Canadian Hemodialysis Morbidity Study

Clinical consequences of infected arteriovenous grafts in hemodialysis patients

Arteriovenous (AV) graft infection is a serious adverse event in hemodialysis patients; however, there is little published literature describing its consequences. We identified prospectively all AV graft infections occurring at our institution during a 4.5-year period. We analyzed immediate complications, as well as long-term consequences, including the need for subsequent vascular-access procedures and duration of catheter-dependent dialysis therapy. Ninety graft infections were identified in 78 patients, yielding a rate of 8.2 infections/100 graft-years. Patients with graft infection were much more likely to have a low serum albumin level (<3.5 g/dL) in the month preceding the infection compared with noninfected controls (73% versus 18%; P < 0.001). Infections occurred within 1 month of graft placement in 15%, at 1 to 12 months in 44%, and longer than 1 year from surgery in 41%. The pathogen was a gram-positive coccus in 97% of cases, particularly Staphylococcus aureus (60%) and Staphylococcus epidermidis (22%). The initial graft infection entailed hospitalization for a mean of 7.5 days. Eleven patients (12%) developed a total of 17 major complications, including death (5 patients), clinical sepsis requiring vasopressors (4 patients), septic arthritis (3 patients), epidural abscess (1 patient), endocarditis (1 patient), osteomyelitis (1 patient), myocardial infarction (1 patient), and cerebrovascular accident (1 patient). After removal of an infected graft, patients were catheter dependent for a median of 3.8 months. The duration of catheter dependence was less than 3 months in 36%, 3 to 6 months in 38%, 6 to 12 months in 14%, and greater than 1 year in 12%. During the period of catheter dependence, patients required a mean of 9.7 access procedures, including graft removal (1.0 procedure), nontunneled dialysis catheters (4.4 procedures), tunneled dialysis catheters (3.0 procedures), and new permanent accesses (1.4 procedures). In addition, patients averaged 0.85 episodes of bacteremia while they were catheter dependent. In conclusion, graft infection results in substantial morbidity, prolonged dependence on dialysis catheters, and multiple vascular-access procedures.

Effect of preoperative sonographic mapping on vascular access outcomes in hemodialysis patients

BACKGROUND

Current DOQI guidelines encourage placing arteriovenous (AV) fistulas in more hemodialysis patients. However, many new fistulas fail to mature sufficiently to be usable for hemodialysis. Preoperative vascular mapping to identify suitable vessels may improve vascular access outcomes. The present study prospectively evaluated the effect of routine preoperative vascular mapping on the type of vascular accesses placed and their outcomes.

METHODS

During a 17-month period, preoperative sonographic evaluation of the upper extremity arteries and veins was obtained routinely. The surgeons used the information obtained to plan the vascular access procedure. The types of access placed, their initial adequacy for dialysis, and their long-term outcomes were compared to institutional historical controls placed on the basis of physical examination alone.

RESULTS

The proportion of fistulas placed increased from 34% during the historical control period to 64% with preoperative vascular mapping (P < 0.001). When all fistulas were assessed, the initial adequacy rate for dialysis increased mildly from 46 to 54% (P = 0.34). For the subset of forearm fistulas, the initial adequacy increased substantially from 34 to 54% (P = 0.06); the greatest improvement occurred among women (from 7 to 36%, P = 0.06) and diabetic patients (from 21 to 50%, P = 0.055). In contrast, the initial adequacy rate of upper arm fistulas was not improved by preoperative vascular mapping (59 vs. 56%, P = 0.75). Primary access failure was higher for fistulas than grafts (46.4 vs. 20.6%, P = 0.001), but the subsequent long-term failure rate was higher for grafts than fistulas (P < 0.05). Moreover, grafts required a threefold higher intervention rate (1.67 vs. 0.57 per year, P < 0.001) to maintain their patency. The overall effect of this strategy was to double the proportion of patients dialyzing with a fistula in our population from 16 to 34% (P < 0.001).

CONCLUSIONS

Routine preoperative vascular mapping results in a marked increase in placement of AV fistulas, as well as an improvement in the adequacy of forearm fistulas for dialysis. This approach resulted in a substantial increase in the proportion of patients dialyzing with a fistula in our patient population. Fistulas have a higher primary failure rate than grafts, but have a lower subsequent failure rate and require fewer procedures to maintain their long-term patency.

Type of vascular access and mortality in U.S. hemodialysis patients

BACKGROUND

Vascular access (VA) complications account for 16 to 25% of hospital admissions. This study tested the hypothesis that the type of VA in use is correlated with overall mortality and cause-specific mortality.

METHODS

Data were analyzed from the U.S. Renal Data System Dialysis Morbidity and Mortality Study Wave 1, a random sample of 5507 patients, prevalent on hemodialysis as of December 31, 1993. The relative mortality risk during a two-year observation was analyzed by Cox-regression methods with adjustments for demographic and comorbid conditions. Using similar methods, cause-specific analyses also were performed for death caused by infection and cardiac causes.

RESULTS

In diabetic mellitus (DM) patients with end-stage renal disease, the associated relative mortality risk was higher for those with arteriovenous graft (AVG; RR = 1.41, P < 0.003) and central venous catheter (CVC; RR = 1.54, P < 0.002) as compared with arteriovenous fistula (AVF). In non-DM patients, those with CVC had a higher associated mortality (RR = 1.70, P < 0.001), as did to a lesser degree those with AVG (RR = 1.08, P = 0.35) when compared with AVF. Cause-specific analyses found higher infection-related deaths for CVC (RR = 2.30, P < 0.06) and AVG (RR = 2.47, P < 0.02) compared with AVF in DM; in non-DM, risk was higher also for CVC (RR = 1.83, P < 0.04) and AVG (RR = 1.27, P < 0.33). In contrast to our hypothesis that AV shunting increases cardiac risk, deaths caused by cardiac causes were higher in CVC than AVF for both DM (RR = 1.47, P < 0.05) and non-DM (RR = 1.34, P < 0.05) patients.

CONCLUSION

This case-mix adjusted analysis suggests that CVC and AVG are correlated with increased mortality risk when compared with AVF, both overall and by major causes of death.

Late referral and modality choice in end-stage renal disease

BACKGROUND

We sought to determine whether late versus early referral to a nephrologist in patients with chronic kidney disease influences the initial choice of hemodialysis (HD) versus peritoneal dialysis (PD) or the likelihood of switching treatment modalities in the first six months of therapy.

METHODS

Using New Jersey Medicare/Medicaid claims, all patients who started RRT between January 1991 and June 1996 and were diagnosed with renal disease more than one year prior to RRT were identified. In the resulting cohort of 3014 patients, 35% had their first nephrologist consultation < or =90 days prior to initiation of dialysis.

RESULTS

After controlling for demographic characteristics, socioeconomic status and underlying renal disease, age, black race [Odds ratio (OR) = 0.56], race other than black or white (OR = 0.56), and socioeconomic status (OR = 0.68) influenced the choice of initial treatment modality, but timing of the referral did not. However, patients starting on PD who were referred late were 50% more likely to switch to HD than were patients who saw a nephrologist earlier [Hazard's ratio (HR) = 1.47]. In patients originally on HD, diabetic nephropathy (HR = 1.49) and black race (HR = 0.69) influenced the likelihood of switching to PD, but the timing of referral did not.

