Long-term outcomes of peritoneal dialysis.
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Biomedical subjects
Publications and source records attributed to G Brunori.
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The choice of a dialysis treatment depends on many factors, both medical and non-medical. A full and rational treatment requires easy access to a transplantation programme and to all dialysis modalities, extracorporeal or peritoneal. Presently, haemodialysis (HD) is used almost exclusively for in-centre or limited care treatment, peritoneal dialysis (PD) being preferred for home treatment. On HD, bicarbonate buffer is used in preference to acetate. Mixed convective-diffusive HD techniques have a very limited utilization world-wide because of their cost. Use of PD and automated PD continues to grow, although slowly. In our single-centre experience on a large number of patients, 10-year patient survival is not different on CAPD and HD, and there is initial lower risk of death on CAPD for patients > or = 75 years of age. Drop-out from CAPD has increased in recent years, mainly due to the patient/partner 'burn-out'. Drop-out is less for the elderly, and the difference in modality change between CAPD and HD decreases with increasing patient age, suggesting a clear indication for CAPD in the elderly, or in adults waiting for a transplant. The clinical background, e.g. the presence of diabetes mellitus, cardiovascular disease, dyslipidaemia or obesity, is also important in the choice of method.
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We have reviewed the literature and our own center's results for patients on long-term continuous ambulatory peritoneal dialysis (CAPD) in comparison to results for patients on hemodialysis (HD). Contrary to recent American data showing one-year survivals to be worse on CAPD, the Canadian Registry and other studies show no significant difference in survivals on the two methods. Results are also conflicting for diabetics. Insufficient adjustments for age and case-mix variations are probably the most important causes for differences. For the general population, personal Cox-adjusted data show no difference between CAPD and HD up to ten-year follow-up, with very close curves for the adults and non-significant differences for the elderly. Old elderly (> 75 years) have better survival on CAPD in the first years of treatment. Dropout, which is higher on CAPD, decreases with age, and the patient retention on CAPD is worse than on HD for all patients, except the old elderly, for whom it is similar. These data were obtained in patients receiving a standard treatment, modified in order to give a more adequate dialysis dose only in recent years. The results of a prospective three-year study on the effect of nutritional [serum albumin and transferrin, normalized protein catabolic rate (PCRN), and subjective global assessment of malnutrition] and adequacy indices [Kt/V, creatinine clearance (Ccr), residual renal function] on patient survival on CAPD and HD are reported. Survival was not different for the two methods. Using the Cox analysis, nutritional indices did not affect survival whereas adequacy indices did. The effect of low serum albumin on survival was referable to the predialysis nutritional state. The similar survivals obtained on CAPD and HD, with Kt/V more or less than 1.0/treatment for HD and 1.7/week for CAPD, support the "peak concentration hypothesis" of Keshaviah et al. Survival in different groups of patients with different Kt/V and Ccr shows that the adequate dose on CAPD is Kt/V between 1.96 and 2.03 and Ccr > or = 70 L/week. A group of 26 patients who remained on CAPD treatment for more than eight years was also studied. Patient age and predialysis comorbidity were the most important factors affecting survival. Patients surviving longest had > 3 g/dL of serum albumin, > 0.8 g/kg/day of PCRN, a Kt/V > 1.6, and a weekly Ccr > 54L/week.
Although malnutrition is not uncommon in continuous ambulatory peritoneal dialysis (CAPD) and maintenance hemodialysis (MHD) patients, there has never been a large-scale comparison study of nutritional status with these two dialysis modalities. We therefore assessed protein-calorie nutrition in 224 CAPD patients and 263 MHD patients who were treated in eight centers in Italy. The CAPD patients were slightly older than the MHD patients (60.2 +/- 14.2 years v 56.3 +/- 15.1 years; P < 0.01), had undergone dialysis for less time (2.32 +/- 2.10 years v 3.66 +/- 2.66 years; P < 0.0001), and had higher residual renal function (1.83 +/- 2.29 mL/min v 0.27 +/- 0.91 mL/min; P < 0.0001). Protein nitrogen appearance was 60.5 +/- 16.6 g/d and 61.9 +/- 16.5 g/d in the CAPD and MHD patients, respectively. In CAPD versus MHD patients, serum total protein and albumin tended to be lower; serum transferrin and midarm muscle circumference were similar; and relative body weight, skinfold thickness, and estimated percent body fat tended to be greater. These greater values in CAPD patients were particularly evident in those who were 65 years of age or older. Serum glucose, total cholesterol, and triglycerides also were greater in CAPD patients. The subjective global nutritional assessment indicated a significantly greater proportion of malnourished CAPD patients than MHD patients (42.3% v 30.8%). The greater prevalence of malnutrition in CAPD patients diminished with age. Maintenance hemodialysis patients older than 76 years were more likely to be malnourished than CAPD patients. In patients less than 65 years of age, protein-calorie malnutrition was more likely to be present in CAPD patients than in MHD patients.
