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More than 200,000 Americans are affected by chronic kidney and urologic disease to the point where they need dialysis in order to stay alive, and persons over the age of 65 are soon expected to make up the majority of those requiring maintenance dialysis therapy.
Though these individuals tend to have an increased number of
comorbid conditions that create challenges for the health care
team, both hemodialysis and peritoneal dialysis can be successful
treatment modalities for these patients. This is especially true
when attention is given to the altered physiologic adaptation,
comorbid medical conditions, and specific psychosocial needs that
accompany the process of aging.
Before 1960, the inevitable decline of patients with end-stage renal disease (ESRD) could not be reversed or slowed. In that year researchers developed the external shunt, which provided repeated vascular access to enable effective use of the dialysis technology that had been developed some years earlier. Chronic intermittent hemodialysis began in 1960 at the University of Washington; 10 years later, Congress mandated Medicare coverage for ESRD, regardless of the patient's age, opening the door for hundreds of thousands of patients to receive life-saving dialysis therapy.
Treated ESRD occurs at a rate of 180 per million persons in the United States and is rising at a rate of 7.8% a year. In 1990, more than 45,000 new patients were enrolled in the Medicare ESRD program; of these patients, 43% were at least 64 years of age.
Hypertension and diabetes accounted for 63% of new cases of treated ESRD in 1990; of the more than 195,000 patients receiving renal replacement therapy during that year, 70% were being treated with either hemodialysis or peritoneal dialysis.
Kidney transplantation remains the treatment of choice for many persons with ESRD; however, transplantation rates for elderly patients remain low. This is due largely to the presence of comorbid conditions, and a shortage of cadaveric organs-however an active, healthy elderly person who has been carefully screened and has no contraindications is still considered a potential candidate for transplantation.
The total cost of care for patients with ESRD in 1990 was approximately $7.26 billion, an increase of 21% over the preceding year. According to an analysis by the Health Care Financing Administration, it is estimated that more than 300,000 persons will be enrolled in the ESRD program by the year 2000, with 85,000 of them entering the program as new patients in the year 2000 alone. Most of the increase is expected to come from the elderly and diabetes populations.
Morbidity and mortality in the ESRD population is high. At age
49, the expected duration of life for an ESRD patient is seven
years, compared with 30 years for an individual of the same age
from the general population. In 1986, for all Medicare patients over the age of
65, hospitalization averaged 2.8 days per year; for those on dialysis, the median was 15 days a year.
Despite lower group survival rates and a higher incidence of hospitalizations compared with younger patients, many elderly patients have been shown to tolerate dialysis therapy quite well and have been able to maintain a good quality of life. Both hemodialysis and peritoneal analysis are suitable for this patient population; however, particular psychosocial factors related to aging must be taken into account in formulating an individualized dialysis regimen.
"Probably the greatest thing you can do for the elderly patient is to give them time," Evyline Porter, RN, renal coordinator for the Toronto Hospital in Toronto, Ontario, said during an address last year at the fourth International Conference on Geriatric Nephrology and Urology.
"The elderly take longer to process information, they take longer to adapt to change, they have more comorbid disease and disability, and they quite often take longer to respond to therapy," continued Porter. "Additional time allows the elderly patient to understand his or her disease and overcome shock and grieving while the physician assesses the patient's physical and mental capacities.
"Time can allow both parties to explore dialysis options and develop a customized plan, and permits a longer, less intense period of dialysis training and preparation." It also allows the patient and family to develop a good relationship with the health care team, added Porter.
Another option to consider with elderly patients is to conduct a trial of dialysis, which allows the patient and family extra time to decide whether they think long-term dialysis will be appropriate. And, with dialysis withdrawal becoming increasingly common among elderly ESRD patients, the need for completion of advanced directives might be a topic to explore.
Dialysis should probably be started sooner rather than later in elderly patients because of the possibility of physical and mental decline and the increased likelihood of comorbid conditions. Nearly 63% of patients 75 years of age or older have at least two comorbidities when they start dialysis.