CONCLUSIONS

These results refute earlier findings that late referral may limit access to PD. We found that modality choice depends on factors such as age, race, or socioeconomic status, rather than on than timing of nephrologist referral. Late referral does not influence the likelihood to switch modality in patients starting on HD, but does so in patients starting on PD.

Hemodialysis access ultrasound

Maintenance of hemodialysis graft and fistula patency is becoming even more important as the number of patients with end-stage renal disease increases. There are two major categories of dialysis access: native arteriovenous fistula (AVF) and synthetic arteriovenous graft. Arteriovenous fistulas have superior longevity after maturation and are the recommended type of hemodialysis access, if possible. However, AVFs have a higher rate of primary failure as compared with grafts. Close monitoring has been shown to prolong access survival. Ultrasound is a noninvasive means of imaging for access complications. Ultrasound is sensitive in detection of access or draining vein stenosis. Ultrasound is also useful in the evaluation of other graft or fistula abnormalities, such as pseudoaneurysm, steal, or infection. Careful attention to technical detail is required, and avoidance of several diagnostic pitfalls is necessary.

Infections in patients with end-stage renal disease. An overview

One of the best kept secrets in medicine is the problem of infections in patients with end-stage renal disease. The prescription of chronic hemodialysis has not reduced the problem of infection; it has only changed the paradigm. Dialysis superimposes myriad new problems onto patients with relentless deterioration from underlying multisystem disease and poor wound healing. All end-stage renal disease and transplant programs require the input from an individual with the specialized knowledge of laboratory diagnosis, pharmacokinetics of antibiotics, antibiotic choice, antimicrobial resistance, infection control, and infection prevention. This article gives an overview of some of the complexities of infectious problems experienced by this unique biological model.

Timing of nephrologist referral and arteriovenous access use: the CHOICE Study

Recent clinical practice guidelines recommend the creation of an arteriovenous (AV) vascular access (ie, native fistula or synthetic graft) before the start of chronic hemodialysis therapy to prevent the need for complication-prone dialysis catheters. We report on the association of referral to a nephrologist with duration of dialysis-catheter use and type of vascular access used in the first 6 months of hemodialysis therapy. The study population is a representative cohort of 356 patients with questionnaire, laboratory, and medical record data collected as part of the Choices for Healthy Outcomes in Caring for End-Stage Renal Disease Center Study. Patients who reported being seen by a nephrologist at least 1 month before starting hemodialysis therapy (75%) were more likely than those referred later to use an AV access at initiation (39% versus 10%; P < 0.001) and 6 months after starting hemodialysis therapy (74% versus 56%; P < 0.01). Patients referred within 1 month of initiating hemodialysis therapy used a dialysis catheter for a median of 202 days compared with 64, 67, and 19 days for patients referred 1 to 4, 4 to 12, and greater than 12 months before initiating hemodialysis therapy, respectively (P trend < 0.001). Patients referred at least 4 months before initiating hemodialysis therapy were more likely than patients referred later to use an AV fistula, rather than a synthetic graft, as their first AV access (45% versus 31%; P < 0.01). These associations remained after adjustment for age, sex, race, marital status, education, insurance coverage, comorbid disease status, albumin level, body mass index, and underlying renal diagnosis. These data show that late referral to a nephrologist substantially increases the likelihood of dialysis-catheter use at the initiation of hemodialysis therapy and is associated with prolonged catheter use. Regardless of the time of referral, only a minority of patients used an AV access at the initiation of treatment, and greater than 25% had not used an AV access 6 months after initiation. Thus, further efforts to improve both referral patterns and preparation for dialysis after referral are needed.

Conversion between bromcresol green- and bromcresol purple-measured albumin in renal disease

BACKGROUND

Albumin measured by a bromcresol purple dye-binding assay (Alb(BCP)) agrees more closely with the gold standard of immunonephelometry than does bromcresol green (Alb(BCG)) measurement. Both tests are in current clinical use. A method for converting between the two would be useful.

METHODS

We measured albumin by bromcresol green and bromcresol purple in 535 patients, 155 of whom had renal disease. We randomly divided data from the patients with renal disease into two equal-sized sets, and used one set to derive, and the remaining set to validate, a regression equation relating the two values.

RESULTS

The relationship Alb(BCG)=5.5+Alb(BCP) performed very well in both the renal patient validation set and in the data from 380 unselected in-patients and out-patients. Intraclass correlations for agreement between measured Alb(BCG) and predicted Alb(BCG) was 0.98 in both analyses.

CONCLUSIONS

The ability to convert between these measurements will be of use in clinical situations where the absolute value of the serum albumin is important, when data from laboratories using different methodologies must be combined, and in the application of the Modification of Diet in Renal Disease formula to estimate glomerular filtration rate in patients whose albumin has been measured by bromcresol purple.

NUTRITIONALMANAGEMENT OFMAINTENANCEDIALYSISPATIENTS: Why Aren't We Doing Better?

About 40% of patients undergoing maintenance dialysis suffer from varying degrees of protein-energy malnutrition. This is a problem of substantial importance because many measures of nutritional status correlate with the risk of morbidity and mortality. There are many causes of protein-energy malnutrition in maintenance dialysis patients. Evidence indicates that nutritional decline begins even when the reduction in glomerular filtration rate is modest, and it is likely that the observed decrease in dietary protein and energy intake plays an important role. The nutrient intake of patients receiving maintenance dialysis also is often inadequate, and several lines of evidence suggest that toxins that accumulate with renal failure suppress appetite and contribute to nutritional decline once patients are on maintenance dialysis. Recent epidemiologic studies have suggested that both increased serum levels of leptin and inflammation may reduce nutrient intake and contribute to the development of protein-energy malnutrition. It is likely that associated illnesses, which are highly prevalent, contribute to malnutrition in maintenance dialysis patients. Recent data from the United States Renal Data System registry suggest that in the United States, the mortality rate of dialysis patients is improving. However, it remains high. We offer suggestions for predialysis and dialysis care of these patients that can result in improvement in their nutritional status. Whether this improvement will result in a decrease in patient morbidity and mortality is unknown.

Serial prealbumin levels as predictors of outcomes in a retrospective cohort of peritoneal and hemodialysis patients

OBJECTIVE

Although earlier research has suggested that baseline prealbumin level is an independent predictor of outcome among dialysis patients, the prognostic importance of serial prealbumin levels is less clear. The present study had 3 objectives: first, to determine if prealbumin (a marker of visceral protein stores with a relatively short half-life) predicts subsequent albumin levels taken at least 1 month later; second, to examine the association between serial prealbumin levels and clinical outcome; and third, to examine the association between changes in prealbumin level and outcome.

DESIGN

The prognostic value of serial prealbumin levels was examined by linear regression analysis and Cox hazard models in an observational cohort study using a repeated measures design and time-dependent covariates.

SETTING

Patients were followed by a tertiary care center, receiving hemodialysis (HD; at either an in-center dialysis unit or one of several satellite units operated by the hospital) or home peritoneal dialysis (PD).

PATIENTS

A retrospective cohort was identified consisting of 268 incident and prevalent chronic HD and PD patients receiving dialysis from June 1998 to September 1999.

MAIN OUTCOME

The study examined the association between serial prealbumin measurements and future laboratory and clinical outcomes (albumin, hospitalization, and death).