Nineteen malnourished chronic peritoneal dialysis patients who were ingesting a low protein intake underwent metabolic balance studies to test whether a dialysate that contained amino acids would improve their protein nutrition. Patients lived in the hospital for 35 days while they ate a constant diet and underwent their usual regimen of continuous ambulatory peritoneal dialysis (CAPD). The first 15 days served as a Baseline Phase. For the last 20 days, the usual dialysate was substituted with a dialysate of essentially the same composition except that it contained 1.1% essential and nonessential amino acids and no glucose. Patients received one or two dialysate exchanges with amino acids each day depending on the amount necessary to bring the individual's dietary protein plus dialysate amino acid intake to 1.1 to 1.3 g/kg body weight/day. During Baseline, patients were in neutral nitrogen balance; net protein anabolism was positive, as determined from 15N-glycine studies. After commencing intraperitoneal amino acid therapy, nitrogen balance became significantly positive, there was a significant increase in net protein anabolism, the fasting morning plasma amino acid pattern became more normal, and serum total protein and transferrin concentrations rose. Patients generally tolerated the treatment well, although some patients developed mild metabolic acidemia. These findings indicate that a dialysate containing amino acids may improve protein malnutrition in CAPD patients ingesting low protein intakes.
BACKGROUND: The effects of dialysis inadequacy on patient survival and nutritional status and that of malnutrition on survival have not been clearly assessed. Studies comparing dose/mortality and morbidity curves on continuous ambulatory peritoneal dialysis (CAPD) and on haemodialysis (HD) are also needed, to assess adequate treatment on CAPD. METHODS: We have evaluated the effects of age, 13 pretreatment risk factors, serum albumin, transferrin, normalized protein catabolic rate, Kt/V, normalized weekly creatinine clearance, residual renal function and subjective global assessment of nutritional status on survival and morbidity, in a 3-year prospective study of 68 CAPD and 34 HD patients. RESULTS: Survivals did not differ for CAPD and HD patients. In the Cox hazard regression model, age, peripheral vasculopathy, serum albumin < 3.5 g/dl and Kt/V < 1.0/treatment on HD and < 1.7/week on CAPD were independent factors negatively affecting survival. On the contrary, adjusted survivals were not affected by gender, modality, other comorbid factors, normalized protein catabolic rate, or subjective global assessment of nutritional status. Persistence of residual renal function significantly improved survival. Observed and adjusted survival did not significantly differ for CAPD and HD patients with either low (HD, < 1.0/treatment; CAPD, < 1.7/week) or high ( > or = 1.0 and > or = 1.7) Kt/V. On HD, adjusted survivals were similar for 1.0 < or = Kt/V < 1.2 or > or = 1.2. On CAPD, Kt/V > or = 1.96/week was associated with definitely better survival, with only one death/23 patients versus 19/45, with Kt/V < or = 1.96. Survival was not different for 1.96 < or = Kt/V < 2.03 and > or = 2.03. Normalized weekly creatinine clearance and wKt/V were positively related on CAPD (r 0.39, P < 0.01) and wKt/V = 1.96 corresponded to 58 litres of normalized weekly creatinine clearance. CONCLUSIONS: Indices of adequacy were predictors of mortality and morbidity, both on CAPD and HD, whereas normalized protein catabolic rate and subjective global assessment of nutritional status were not. Serum albumin did not decrease during dialysis; hence its predictive effect for survival is due to the predialysis condition and not to dialysis-induced malnutrition.
