in an unbiased way, and that all 3 modalities may be a part of treatment during the patient's lifetime. For many, peritoneal dialysis will be a reasonable initial choice, hopefully followed by renal transplantation, but otherwise with timely conversion to hemodialysis should complications arise from peritoneal dialysis.

Peritoneal dialysis is an efficient and less expensive dialysis modality that can be tailored to the individual patient's clinical and social requirements. It permits a high degree of social rehabilitation and travel freedom. Given an informed choice, approximately half of patients will choose peritoneal dialysis.^{14 - 15} However, some 20% of patients will a priori be unsuitable for peritoneal dialysis¹⁵ either due to abdominal problems (eg, hernias, multiple operations), physical disabilities (eg, hemiparesis), or psychological problems (eg, dementia, noncompliance), so overall rates of newly initiated peritoneal dialysis cannot be expected to be as high.

In this issue of THE JOURNAL, Rubin et al¹⁶ present findings from their study showing that peritoneal dialysis patients rate their care higher than hemodialysis patients do. After adjusting for case mix, patients receiving peritoneal dialysis were 1.46 times more likely to rate their dialysis care as excellent and 1.2 times more likely to recommend their dialysis center to others as were patients receiving hemodialysis. Ratings were higher for all 23 items investigated, including dialysis dose, clinician caring and concern, availability, information, and technical aspects of care. As the authors point out, these differences may be partly a consequence of the home dialysis setting, rather than peritoneal dialysis per se: a high degree of information and interpersonal contact, at least in the early stages of dialysis (ie, within a mean of 7 months of starting dialysis) studied in this report, is necessary for a home dialysis program to succeed. Despite this caveat, the findings suggest that peritoneal dialysis is an acceptable modality and has a high degree of patient satisfaction, particularly among independent individuals living some distance away from their dialysis center.

Given these findings, it is therefore surprising that the incidence and prevalence of peritoneal dialysis use in the United States continue to decline, reaching 7.5% (6991 new peritoneal dialysis patients/93 280 new dialysis patients) and 8.4% (24 268 peritoneal dialysis patients/288 978 dialysis patients), respectively, in 2001¹⁷ and already are much lower than rates in countries with comparable economies, such as Canada,⁶ the Netherlands, Denmark, and Sweden.¹⁸ It appears that the explanation is not physician preference: US nephrologists believe that 33% of ESRD patients should be treated with peritoneal dialysis to optimize clinical outcomes, and 40% if the aim is optimal cost-effectiveness.¹⁹

Although peritoneal dialysis is underutilized, several approaches in combination may help to substantially increase use of this approach:

Improvements in Dialysis Training. A recent report²⁰ found that many US dialysis training programs do not have enough peritoneal dialysis patients or do not allocate appropriate training time to peritoneal dialysis. There is a risk of creating a vicious cycle: physicians may feel inadequately prepared to provide care for peritoneal dialysis patients, thus further reducing use of peritoneal dialysis and training opportunities.

Early Patient Referral. Late referral of patients with renal insufficiency to renal specialists increases the incidence of the need for acute dialysis initiation with its associated morbidity and mortality.²¹ Acute hemodialysis via temporary vascular access is often the preferred method; once the patient begins hemodialysis, a logistical effort is required to switch to peritoneal dialysis. Late referral per se can halve the incidence of use of peritoneal dialysis.²² Primary care physicians should be encouraged to refer patients early, at the latest when the glomerular filtration rate (GFR) falls below 25 mL/min or the serum creatinine level exceeds 3 mg/dL (265.2 µmol/L). Appropriate coordination with primary care clinicians and other specialties, particularly diabetologists, can reduce late referrals to less than 20%.²²

Early Dialysis Planning. Plasma creatinine and urea levels increase exponentially during preterminal renal failure and do not accurately reflect uremia in the cachectic patient; to avoid being misled, clinicians should assess the GFR regularly (eg, by using the Modification of Diet in Renal Disease Study Group formulae).²³ Dialysis education should be provided at the latest when the GFR decreases to less than 15 mL/min per 1.73 m². At this level, uremic symptoms are mild for many patients, but dialysis modality choices should be made and access planned. Patient education is an important goal, since patients are better empowered to make the most appropriate choice for their own social and medical situation. In practice, the number of patients choosing, and actually starting, peritoneal dialysis increases with increased education about renal failure and treatment options.¹⁰ The finding by Rubin et al¹¹ that peritoneal dialysis patients felt much better informed about the choice of modalities is probably a consequence of this. The US Renal Data System Wave Study²⁴ found that only 25% of hemodialysis patients remembered being informed about peritoneal dialysis, suggesting that this is clearly an area for improvement.

Efficient Access Procedures. Long waiting times to dialysis access also increase the risk of acute dialysis requirement. The technique of peritoneal dialysis catheter placement is probably of lesser importance for most patients in that operative, laparoscopic, and percutaneous methods have similar success rates.²⁵ A more important factor for a successful catheter placement program is the existence of a dedicated catheter team. An advantage of percutaneous and laparoscopic methods is that they can be incorporated into a nephrology outpatient service, thus further shortening waiting times.²⁶ However, few programs provide this facility¹³

Agencies That Provide Funding for ESRD Care Should Find Peritoneal Dialysis Attractive. As a home therapy, the overall costs of peritoneal dialysis are lower than costs at dialysis centers and satellite hemodialysis centers.^{27 - 28} However, as Rubin et al point out, perverse economic signals can reduce the prevalence of peritoneal dialysis. Once a hemodialysis station is established, there is an economic imperative to fill all dialysis slots; fee-for-service funding may discriminate against home dialysis.

Patient choice, trained physicians, early referral, early dialysis planning, increased patient education, short waiting times, and rational funding are all desirable goals and markers of a well-run ESRD program. Peritoneal dialysis prevalence rates could indeed be considered a useful marker of program quality.