RESULTS

Serial prealbumin values were independent predictors of future albumin levels among HD patients (P =.04), but not PD patients. Independent predictors of hospitalization included diabetes for PD patients (P =.0012) and advanced age for HD patients (P =.0008). Advanced age and diabetes were independent predictors of death for both HD (P =.0001 and P =.0368) and PD patients (P =.0014 and P =.0164). Serial prealbumin values, measured as time-dependent covariates, did not predict hospitalization or death. Further analyses examined the prognostic value of changes in prealbumin and albumin values as time-dependent covariates. The final multivariate analysis identified low baseline albumin level as an independent predictor of hospitalization among HD patients (P =.0282), whereas low baseline prealbumin was an independent predictor of death for HD patients (P =.0001). Interestingly, negative changes in serial prealbumin measurements were also independent predictors of death among HD patients (P =.0025).

CONCLUSION

Serial prealbumin measurements predict subsequent albumin values among HD patients. As well, low baseline prealbumin level is an independent predictor of adverse outcome among HD patients. Although repeated prealbumin measurements in and of themselves were of no added prognostic value, falling prealbumin values identified by repeated measurements were additional independent predictors of death. These results support the clinical utility of regular prealbumin monitoring among HD patients.

Infectious complications of the hemodialysis access

Infectious complications of the vascular access are a major source of morbidity and mortality among hemodialysis (HD) patients. Numerous reports implicate the vascular access in up to 48 to 73% of all bacteremias in HD patients. The incidence of vascular access-related infection is highest when central venous dialysis catheters are employed. Native arteriovenous fistulas carry the lowest risk of infection. Unfortunately, prosthetic arteriovenous grafts, which represent the most common type of HD access in the United States, have been repeatedly shown to be a risk factor for bacteremic and nonbacteremic infections. Silent infection in old nonfunctional clotted prosthetic arteriovenous grafts has recently been recognized as a frequent cause of bacteremia and morbidity among HD patients. High proportions of infections related to the vascular access are caused by staphylococcal organisms, which carry high rates of mortality, recurrence, and metastatic complications. Management of vascular access-related infection has two aspects: The first relates to the choice, duration, and mode of administration of antibiotic therapy. Empiric antibiotic therapy, guided by demographic data and severity of illness, should be employed when the causative organisms are unknown. Prolonged administration of specific parenteral antibiotics is crucial in decreasing complications of infection, especially in cases of staphylococcal bacteremia. The second aspect relates to management of the vascular access. Efforts directed toward bacteriological cure should be concurrent with efforts to preserve native venous access sites whenever possible. Efforts to prevent vascular access-related infection should focus on increasing placement of arteriovenous fistulas and minimizing insertion of central venous dialysis catheters. Careful inspection and monitoring of the vascular access is of paramount importance in early detection of vascular access site-related infections. Several new approaches aimed at preventing catheter and prosthetic graft-related infection are being explored.

Infections associated with uremia and dialysis

Patients with chronic renal failure are predisposed to infections. Infections in end-stage renal disease patients are caused by immunosuppressive effects of uremia. Patients with renal failure on dialysis have impaired host defenses and may develop infections related to vascular access. This article reviews the infectious complications related to chronic renal failure in dialysis.

Predictors of arteriovenous graft patency after radiologic intervention in hemodialysis patients

Arteriovenous grafts in hemodialysis patients are prone to recurrent stenosis and thrombosis, requiring frequent radiologic and surgical interventions to optimize their long-term patency. Little is known about the factors that determine graft outcome after a radiologic intervention. The present study examined the clinical and radiologic predictors of intervention-free graft survival after elective angioplasty or thrombectomy. A prospective computerized database was used to determine the outcomes subsequent to all graft angioplasties (n = 330) and thrombectomies (n = 326) performed at the University of Alabama at Birmingham between April 1, 1996, and June 30, 1999. Primary graft survival rates after angioplasty and thrombectomy were 86% versus 43% at 1 month, 71% versus 30% at 3 months, 51% versus 19% at 6 months, and 28% versus 8% at 12 months, respectively. The median intervention-free graft survival time was substantially longer after angioplasty than thrombectomy (6.7 versus 0.6 months; P < 0.001). The superior outcome of angioplasty over thrombectomy was observed even for the subset of procedures with no residual stenosis (median survival, 6.9 versus 2.5 months; P < 0.001). The median graft survival was inversely related to the magnitude of residual stenosis for both elective angioplasty and thrombectomy. Median intervention-free graft survival after angioplasty was inversely related to the postangioplasty intragraft to systemic systolic pressure ratio (7.6, 6.9, and 5.6 months for ratios <0.4, 0.4 to 0.6, and >0.6, respectively; P < 0.001). Intervention-free graft survival after angioplasty or thrombectomy was not affected by graft location (forearm versus upper arm), number of stenotic sites, or presence of diabetes. In conclusion, graft survival is substantially longer after elective angioplasty than thrombectomy, even when the radiologic appearance after the procedure suggests complete resolution of the stenotic lesion. Moreover, the risk for requiring a subsequent graft intervention can be predicted from two simple radiologic measurements: grade of stenosis and intragraft to systemic systolic blood pressure ratio. These parameters may help determine the frequency of monitoring for recurrent stenosis in a given graft.

Baseline blood pressure and other variables influencing survival on haemodialysis of patients without overt cardiovascular disease

BACKGROUND

Age, diabetes and concomitant cardiovascular disease, recorded at the initiation of dialysis, allows the identification of patients with a high probability of early mortality. When all of these factors are taken into account the mortality rate of dialysis patients is still 3.5 times higher than for the general population. Information on the factors that increase the mortality of patients lacking the major cardiovascular risk factors is important because these are likely to be correctable, especially if detected early.

METHODS

We investigated prospectively the relevance of blood pressure and other variables recorded at the initiation of dialysis treatment on the survival of a group of 103 relatively young adult haemodialysis patients (mean age 44.3 years +/-13 SD), with a low prevalence of comorbidity and a median follow-up period of 79 months. Data were analysed by the Cox proportional regression model and survival curves were constructed by the Kaplan-Meier method.

RESULTS

Forty-four patients died, 20 (46%) of whom as a result of cardiovascular causes. Multivariate analysis showed that mortality was associated with age (P=0.0001), serum creatinine (P=0.005, negative association), left ventricular (LV) mass (P=0.003) and hypertension (P=0.03). Mortality was increased by 7% for each additional year of age, by 0.7% for each 1 g increase in LV mass, and was reduced by 23% for each additional mg/dl of serum creatinine. Hypertensive patients had a higher probability (x2.2) of dying compared with normotensive patients.

CONCLUSIONS

In addition to age and conditions of occult malnutrition, hypertension and LV hypertrophy, when present at the initiation of dialysis, play a major role in the mortality of low risk, relatively young dialysis patients. These potentially correctable factors should be actively sought and treated during the early stage of renal insufficiency to improve prognosis.

Anemia management in patients with chronic renal insufficiency

The introduction of recombinant human erythropoietin (rHuEPO) more than a decade ago provided the first effective treatment for the anemia of chronic renal insufficiency (CRI). The use of rHuEPO in the treatment of anemia has been associated with partial regression of left ventricular hypertrophy among both dialysis and nondialysis patients, and has been shown to reduce the frequency of cardiac complications such as congestive heart failure and number of days of hospitalization among dialysis patients. Despite this evidence, the anemia of CRI remains highly prevalent, underrecognized, and undertreated. A number of considerations arise regarding the management of anemia among patients with CRI. In this article, we review the rationale for treatment of anemia, current management practices, proposed treatment strategies, and the economic implications of improved anemia treatment.