It has been recently reported that elderly chronic haemodialysis (CHD) patients have a reduced protein catabolic rate (PCRn) in spite of an adequate Kt/V. However until now the long-term consequences of this fact on the nutritional status, morbidity, and mortality were not known. This prospective study evaluates, over a period of 3 years, the effect of the reduced PCRn on some nutritional parameters, morbidity mortality in CHD patients older than 65 years with adequate and stable Kt/V. Over the period 1990-1993 we evaluated 42 CHD patients over 65 years (mean +/- SD 72 +/- 5 years). PCRn, total serum proteins, serum albumin concentration, body weight, body mass index (BMI) and serum transferrin were determined at the start of the study and followed yearly until the end of observation. The incidence of hospitalization/patient-year, the mortality rate and the causes of death were also recorded. All the patients were managed to maintain a Kt/V > 0.9 throughout the study. Twenty-two patients (Group A), mean age 70 +/- 4 years, completed the entire period of observation. Their Kt/V was 1.10 +/- 0.12, PCRn was 0.95 +/- 0.12 g/kg/day, and serum albumin concentration was 40.2 +/- 1.5 g/l, and these did not change significantly. The other parameters also remained stable over time. Twenty patients (Group B) died. Their mean age was 74 +/- 6 years. This group's Kt/V was 1.11 +/- 0.15, PCRn was 0.94 +/- 0.18 g/kg/day, and serum albumin concentration was 39 +/- 3.1 g/l, and there were no significant variations between the start and the end of observation for all the parameters studied.(ABSTRACT TRUNCATED AT 250 WORDS)
An increasing number of elderly patients with uraemia are treated by dialysis therapy. Virtually every published study on nutritional status of patients undergoing maintenance haemodialysis treatment or continuous ambulatory peritoneal dialysis (CAPD) has indicated that a substantial proportion of patients undergoing regular dialysis treatment have protein calorie malnutrition. Problems of undernutrition increase significantly with age; a combination of socioeconomic, psychological, and biochemical problems interfering with acquiring and assimilating a balanced diet are responsible for nutritional deficiencies in older people. We assessed the prevalence of protein calorie malnutrition in 183 regular dialysis patients aged 65 years or older treated with haemodialysis or CAPD. This group of patients was compared to two other groups aged 18-40 years (62 patients) and 41-64 years (239 patients). Presence of malnutrition was assessed by selected serum chemistries, anthropometry and Subjective Global Nutritional Assessment. Adequacy of dialysis, protein nitrogen appearance, as an index of protein intake, and residual renal function were measured. The results indicate that protein calorie malnutrition occurs commonly in regular dialysis patients, with a higher prevalence of malnutrition in the elderly; 51% of patients of the elderly group were classified as malnourished, and no difference was found with the two dialytic modalities.
On 578 unselected new patients followed from 1981 through 1993, 51% on CAPD and 49% on HD, long-term patient and method survivals, cause of death, and drop-out in the two methods were compared. Survival, adjusted for patient selection biases, was not different on CAPD and HD up to 10 years. 50% of the patients were still in their first treatment after 3.5 years on CAPD and after 7 years on HD, and 5 and 28% respectively, after 10 years. Patient survival on CAPD was not falsely improved by drop-outs. Drop-out is increasing for CAPD, mainly due to patient/partner burn-out, which should be relieved by a more liberal application of automated PD. Malnutrition is more frequent on CAPD than on HD but not for the elderly. In a 3 year prospective study on 60 CAPD and 34 HD patients serum albumin, nPCR and nutritional status, as assessed by SGA did not influence survival in each modality. Survival was similar with K(p,r)t/V > or = 1.7/week on CAPD and Kt/V > or = 1/treatment on HD, and worse below these values. On CAPD, a Kp,rt/V > or = 1.96 gave better survivals.