These patients should not be given too much information at one time, to avoid the possibility of overwhelming them. Provide information slowly over time, and always ask them if they would like further explanations.
The patient should be referred to a renal health care team when the serum creatinine has reached 1.5 mg/dl in women and 2.0 mg/dl in men.
Factors influencing morbidity and mortality in dialysis patients of any age come into play long before the need for dialysis is imminent: these include anemia, hypertension, malnutrition, renal osteodystrophy, lipid abnormalities, metabolic acidosis, and poor glycemic control in patients with diabetes. Early intervention in the pre-dialysis period can prevent emergency dialysis, which jeopardizes the patient's ability to choose a dialysis modality, endangers the ability to ensure prolonged vascular access, necessitates hospitalization for a catastrophic illness, and produces mortality figures as high as 25%.
Intervention in the pre-dialysis period concentrates on reversing hypertension, treating anemia, and correcting nutritional deficiencies and acidosis. Accumulating evidence suggests that aggressive treatment of anemia is as important in the pre-dialysis period as it is during dialysis, serving to improve or maintain functional capacity and nutritional adequacy and reduce sensitization to transplant antigens associated with transfusion. Subcutaneous use of the parathyroid hormone erythropoietin (Epogen), which stimulates the bone marrow to produce red blood cells, helps prevent severe anemia. Though a target hematocrit has not yet been determined, it is currently recommended that the hematocrit be maintained above 30%.
Because of the negative effects of the parathyroid hormone,
therapies aimed at preventing or reversing secondary hyperparathyroidism
(such as phosphate restriction and use of phosphate binders) should
also begin in the pre-dialysis period.
One of the most powerful interventions to take in the pre-dialysis period is treatment of hypertension to normalize systolic and diastolic pressure. It has been suggested that delay of adequate therapy for hypertension can result in changes that are irreversible or only slowly reversible on dialysis, including the development of left ventricular hypertrophy and diastolic dysfunction. Antihypertensive therapy in patients with chronic renal insufficiency should target the control of both hypertension and proteinuria. Angiotensin-converting enzyme (ACE) inhibitors and nondihydropyridine calcium channel blockers such as diltiazem have been shown to be beneficial.
Factors associated with renal osteodystrophy should also be addressed
in the pre-dialysis period to prevent severe hyperparathyroidism.
Instruct patients about dietary phosphate restriction, and initiate
therapy with calcium-containing phosphate binders when minimal
elevations of phosphate occur. Aggressive treatment of metabolic
acidosis to maintain bicarbonate near the normal range will help
prevent bone dissolution and inhibit osteoblastic activity, and
may improve protein metabolism.
A nutrition assessment is advisable at an early date in the pre-dialysis period; this should include weight, height, recent weight loss, upper arm anthropometry, and serum proteins. In the absence of obvious malnutrition, it has been suggested that restricting dietary protein to between 0.7 and 0.8g/Kg a day, coupled with adequate calorie intake of 35 kcal/kg a day, can help patients maintain their nutritional status without placing an undue burden on their capacity to eliminate potentially toxic metabolites such as acid, potassium, sulfate, phosphorus, magnesium, and uremic toxins. If the patient is malnourished, greater amounts of dietary protein-up to 1 to 1.2 kg-may be advisable.
It is essential that malnutrition, as indicated by a decrease in albumin and body weight, not be allowed to develop in pre-dialysis patients. Serum albumin levels lower than 3.5 g/dl have been associated with dramatic increases in mortality.
Fluid retention in some patients may make nutrition assessment more difficult; in these cases, new techniques, including multifrequency bioimpedance analysis and dual emission x-ray absorptiometry, may help assess states of fluid overload and bone mineral status, respectively.
The dietitian will customize dietary recommendations for proteins,
fat, carbohydrate, fluid, sodium, and phosphate, along with other
micronutrients. The diet may be modified to minimize lipid abnormalities
such as hypertriglyceridemia and reduced high-density lipoprotein
(HDL) cholesterol, though there are limited data supporting the
efficacy of these measures in reducing such abnormalities.