Research directions: new clinical frontiers

One of the greatest remaining challenges facing nephrology research is obtaining data with detail and precision for the three large, yet "forgotten," populations that span the spectrum of kidney disease: patients with chronic renal insufficiency (CRI), peritoneal dialysis patients, and kidney transplant patients. Studies of these populations, particularly the CRI group, are hampered by the relative mobility of these patients, the lack of stringent epidemiologic or clinical definitions, and the tendency to extrapolate data from hemodialysis populations into other clinical settings. This article suggests a two-pronged approach to a research agenda: first, by recognizing the need for better data regarding the natural history of these kidney failure subsets and their comorbidities; and second, by directing greater effort at identifying rational, efficacious, and cost-effective interventions to influence their natural history positively. Specific efforts are suggested in all three populations. For patients with CRI, studies should be directed at (1) identifying high-risk patients; (2) determining methods for making optimal referrals to the nephrologist; (3) identifying and managing CRI, its complications, and its comorbid conditions; and (4) establishing processes for the smooth transition to dialysis. The peritoneal dialysis population will benefit from studies addressing the treatment of anemia and its ability to modify cardiovascular illness and quality of life. Kidney transplant studies should also focus on the identification and management of comorbid conditions, as well as the effects of various interventions on quality of life. Rational evidence-based care of these conditions, which are critically important to patients, their families, and the health care system in general, must await the conduct of well-designed prospective observational and interventional trials.

Complications of chronic renal insufficiency: beyond cardiovascular disease

The less rigorous attention to the management of the complications of chronic renal insufficiency (CRI) and its comorbid conditions has potentially tragic consequences. In fact, with early recognition and intervention, many of the complications of CRI and its comorbid conditions can be ameliorated or prevented. We review here the most prevalent, troublesome, and potentially preventable complications and comorbidities of CRI with a view toward developing high-quality, cost-effective strategies for delivering early interventional care. Complications of CRI include malnutrition, anemia, disorders of divalent ion metabolism and osteodystrophy, metabolic acidosis, and dyslipidemia. Important comorbid conditions of CRI are hypertension, diabetes mellitus, and cardiovascular disease. Clinical intuition suggests that early intervention will avert morbidity related to the hypoalbuminemia and other nutritional disorders of CRI, the metabolic acidosis, and the dyslipidemias, but prospective data are lacking at present. Correction of anemia, usually with recombinant human erythropoietin, may be key to the prevention of cardiac disease and other comorbidities of CRI. Incipient disorders of bone and mineral metabolism are managed prospectively using such measures as protein restriction to reduce phosphorus intake, phosphate binders, calcium supplementation, and vitamin D analogues. Hypertension, whatever its original etiology, is clearly an important risk factor for the progression of kidney failure and for the development of diffuse vascular disease; appropriate and aggressive treatment is essential. In patients with diabetic nephropathy, the principles of both primary and secondary prevention have been validated in several large trials of glycemic and blood pressure control. The seeds of these insidious, challenging, and costly comorbid conditions are sown very early in CRI, at a time when they are-in theory-most amenable to intervention. We therefore must be as proactive as possible in the timely implementation of relatively simple therapies that have the potential to prevent some of these adverse outcomes of CRI.

Relation between gender and vascular access complications in hemodialysis patients

Native arteriovenous (AV) fistulae for hemodialysis vascular access are believed to be associated with fewer complications than synthetic polytetrafluoroethylene (PTFE) grafts. We conducted a study among patients in the Dialysis Morbidity and Mortality Study to compare risk factors for complications of AV fistulae and PTFE grafts in men and women and to examine the effect of age on vascular access complications. We analyzed data from 833 incident patients with end-stage renal disease who had a PTFE graft (n = 621) or AV fistula (n = 212) in use 1 month after starting hemodialysis therapy. Follow-up using inpatient and outpatient Medicare administrative data identified a 1.8-times greater risk for a subsequent vascular access procedure for PTFE grafts (0.71 procedures/access-year) than for AV fistulae (0.39 procedures/access-year). Men with grafts and women with grafts or fistulae had a greater risk for a first subsequent access procedure than did men with fistulae (0.79, 0.65, and 0.59 versus 0.33 procedures/access-year, respectively). After adjustment for age, race, presence of diabetes mellitus, and history of smoking, peripheral vascular disease, and cardiovascular disease, use of a PTFE graft compared with an AV fistula was associated with a greater risk for a first subsequent procedure in men (relative hazard, 2.2; 95% confidence interval [CI], 1.6 to 2.9), but not in women (relative hazard, 1.0; 95% CI, 0.7 to 1.4). The excess risk associated with a PTFE graft compared with an AV fistula was limited to men in the lower three quartiles of age (ie, </=72 years). These data raise concern that the potential benefits of AV fistulae over PTFE grafts are not realized in women and older men. A better understanding of the determinants of successful access maturation and maintenance in these groups is needed.

Cross-sectional and longitudinal predictors of serum albumin in hemodialysis patients

BACKGROUND

Lower serum albumin concentrations predict increased mortality in hemodialysis (HD) patients. Many demographic, comorbidity, and modifiable treatment-related factors that predict HD patient outcomes may be associated with serum albumin.

METHODS

Cross-sectional predictors of baseline albumin on December 31, 1993 were sought (N = 3981). Additional effects of the same baseline predictors on subsequent trends in albumin over one year were examined in a nested subsample of patients (N = 2245). Wave-1 of the United States Renal Data System Dialysis Morbidity and Mortality special study provided the data.

RESULTS

Significant associations (P < 0.05) are summarized as older age, female gender, peripheral vascular disease, chronic obstructive pulmonary disease, and cancer predicted a lower baseline albumin and negatively influenced subsequent albumin trends. Baseline albumin was higher for blacks (vs. whites), lower for smoking and diabetes, and lower during the first year of HD treatment (<3 months and 3 to 12 months, vs.> 1 year). Trend analysis showed more positive albumin slopes for patients in their first year on HD and more negative slopes for Native Americans (vs. whites). Baseline albumin was correlated with the type of vascular access being used [arteriovenous (AV) fistulas > AV grafts > permanent catheters > temporary catheters]. Trend analysis predicted more negative albumin slopes for AV grafts and permanent catheters (vs. AV fistula access). Baseline albumin correlated inversely with bicarbonate and directly with hematocrit. Dialysis with unmodified cellulose membranes, without reuse, predicted lower baseline albumin than the other membrane-reuse categories.

CONCLUSIONS

Several exposures, which may be modifiable, were associated with serum albumin.

Retrospective analysis of cisapride-induced QT changes in end-stage renal disease patients

BACKGROUND

This study involves a retrospective in-patient chart review of end-stage renal disease (ESRD) patients receiving haemodialysis to observe if cisapride significantly increases heart rate (HR), QT, and corrected QT (QTc) intervals on 12-lead electrocardiograms (ECGs).

METHODS

Medical records for 23 patients who were being treated with chronic maintenance haemodialysis and had >/=2 ECGs while on cisapride and >/=2 ECGs while off cisapride were obtained and reviewed. HR, QT, and QTc on all 12-lead ECGs, reason for admission, and past medical history were analysed.