Peritonitis is a crucial complication of peritoneal dialysis. Over the last few years, new device systems have been developed to reduce episodes of peritonitis caused by exogenous contamination. Remarkable improvement has been obtained by modifying the original connection between the catheter and the bag with the introduction of the Y-set. The aims of this study were to test the reliability and simple use of a double-bag system without disinfectant in-line (Gemini, Gambro) and to evaluate the incidence of peritonitis in a 2-year period of follow-up. In a group of 167 patients, enrolled in 14 dialysis units in Italy, with a follow-up of 2433 patient-months, we observed 82 episodes of peritonitis in 52 patients, with a cumulative incidence of 1 episode every 29.7 patient-months. At 12 months the percentage of patients peritonitis-free was 69.7%, and at 24 months it was 62.8%. The training to complete the bag exchange, assessed by patient and nursing staff, was defined as "easy" in 61% of the cases and "difficult" in only 12% of the cases. The percentage of patients requiring a partner was 23%. For patients this device system presents easy handling in terms of the bag exchange, and it may prevent peritonitis.
Peritonitis is still one of the most important complications of peritoneal dialysis. Over the last few years, many efforts have been made in developing new device systems. A remarkable improvement has been obtained by modifying the original connection between the catheter and the bag, especially after the introduction of the Y-set. The aim of this study was to verify whether the use of a new device system, called the T-set, could reduce the incidence of peritonitis. This connector adds the advantages of the Y-set to those of the twin bag. In a group of 53 patients enrolled in a three-year period with a follow-up of 797 patient-months, we observed an incidence of peritonitis of one episode every 50 months. Furthermore, in the subgroup of 39 new patients, we observed an incidence of peritonitis of one episode every 89 patient-months. This new device can be a further step in the evolution of connectors that reduce the incidence of peritonitis.
The aim of this study was to verify whether the replacement of the peritoneal catheter in a single operation and during infectious complications of peritoneal dialysis is effective and safe. Sixty-eight infectious complications refractory to appropriate antibiotic therapy were treated by this technique: 26 tunnel infections, 22 peritonitis-complicating tunnel infections, 12 refractory peritonitis, and 8 recurrent peritonitis. Operations were successful in all cases of tunnel infection and recurring peritonitis, and in all cases but one of peritonitis-complicating tunnel infection. Ten failures occurred among the 12 catheters removed for refractory peritonitis. Microorganisms cultured in these 10 failures were: Fungi (3 cases), Mycobacterium (2 cases), Pseudomonas (2 cases), Acinetobacter (1 case), Acinetobacter+Pseudomonas (1 case), and Enterococcus (1 case). Complications were 3 one-way obstructions and 2 external dialysate leaks. This study supports the simultaneous catheter replacement-removal procedure during infectious complications of peritoneal dialysis (PD) with the exception of refractory peritonitis; this technique spares the patient the temporary vascular access, the shift to hemodialysis, and a second operation to insert a new catheter. There are few complications.
Acute and chronic studies in rats have shown that administration of human recombinant insulin-like growth factor I (rhIGF-I) lowers renal vascular resistance and increases RPF, GFR and proximal tubular phosphate absorption. In the present study we examined the effects of subcutaneous injections of rhIGF-I on glomerular and tubular function in eight normal men. Individuals were studied for 5.5 consecutive days in a clinical research center while they ate a constant diet. Four subjects were studied in a non-volume expanded state (Group 1) and four individuals were evaluated during a saline load. From the second to the fourth day, subjects received subcutaneous injections of rhIGF-I, 60 micrograms/kg, at 0800, 1400 and 2000 hours. After commencing the rhIGF-I injections, serum IGF-I levels rose quickly and remained at about three to four times that of baseline throughout the period of rhIGF-I injections. In both the normal and the saline loaded subjects, renal vascular resistance decreased and RPF and GFR (PAH and inulin clearances) rose quickly and were clearly altered within six hours after starting the rhIGF-I injections. RPF had increased by 32 +/- 3% and 33 +/- 2% (grand mean +/- SEM) in the normal and the saline loaded subjects, and GFR rose by 22 +/- 3% and 36 +/- 4% in the two groups. In both groups the absolute and the fractional excretion of phosphate decreased markedly during rhIGF-I treatment, but the absolute and fractional excretion of calcium did not change. The urinary fractional and absolute excretion of albumin and IgG also increased, although slightly, with rhIGF-I injections. There was no consistent effect of IGF-I on tubular sodium handling. These findings demonstrate that in normal men subcutaneous injections of rhIGF-I greatly increase RPF, GFR, and tubular phosphorus reabsorption and enhances microproteinuria.