Early establishment of vascular access-either through arteriovenous
(A-V) fistula surgery, which creates a shunt out of the patient's
blood vessels; through creation of a synthetic graft; or through
placement of a peritoneal dialysis catheter-provides a considerable
advantage for the patient. A-V fistula surgery must occur months
before dialysis is started to allow maturation of the fistula
(which can take two to three months to mature), and a peritoneal
catheter should be placed at least one month prior to its anticipated
use. If these procedures are performed too late, the need for
emergency dialysis increases, as does the probability of long-term
access problems and other complications.
Dialysis-related complications include infection, vascular access problems, amyloidosis, and imbalances of calcium, phosphorus, vitamin D, and parathyroid hormone, in addition to continuation of problems encountered in the pre-dialysis period.
One of the major problems affecting elderly dialysis patients involves vascular access. A satisfactory fistula cannot be established in many of these patients because of inadequate vessels. Also, if the A-V fistula surgery is performed too late, the patient will require placement of a temporary catherter while the A-V fistula is maturing. Unfortunately, repeated use of temporary subcutaneous catheters may be accompanied by infection or thrombosis, and should be avoided if at all possible.
When an A-V fistula is not feasible, a synthetic graft is placed; however, more than half of these grafts fail because of thrombosis, primarily due to anatomic stenosis. Other failures are due to excessive postvenepuncture pressure by manual compression or clamp, or by the patient sleeping on the graft. Synthetic grafts generally last no more than two years, with failure due to thrombosis occurring in 80% of cases, and infection in 20%.
Warning signs of incipient failure of a graft include elevated venous dialysis pressure or an increase in recirculation; if these signs are attended to promptly, clotting
of the graft may be prevented.
measuring dialysis efficacyThe fractional urea clearance during dialysis has recently been proposed as a better way to measure dialysis efficacy than traditional measures of serum creatinine and urea and estimates of dialysis delivery (square meter hour). The new measurement process uses urea as a marker for uremic toxins cleared during the dialysis procedure. The fractional urea clearance model for delivered hemodialysis dose is expressed as Kdrt/V, where Kd is dialyzer clearance (ml/min), r is residual renal urea clearance (ml/min), t is treatment time (min), and V is total-body urea distribution volume in a single pool (ml). A simpler and more common measurement of fractional urea clearance during a single dialysis treatment is the urea reduction ratio (URR). This ratio is expressed as a percentage and is calculated as [(pre-dialysis BUN) (post-dialysis BUN)/pre-dialysis BUN] ¥ 100. An approximate relationship between these two means of expressing dialysis dose can be made: Kdrt/V of 1.2 is approximately equal to URR 60%. Although urea may be distributed in multiple body pools, current measurements use a single-pool model to calculate urea clearence.
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Fifteen to thirty percent of dialysis-related mortalities are ascribed to infections; these infections are usually due to common organisms. Approximately 60% of bacteremic infections in dialysis patients are due to gram-positive organisms, especially Staphylococcus aureus.
Fifty to sixty percent of dialysis patients are carriers of S. aureus, compared with 10% to 30% of the general population; though prophylactic antibiotic use could potentially reduce this carrier rate, it could, in turn, encourage the emergence of resistant organisms.
Some emerging information suggests that use of bioincompatible membranes may mediate some negative effects on white cell function and other defense mechanisms, and a few studies have suggested that a switch to biocompatible dialyzers may lower the incidence of infection by as much as 50% in dialysis patients.
Recurrent peritonitis is a problem for many elderly peritoneal
dialysis patients; this can often be traced to catheter tunnel
infection. Changes in catheter design (swan-neck catheters, for
example) and placement, and the use of prophylactic antibiotics
at the time of placement, can sometimes prevent these infections.
Amyloidosis-caused by deposits of beta-2 microglobulin protein as amyloid-can be a particular problem in elderly dialysis patients, especially those who have been undergoing dialysis for more than six years. This disorder can cause carpal tunnel syndrome, destructive arthropathy, and cystic bone disease.