RESULTS

A total of 529 ECGs (279 on/250 off cisapride) for 23 patients were included. The results, as calculated by each patient's individual averages (n=23), on vs off cisapride respectively, were HR, 88+/-14 vs 84+/-17 beats/min (P:=0.18); QT, 373+/-39 vs 382+/-45 ms (P:=0.24); and QTc, 443+/-27 vs 441+/-21 ms (P:=0.39). No significant difference was found in the number of admissions per month while on or off cisapride. No patient had an average QTc on or off cisapride that was >500 ms. One patient died from ventricular arrhythmia 12 days after discontinuing cisapride. The patient's QTc was significantly longer on vs off cisapride (487 vs 462 ms, P:=0. 007); however, this patient had an extensive cardiac history and multiple syncopal episodes prior to the use of cisapride.

CONCLUSIONS

This study found no significant overall difference in HR, QT, and QTc interval or admissions/month on vs off cisapride in ESRD patients receiving haemodialysis.

Factors associated with the prevalence of arteriovenous fistulas in hemodialysis patients in the HEMO study. Hemodialysis (HEMO) Study Group

BACKGROUND

Arteriovenous (AV) fistulas are the vascular access of choice for hemodialysis patients, but only about 20% of hemodialysis patients in the United States dialyze with fistulas. There is little information known about the factors associated with this low prevalence of fistulas.

METHODS

Multiple logistic regression analysis was used to evaluate the independent contribution of factors associated with AV fistula use among patients enrolled in the HEMO Study. The analysis was conducted in 1824 patients with fistulas or grafts at 45 dialysis units (15 clinical centers).

RESULTS

Thirty-four percent of the patients had fistulas. The prevalence of fistulas varied markedly from 4 to 77% among the individual dialysis units (P < 0.001). Multiple regression analysis revealed five demographic and clinical factors that were each independently associated with a lower likelihood of having a fistula, even after adjustment for dialysis unit. Specifically, the prevalence of fistulas was lower in females than males [adjusted odds ratio (AOR) 0.37, 95% CI, 0.28 to 0.48], lower in patients with peripheral vascular disease than in those without (AOR 0.55, 95% CI, 0.38 to 0.79), lower in blacks than in non-blacks (AOR 0.64, 95% CI, 0.46 to 0.89), lower in obese patients (AOR per 5 kg/m(2) body mass index, 0.76, 95% CI, 0.65 to 0.87), and lower in older patients (AOR per 10 years, 0.85, 95% CI, 0.78 to 0.94). The differences in the prevalence of fistulas among the dialysis units remained statistically significant (P < 0.001) after adjustment for these demographic and clinical factors. Finally, there were substantial variations in the prevalence of fistulas even among dialysis units in a single metropolitan area.

CONCLUSIONS

Future efforts to increase the prevalence of fistulas in hemodialysis patients should be directed at both hemodialysis units and patient subpopulations with a low fistula prevalence.

Dialysis access infections

Infections and specifically infectious complications of vascular access remain a major cause of morbidity and mortality in the hemodialysis population. Primary arteriovenous fistulas have the lowest rates of infections and are the access of choice whenever vascular anatomy allows. The dialysis outcomes quality initiative (DOQI) guidelines have thus stressed the need for increasing the utilization of arteriovenous fistulas. Unfortunately, comorbid disease processes and late referrals for vascular access have maintained our dependence on synthetic grafts and indwelling catheters. Indwelling catheters, in particular, have the highest rate of infection and are often associated with more serious metastatic complications. Appropriate antibiotics along with aggressive surgical debridement remain crucial in bacteremia occurring in arteriovenous fistulas or synthetic grafts (polytetrafluoroethylene). Catheter related bacteremia necessitates catheter removal with either guidewire exchange or replacement after a period of antibiotic therapy. Measures to increase our utilization of primary fistulas whenever possible will lower the risk of these complications in our patients.

Long-term prognosis and incidence of acute myocardial infarction in patients on chronic hemodialysis. The Okinawa Dialysis Study Group

Mortality from cardiovascular disease is high in chronic dialysis patients. We observed the occurrence of acute myocardial infarction (AMI) in the chronic dialysis population in Okinawa, Japan. A total of 3,741 chronic dialysis patients (2,073 men, 1,668 women) were followed up for 10 years from April 1, 1988, to March 31, 1998. Only definite cases of AMI were registered. Data were compared with AMI registry data obtained from the general population of the same district. The total duration of observation was 15,748.8 patient-years. During the study period, 61 patients (40 men, 21 women) had AMI. The incidence of AMI was 3.9/1,000 patient-years (men, 4.4/1,000 patient-years; women, 3.1/1,000 patient-years). Twenty-four percent of the AMI cases occurred at 12 months after starting dialysis therapy. Mean age at onset of AMI was 60.9 +/- 11. 4 (SD) years; 58.9 +/- 11.4 years in men and 64.7 +/- 10.7 years in women. Survival rates after AMI were 50.8% at 1 month, 45.0% at 6 months, 36.5% at 12 months, and 13.0% at 44 months. Patients with diabetes mellitus (DM) had a greater incidence of AMI and a worse prognosis than patients without DM. The long-term prognosis of AMI was poor in chronic dialysis patients.

Treatment of advanced renal failure: low-protein diets or timely initiation of dialysis?

Until 1996, no guidelines existed for the initiation of dialysis in patients with progressive renal failure. The publication of the National Kidney Foundation-Dialysis Outcome Quality Initiative guidelines has generated a debate on the management of advanced renal failure and the role of low-protein diets (LPDs). We performed a review of the literature to identify articles on the initiation of dialysis and LPDs, particularly those since 1996. Delayed referral of patients is widespread in both the United States and Europe, and almost 25% of patients are started on dialysis at a glomerular filtration rate (GFR) of <5 mL/min/1.73 m2. There is a high prevalence of malnutrition at the time of first dialysis, which progressively improves upon initiation of dialysis. There is no evidence regarding the efficacy or safety of LPDs in nondiabetic patients younger than 70 years old [approximately 40% of U.S. incident end-stage renal disease (ESRD) patients] and in diabetics with GFR <25 mL/min/1.73 m2 (>40% of incident U.S. ESRD). In nondiabetics who are younger than 70 years old, adherence to LPD for four to five years can be estimated to result in a delay in dialysis by 6 to 11 months. However, suboptimal energy intake is widespread in advanced renal failure, which declines further upon institution of LPD. Even nutritionally sound patients develop subclinical nutritional decline despite intense counseling. There are no data on the efficacy or safety of LPD in subgroups that constitute approximately 80% of incident ESRD patients. Concerns still exist regarding their nutritional safety in the remainder. Initiation of dialysis results in improved nutritional status and should be considered in a timely fashion.