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We have reappraised studies on morbidity and mortality in continuous ambulatory peritoneal dialysis (CAPD), comparing it with hemodialysis (HD), the standard treatment for end-stage renal disease (ESRD). More hospitalization is required for CAPD, the difference being related to peritonitis, to the more frequent presence of some risk factors (such as diabetes and atherosclerosis) in the patients selected for CAPD, and to the lack of experience in the early years of CAPD practice. CAPD patients have less acute morbidity during treatment that not always requires hospitalization: hypotension, hypertension, arrhythmias, and myocardial ischemia. Cardiac performance is also better in CAPD patients, who develop less myocardial hypertrophy than HD patients. Hospitalization due to infectious disease not referable to technique, beta 2-microglobulin related morbidity, signs of uremic neuropathy, osteodystrophy, and malnutrition are similar in both groups. Method survival is better for HD, the difference being completely accounted for by peritonitis. Patient survival adjusted for pre-treatment differences is similar in CAPD and HD, and this is not an artifact of more drop-outs on CAPD. A high incidence of peritonitis is accompanied by an increased risk of death. Older patients have a lesser risk of death on CAPD than on HD. Diabetics have a worse survival than non-diabetics, with no difference between the two methods. Although patient survivals on CAPD and HD are the same, differences in the mode of blood purification have an interesting impact on particular aspects of morbidity.
We studied morbidity in 648 patients treated in our center in a ten-year period as indicated by duration of hospitalization: 232 patients were on CAPD, 188 on hemodialysis (HD) and 228 had cadaveric kidney transplants (Tx). Duration of hospitalization was divided into four groups according to its causes. The age of the patients on CAPD was 61 +/- 14 years, 53 +/- 17 on HD and 36 +/- 10 in the Tx group. The total follow-up was 629 patient-year (p-y) on CAPD, 458 p-y on HD and 928 p-y on Tx. The first admission was longer on CAPD (30 +/- 18 days) and on Tx (36 +/- 18 days) than on HD (18 +/- 12). After the first admission, the total days of hospitalization (days/patient-year, d/p-y) were more for CAPD than HD and Tx. Analysis of these data showed that the difference was due to peritonitis and to the different percentage of elderly patients in the CAPD group. With a reduction in the incidence of infectious complications (peritonitis, tunnel or exit-site), hospitalization in CAPD could be reduced to a length of time similar to that currently needed by HD and Tx patients. This can result in important cost-saving.
We studied normalized urea nitrogen appearance (NUNA), normalized protein catabolic rate (NPCR), and normalized daily creatinine excretion (NDCE) in twenty-one patients (15 men, 6 women; mean age 63 +/- 9 years) on CAPD for more than 4 years (80 +/- 27 months). In the same patients we evaluated the changes in serum albumin and transferrin with time. After 74 +/- 26 months on CAPD, NUNA was 0.12 +/- 0.03 g/Kg IBW/day, NPCR = 1.09 +/- 0.19 g/Kg IBW/day; NDCE = 15.1 +/- 3.1 mg/Kg IBW/day; serum albumin = 3.8 +/- 0.2 g/dl. NUNA was correlated with NPCR (p < 0.001) and both were correlated with NDCE (p = 0.007 and p = 0.008). NPCR significantly decreased as patient age increased (p = 0.007) but was not correlated with time on CAPD, sex or serum albumin. Serum albumin did not change as age increased. Serum albumin and serum transferrin had not significantly changed after 4 years (after 8 years in a subgroup of eight patients). Finally, we compared these data to the initial data recorded for the same patients (mean interval: 64 +/- 21 months). NUNA, NPCR and NDCE did not change significantly. Changes in NPCR were directly related to changes in NDCE (p = 0.019). This study supports that long-term CAPD does not necessarily impair nutritional status and suggests that the oldest patients can maintain stable serum albumin concentrations on lower protein intake than younger ones.