Since some evidence indicates that amyloidosis occurs less frequently in patients dialyzed with high-flux membranes than in patients dialyzed with cellulosic membranes, consideration should probably be given to the use of high-flux membranes for patients who are experiencing or who are at risk of developing amyloidosis-however, the treatment of choice for these patients is renal transplantation.
Imbalances in body calcium, phosphorus, vitamin D, and parathyroid hormone continue to be an issue as long as a patient is on dialysis. Such imbalances requires control of dietary phosphorus, use of phosphate binders to minimize phosphate absorption, and the use of calcitriol to treat secondary hyperparathyroidism. Calcitriol dosages should be carefully titrated to prevent hyperphosphatemia or hypercalcemia.
Use of calcium carbonate or calcium acetate with meals will help most patients prevent absorption of phosphorus but may require adjustments in the concentration of dialysate fluid to prevent hypercalcemia.
Careful control of dietary phosphorus, calcium salts, and calcitriol
will often enable the patient to maintain parathyroid concentrations
at or near normal levels.
Recently, questions have arisen regarding the relationship of delivered dialysis dose to patient morbidity and mortality. Historically, adequacy has been determined by measuring serum creatinine and urea.
Estimates of fractional urea clearance during dialysis are now being suggested as more reliable in measuring dialysis efficacy (see sidebar); several studies have also suggested that the dialysis dose delivered to many hemodialysis patients in the United States is less than optimal.
At a Consensus Development Conference convened in 1993 by the National Institute of Diabetes and Digestive and Kidney Diseases and the Office of Medical Research of the National Institutes of Health, a recommendation was made for a minimum delivered hemodialysis of Kt/V of 1.2 and a delivered peritoneal dialysis dose at least equal to a measured Kt/V of 1.7 weekly. Recently, new guidelines have higher standards: minimum delivered hemodialysis of Kt/V or 1.3-1.4; and delivered peritoneal dose of at least 2.0-2.1.
The consensus development conference also recommended incorporating financial support into the budgets of the Medicare End-Stage Renal Disease Program, the Health Care Financing Administration, the Agency for Health Care Policy and Research, and the Food and Drug Administration to conduct studies to improve morbidity and mortality, enhance cost-effective care, and improve the quality of life for the hundreds of thousands of Americans, including dialysis patients, who are affected by ESRD.
Selected Resources
Cotton SL, Holechek MJ. Management of anemia using recombinant
human erythropoietin in patients on chronic hemodialysis. Anna
J 1989;16(7):463-68.
Erlich L. Use of EPOGEN for treatment of anemia associated with
chronic renal failure. Crit Care Nurs Clin North Am 1990;2(1):101-13.
Gaughan WJ, Liss KA et al. A 6-month study of low-dose recombinant
human erythropoietin alone and in combination with androgens for
the treatment of anemia in chronic hemodialysis patients. Am J
Kidney Dis 1997;30(4):495-500.
Latos DL. Chronic dialysis in patients over age 65. J Am Soc Nephrol
1996;7(5):637-46.
Lindeman RD. Assessment of renal function in the old. Special considerations. Clin Lab Med 1993;13(1):269-77.
Lubran MM. Renal function in the elderly. Ann Clin Lab Sci 1995;25(2):122-33.
National Institutes of Health Consensus Statement on the Morbidity
and Mortality Rates of Dialysis, November, 1993.
Nazem AK, Mako J. The effect of calcitriol on renal anemia in
patients undergoing long-term dialysis. Int Urol Nephrol 1997;29(1):119-27.
National Kidney Foundation. www.nkf.org.sg/newnkf/facts.htm.
RenalNet Nephrology Resources. www.renalnet.org.
Zazgornik J, Biesenbach G, Forstenlehner M et al. Profile of antihypertensive
drugs in hypertensive patients on renal replacement therapy. Clin
Nephrol 1997; 48(6):337-40.
Minhtri Nguyen, MD, is a practicing physician and clinical faculty member in the Adult Nephrology Division of the University of California, Los Angeles Medical School.
Copyright © 1998, The Consultant Pharmacist.