Cardiovascular and cerebrovascular morbidity and mortality among women with end-stage renal disease attributable to lupus nephritis

Cardiovascular and cerebrovascular diseases are common causes of morbidity and mortality in women with systemic lupus erythematosus (SLE) and are also common in patients with end-stage renal disease (ESRD). To determine whether women with ESRD caused by lupus nephritis are at greater risk for morbidity from these conditions than women with other causes of ESRD, data from the US Renal Data System were used to compare incidence rates of hospitalizations for acute myocardial infarction and cerebrovascular accident between women with ESRD caused by lupus nephritis and women with ESRD from other causes. The age- and race-adjusted incidences of hospitalizations for acute myocardial infarction during dialysis were 16.4 hospitalizations/1,000 patient-years among women with ESRD caused by lupus nephritis and 17.3 hospitalizations/1,000 patient-years among women in the comparison group (adjusted hazard ratio, 0.80; 95% confidence interval [CI], 0.58 to 1.08; P = 0.14). Adjusted incidence rates for acute myocardial infarction after renal transplantation also did not differ between these groups. Adjusted incidence rates for hospitalizations for cerebrovascular accident during dialysis were 18.5 hospitalizations/1,000 patient-years among women with ESRD caused by lupus nephritis and 19.2 hospitalizations/1,000 patient-years among women in the comparison group (adjusted hazard ratio, 0.87; 95% CI, 0.66 to 1.14; P = 0.30); incidence rates after transplantation also did not differ between groups. Risks for death from cardiovascular or cerebrovascular diseases also were not increased among women with ESRD caused by lupus nephritis. Sepsis was the most common cause of death in this group. Morbidity and mortality from acute myocardial infarction and cerebrovascular accident were substantially greater among women with ESRD caused by diabetes mellitus. Although morbidity and mortality from cardiovascular and cerebrovascular diseases are common among women with SLE, risks for these outcomes are not greater among women with ESRD caused by lupus nephritis than among other women without diabetes with ESRD.

Nutritional aspects in hemodialysis

The results of cross sectional studies throughout the world indicate that maintenance hemodialysis patients are at risk of malnutrition. Longitudinal studies show that malnutrition is associated with a reduced life expectancy mainly because of cardiovascular and infectious complications. Several factors are responsible for malnutrition of hemodialysis patients. Protein-energy intake is often reduced because of inappropriate dietary restrictions, anorexia, and taste alterations, promoting malnutrition in most patients entering dialysis. Intercurrent illnesses and frequent hospitalizations add to meal disturbances. A state of persistent catabolism may result from acidosis, resistance to anabolic factors such as growth hormone, insulin, and insulin-like growth factor-1, as well as a chronic inflammatory state caused by dialysis membrane and fluid bioincompatibility. In addition, losses of nutrients, including glucose, amino acids, proteins, and vitamins, occur during the dialysis treatment. Careful monitoring of dietary intakes is mandatory even in predialysis patients. In hemodialysis patients, the dose of dialysis should be adapted to correct acidosis and to relieve anorexia caused by accumulation of uremic toxins and hyperleptinemia. When malnutrition is established, active therapeutic interventions should take place, including intradialytic parenteral nutrition if oral supplementation has failed to improve nutritional status. Anabolism has been observed during the administration of recombinant growth hormone and insulin-like growth factor-1. Emerging therapeutic strategies against malnutrition may also involve a short period of daily dialysis.

Vitamin D deficiency is implicated in reduced serum albumin concentrations in patients with end-stage renal disease

The mortality rate in hemodialysis patients remains extremely high, and reduced serum albumin concentration resulting from malnutrition is the strongest predictor of mortality and morbidity. Several inflammatory cytokines involved in malnutrition, including interleukin-1, interleukin-6, and tumor necrosis factor-alpha, are modulated by 1,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)], of which synthesis is impaired in end-stage renal disease. We evaluated whether 1,25-(OH)(2)D(3) deficiency might be involved in reduced serum albumin concentrations. Fifty-one predialysis uremic patients about to begin hemodialysis therapy were divided into groups with serum 1,25-(OH)(2)D(3) concentrations less than 18 pg/mL (low-D(3) group; n = 39) and concentrations of 18 pg/mL or greater (normal-D(3) group; n = 12). Serum albumin concentrations before the initiation of hemodialysis treatment were compared between the two groups. Furthermore, the effect of supplementation with active forms of vitamin D during 4 months of hemodialysis treatment on serum albumin concentrations was retrospectively evaluated in the low-D(3) group. Serum albumin concentrations in the low-D(3) group were significantly less than those in the normal-D(3) group (3.58 +/- 0. 50 versus 3.82 +/- 0.10 g/dL; P = 0.034). Considering all patients, a significant positive correlation between serum concentrations of albumin and 1,25-(OH)(2)D(3) was noted (r = 0.417; P = 0.0023). Supplementation with active forms of vitamin D significantly increased serum albumin concentrations in the low-D(3) group from 3. 61 +/- 0.12 to 3.79 +/- 0.13 g/dL (P = 0.0067). These findings indicate that reductions in serum albumin concentrations may be attributed, at least in part, to vitamin D deficiency in patients with end-stage renal disease.

Venous thromboembolism in end-stage renal disease

Venous thromboembolic disease is considered an uncommon event in the end-stage renal disease (ESRD) population. We report five cases of venous thromboembolism (VTE) occurring in dialysis patients within a 1-year period at a single center. Analysis of these cases and review of the literature suggest that risk factors for VTE in the ESRD population are similar to those of the general population. Chronically ill, debilitated patients appear to be those most likely to develop VTE.

Natural history of arteriovenous grafts in hemodialysis patients

Most hemodialysis patients in the United States have an arteriovenous graft as their vascular access. Grafts have a relatively short life span and are prone to recurrent stenosis and thrombosis, requiring multiple salvage procedures to maintain their patency. There is little information in the literature regarding the clinical factors that determine graft survival and complications. We evaluated prospectively the outcomes of 256 grafts placed at a single institution during a 2-year period. A salvage procedure to maintain graft patency (thrombectomy, angioplasty, or surgical revision) was required in 29% of the grafts at 3 months, 52% at 6 months, 77% at 12 months, and 96% at 24 months. Thus, primary graft survival (time from graft placement to the first intervention) was only 23% at 1 year and 4% at 2 years. Primary graft survival was significantly less among patients with hypoalbuminemia compared with patients with a normal serum albumin level (P = 0.003). Secondary graft survival (time from graft placement to permanent graft failure) was 65% at 1 year and 51% at 2 years. Neither primary nor secondary graft survival was significantly correlated with patient age, sex, diabetic status, body mass index, or graft site. A mean of 1.22 interventions per graft-year were required to maintain access patency, including 0.51 thrombectomies, 0.54 angioplasties, and 0.17 surgical revisions. In conclusion, hypoalbuminemia is a strong predictor of the requirement for an early graft intervention. Patients with hypoalbuminemia may require a heightened index of suspicion in monitoring their grafts for evidence of stenosis.

Bacteremia associated with tunneled dialysis catheters: comparison of two treatment strategies

BACKGROUND

Tunneled dialysis catheters are often used for temporary vascular access in hemodialysis patients, but are complicated by frequent systemic infections. The treatment of bacteremia associated with infected tunneled catheters requires both antibiotic therapy and catheter replacement. We compared the outcomes of two treatment strategies for catheter-associated bacteremia: exchange of the existing catheter with a new one over a guidewire versus catheter removal with delayed replacement.

METHODS

We retrospectively analyzed the outcomes of all cases of tunneled dialysis catheter-associated bacteremia during a two-year period. The infection-free survival time of the subsequent catheter was evaluated in two groups of patients: group A (31 catheters), exchange of the existing infected catheter with a new catheter over a guidewire, and group B (38 catheters), removal of the infected catheter followed by delayed catheter replacement 3 to 10 days later. Patients in both groups received three weeks of systemic antibiotic therapy. Cox proportional hazard models were used to evaluate the factors predictive of infection-free survival time of the replacement catheter.

RESULTS

On univariate proportional hazard regression analysis, the infection-free survival time of the replacement catheter was similar for groups A and B (P = 0.72), whereas the hazard of infection was significantly greater for patients with hypoalbuminemia (serum albumin < 3.5 g/dL), as compared with patients with a normal serum albumin (hazard ratio 2.81, 95% CI, 1. 21, 6.53, P = 0.016). The infection-free survival time was not affected by patient age, sex, diabetic status, or type of organism (gram-positive coccus vs. gram-negative rod).

CONCLUSIONS

The infection-free survival time associated with the subsequent catheter is similar for the two treatment strategies. However, exchanging the catheter for a new one over a guidewire minimizes the number of separate procedures required by the patient. Hypoalbuminemia is the major risk factor for recurrent bacteremia in the replacement catheter.

Predictors of hospitalization and death among pre-dialysis patients: a retrospective cohort study

BACKGROUND

Although there is abundant research describing predictors of patient morbidity and mortality among dialysis patients, predictors of adverse clinical outcomes among pre-dialysis patients are less well defined. The purpose of this study was to identify baseline predictors of first non-elective hospitalization among a retrospective cohort of 362 pre-dialysis patients.

METHODS

Univariate and multivariate Cox proportional hazard models were used to identify predictors of hospitalization prior to dialysis initiation, adjusted for baseline creatinine level. Dialysis initiation, loss to follow-up, and study conclusion were censored events. Secondary outcomes included cause-specific hospitalization and death.

RESULTS

Univariate analysis indicated that advanced age (RR 1.026, CI 1.016-1.037), number of prescribed anti-hypertensive medications (RR 1.149, CI 1.019-1.296), history of myocardial infarction (RR 1.979, CI 1.339-2.926), congestive heart failure (RR 2.299, CI 1.616-3.270), angina (RR 2.289, CI 1.695-3.091), peripheral vascular disease (RR 1.841, CI 1.282-2.644), renal failure secondary to nephrosclerosis (RR 1.413, CI 1.033-1.933) or renal artery stenosis (RR 1.587, CI 1.036-2.430), lower baseline haemoglobin level (RR 0.986, CI 0.979-0.992), and baseline creatinine greater than 300 micromol/l (RR 1.636, CI 1.233-2.171) were predictors of hospitalization. Gender, diabetes, diastolic blood pressure, mean arterial pressure, history of stroke, and hypoalbuminaemia did not predict outcome. Multivariate analysis, adjusted for baseline creatinine level, selected advanced age (RR 1. 017, CI 1.006-1.027), angina (RR 1.893, CI 1.371-2.613), peripheral vascular disease (RR 1.545, CI 1.054-2.266), and haemoglobin level (RR 0.987, CI 0.944-0.979) as independent predictors of hospitalization.

CONCLUSION

Advanced age, co-morbid cardiovascular illness and anaemia are independent predictors of non-elective hospitalization prior to dialysis initiation. Further study is needed to determine the extent to which aggressive pre-dialysis management of anaemia and cardiovascular disease can improve patient outcomes.

Effect of biocompatibility of hemodialysis membranes on serum albumin levels

Hypoalbuminemia in end-stage renal disease is a marker of high morbidity and mortality. In some patients, the cause of low serum albumin levels is easily identified and therefore treatable, but in many patients, the cause is not clear. We studied the effect of changing the dialysis membrane from a bioincompatible to a biocompatible membrane on serum albumin level. Stable hemodialysis patients dialyzed with cuprammonium membranes who had serum albumin levels less than 3.5 g/dL were switched to the more biocompatible membrane, polysulfone. Serum albumin levels increased from 3.22 +/- 0.037 to 3.35 +/- 0.038 g/dL (mean +/- SE; P < 0.002). The increase was seen in patients both with and without diabetes. Thus, dialyzer membrane may affect serum albumin levels and should be considered in the differential diagnosis of hypoalbuminemia in patients undergoing hemodialysis with bioincompatible membranes. Membrane choice may have an important effect on the outcome of morbidity and mortality of hemodialysis patients.

Description of a new surveillance system for bloodstream and vascular access infections in outpatient hemodialysis centers

Bloodstream and vascular access infections are a threat to hemodialysis patients. However, there are few studies of rates of such infections and there are no standardized methods for ongoing data collection. Because of frequent hospitalizations and receipt of antimicrobials, hemodialysis patients are at high risk for infection with drug-resistant bacteria. This article describes a new voluntary national surveillance system. Each month participating dialysis center personnel will record the number of chronic hemodialysis patients that they treat (broken down into four types of vascular access). A one-page form will be completed for each hospitalization or in-unit IV antimicrobial start among these patients. These data will allow calculation, stratified by type of vascular access, of several rates, including hospitalizations, in-unit IV antimicrobial starts, and vascular access infections. For individual dialysis centers, this surveillance system will provide a simple and standardized method for recording data, calculating rates, and comparing rates over time. It is hoped that collection and examination of these data will lead to quality improvement measures. For government and the medical and public health communities, aggregation of these data from many dialysis centers will provide a wealth of information that is not currently available. For further information, or to receive a protocol for this study, contact Elaine R. Miller, RN, MPH, at (404)639-6422 (telephone), (404)639-6459 or 6458 (fax), or erm4@cdc.gov (e-mail:). Information is also available on the CDC website at http:@www.cdc.gov/ncidod/hip/Dialysis/dialysis.+ ++htm.

Validation of comorbid conditions on the end-stage renal disease medical evidence report: the CHOICE study. Choices for Healthy Outcomes in Caring for ESRD

Since 1995, the Medical Evidence Report for end-stage renal disease (Form 2728) has been used nationally to collect information on comorbid conditions. To date, these data have not been validated. A national cross-sectional study of 1005 incident dialysis patients (734 hemodialysis and 271 peritoneal dialysis) enrolled between October 1995 and June 1998 was conducted using clinical data to validate 17 comorbid conditions on Form 2728. Sensitivity and specificity were calculated for each condition. The relationship between patient characteristics and sensitivity was assessed in multivariate analysis. Sensitivity was fairly high (0.67 to 0.83) for HIV disease, diabetes, and hypertension; intermediate (0.40 to 0.52) for peripheral vascular disease, neoplasm, myocardial infarction, cerebrovascular disease, coronary artery disease, cardiac arrest, and congestive heart failure; and poor (<0.36) for dysrhythmia, ambulation status, pericarditis, chronic obstructive pulmonary disease, and smoking. Sensitivity did not change significantly over calendar time. The sensitivity of Form 2728 averaged across all 17 conditions was 0.59 (95% confidence interval, 0.43 to 0.75). The average sensitivity was 0.10 greater in peritoneal dialysis than hemodialysis patients. 0.11 greater in diabetic patients than nondiabetic patients, and 0.04 less with each added comorbid condition. The specificity was very good for hypertension (0.91) and excellent (>0.95) for the other 16 conditions. Comorbid conditions are significantly underreported on Form 2728, but diagnoses are not falsely attributed to patients. Scientific research, quality of care comparisons, and payment policies that use Form 2728 data should take into account these limitations. Considerable effort should be expended to improve Form 2728 coding if it is to provide accurate estimates of total disease burden in end-stage renal disease patients.

Amino acid losses during hemodialysis with polyacrylonitrile membranes: effect of intradialytic amino acid supplementation on plasma amino acid concentrations and nutritional variables in nondiabetic patients

BACKGROUND

Malnutrition is highly prevalent in hemodialysis patients. Amino acid (AA) losses during the dialysis procedure may be a contributing factor.

OBJECTIVES

The objectives of this study were 1) to prospectively evaluate AA losses and their effect on plasma AA concentrations during dialysis with polyacrylonitrile at baseline and after administration of AAs by intradialysis and 2) to investigate the effects of intradialytic AA supplementation on nutritional status.

DESIGN

Seventeen stable patients without diabetes who were receiving hemodialysis were studied. In the first phase, AA losses were evaluated over 2 wk in 10 patients randomly assigned to receive AA supplementation. AA losses were analyzed during the first week without supplementation and during the second week with AA administration. In the second phase, the patients' nutritional status was investigated after 3 mo of AA supplementation and was compared with those in 7 patients not receiving AAs.

RESULTS

Mean +/- SD) AA losses during a 4-h dialysis session were 12 +/- 2 g; there was a significant decrease in plasma AA concentrations (386 +/- 298 micromol/L for essential and 902 +/- 735 micromol/L for nonessential AAs). After administration of AAs, the losses increased to 28 +/- 4 g. However, this procedure produced a positive net balance of AAs (10.6 +/- 5.6 g for total AAs), preventing a reduction in plasma concentrations. After 3 mo of AA administration, there was a significant increase in protein catabolic rate and serum albumin and transferrin. This improvement occurred without any change in the dialysis dose, ruling out the possibility that an increase in dialysis efficiency played a role.

CONCLUSIONS

Intradialysis adequately provides AA supplements, prevents reductions in plasma AA concentrations, and favorably affects the nutritional status of patients receiving hemodialysis.

Septicemia in diabetic hemodialysis patients: comparison of incidence, risk factors, and mortality with nondiabetic hemodialysis patients

Diabetes mellitus is the most common cause of treated end-stage renal disease (ESRD), and diabetic hemodialysis patients have a high mortality rate. To identify differences in risk of septicemia among diabetic and nondiabetic hemodialysis patients, we examined the incidence, risk factors, and mortality for septicemia in a large sample of the US hemodialysis population. We performed a longitudinal cohort study of the incidence and risk factors for hospitalized cases of septicemia in diabetic and nondiabetic hemodialysis patients using baseline data from the US Renal Data System case-mix severity study with 7-year follow-up from hospitalization and death records. Independent risk factors for septicemia were assessed using Poisson regression. Independent effect of septicemia on mortality was assessed using Cox proportional hazards analysis. Over 7 years, 11.1% of nondiabetic patients and 12.5% of diabetic patients experienced at least one episode of septicemia. Older age and low serum albumin were independent risk factors for septicemia in all patients. In diabetics, white race, peripheral vascular disease, and hemodialyzer reuse, particularly in type 1, were independent risk factors. In nondiabetics, coronary artery disease, cerebrovascular disease, and temporary and permanent catheters were associated with an increased risk. In both groups, patients who experienced an episode of septicemia had twice the risk of death from any cause and an eightfold risk of death from septicemia. Septicemia occurs equally frequently and carries a marked increased risk of death in both nondiabetic and diabetic hemodialysis patients. Improving nutritional status and minimizing the use of catheters might help ameliorate the risk of septicemia. In diabetics, aggressive treatment of peripheral vascular disease might help reduce the risk of septicemia. Further research to elucidate potential mechanisms for variations in risk for septicemia according to race and hemodialyzer reuse practices are warranted in diabetic patients.

Determinants of type and timing of initial permanent hemodialysis vascular access

BACKGROUND

We undertook a population-based study of hemodialysis (HD) patients to determine which factors are important in predicting the type of permanent access initially placed and if a functional permanent access is in place at the start of HD.

METHODS

Selected characteristics were abstracted from the United States Renal Data System (USRDS) Dialysis Morbidity and Mortality Study (DMMS) Wave 2. Logistic regression was used to estimate the independent contribution of specific characteristics in predicting whether the initial permanent access placed was an arteriovenous (AV) fistula compared with a polytetrafluoroethylene (PTFE) graft, and in predicting whether permanent access (fistula or graft) was in place at the initiation of dialysis.

RESULTS

Sixty-seven percent of the patients had an AV graft placed as their first permanent access. Characteristics important in predicting if a fistula was initially placed included age (per decade; aOR = 0.84, P < 0.001), female gender (aOR = 0.52, P < 0.001), body mass index (per standard deviation; aOR = 0.70, P = 0.09), avoiding blood draws (aOR = 1.96, P < 0.001), ability to ambulate (aOR = 2.24, P = 0.008), underlying renal disease (glomerular compared with diabetes, aOR = 2.19, P = 0.009), college education (aOR = 1.72, P = 0.002), and sharing in decision making (aOR = 1.50, P = 0.02). Thirty-four percent of patients (34.4%) had functional permanent access at the start of HD. Characteristics important in predicting which patients had functional permanent access included serum albumin (per 1 mg/dL increase, aOR =1.55, P = 0.003), erythropoietin prior to starting HD (aOR = 1.79, P = 0.002), fewer predialysis nephrologist visits (aOR = 0.21, P < 0.001), and when the patient was told they had renal disease (aOR = 0.33, P = 0.002).

CONCLUSIONS

PTFE grafts were the most common initial permanent access. The majority of patients did not have permanent access at the start of dialysis. Factors that are thought to compromise identification of adequate veins were important predictors of PTFE graft placement. Permanent access at the start of HD was largely a function of early patient education and early referral to a nephrologist.

Protein-energy malnutrition as a risk factor for increased morbidity in long-term hemodialysis patients

This prospective nonintervention single-center study was undertaken to investigate the role of protein-energy malnutrition (PEM) as a risk factor for morbidity in patients on long-term hemodialysis. Thirty-seven patients from the renal unit of Tygerberg Hospital, Tygerberg, South Africa, were studied for a mean period of 26 months. Morbidity was the main outcome and was defined as the number of hospitalizations and days of hospitalization per patient per year. Investigations included 4-monthly determinations of interdialytic protein catabolic rate (PCR), dietary intake of protein and energy, blood levels of albumin and urea, lymphocyte count, adequacy of dialysis (Kt/V), body weight, intradialytic weight loss, fat mass (FM), fat-free mass (FFM), body mass index (BMI), and bone-free arm muscle area (BF-AMA). A PEM composite score was derived from postdialysis serum albumin, BF-AMA, FM, FFM, and BMI. All-cause morbidity as defined by number of hospitalizations (see text for other definitions of morbidity) showed a significant correlation with the mean and baseline PEM score (P <.01), and a negative correlation with predialysis and postdialysis serum albumin (P <.05) and age (P <.05). There was no significant relationship with PCR, percentage intradialytic weight loss, Kt/V, reuse of dialyzer, period on maintenance hemodialysis, sex, race, and type of dialyzer membrane. When "only infection-related" morbidity was considered, the factors that showed a significant correlation were the mean (P <. 001) and baseline PEM score (P <.01), and percentage intradialytic weight loss (P <.01). There was no significant deterioration in the nutritional status of patients followed up for at least 24 months. It is concluded that infection-related morbidity was associated most strongly with the PEM score and the percentage intradialytic weight loss. The results suggest that PEM is one of the important contributing factors to morbidity, possibly via an effect on the immune system and infection.