Body Composition Analysis of Patients on Waiting List for Cadaveric Renal Transplantation: A Comparison of Hemodialysis and Peritoneal Dialysis Patients Z. Bal, M.E. Uyar, E. Tutal, O. Guliyev, S. Sezer, and M. Haberal ABSTRACT Background. Bioelectrical impedance analysis is a simple, noninvasive method of assessing body composition. Dialysis modality and selection of buffer type may have an impact on body composition. The aim of our study was to compare body compositions of patients from the waiting list for cadaveric renal transplantation according to the dialysis modality. Methods. We examined a total of 152 (110 hemodialysis [HD] and 42 continuous ambulatory peritoneal dialysis [CAPD]) patients. Demographic data were collected from patient charts. The last 6 months routine laboratory evaluations including hemoglobin, serum creatinine, intact parathyroid hormone, albumin, C reactive protein, calcium, phosphorus were collected. Body compositions were measured using the Tanita BC420MA Body Composition Analyzer (Tanita, Tokyo, Japan). We made a subanalysis of the CAPD group according to buffer choices as follows: lactate-buffered (n ¼ 16) and bicarbonate/lactateebuffered (n ¼ 26) solution users. Results. The body weight (P ¼ .022), body mass index (BMI; 25.8 4.7 vs 23.4 4.9 kg/m2, P ¼ .009), muscle mass (P ¼ .01), fat-free mass (P ¼ .013), and visceral fat ratio (9.5 5.4 vs 7.3 4.1 %, P ¼ .022) were significantly higher in the CAPD group. Total body water of CAPD patients were also higher (P ¼ .003), but total body water ratios of HD and CAPD groups were similar. Fat and fat-free mass ratios of patient groups were also similar. Comparing CAPD subgroups we observed that patients using bicarbonate/ lactateebuffered solutions had higher body weights (P ¼ .038), BMI (27.1 5 vs 23.7 3.5 kg/m2, P ¼ .018) values, and visceral fat ratios (8.0 5.2 vs 4.6 2.5 %, P ¼ .023). These patients also tend to have higher fat mass without statistical significance (P ¼ .074). Fat, muscle, and fat-free mass total body water ratios of peritoneal dialysis subgroups were similar. Conclusion. We believe that body composition analysis should be used as a complementary method for assessing nutritional status of PD and CAPD patients as body weight or BMI measurements do not reflect fat, muscle masses, and visceral fat ratios in these patients. Stable, well nourished CAPD patients should be closely observed and be encouraged to increase daily exercise and/or decrease calorie intake from other sources to decrease risks associated with abdominal obesity.
B
ODY MASS consists of fat mass and fat-free mass (lean mass). Lean mass can serve as an index of muscle mass and somatic protein storage, whereas fat mass more directly reflects energy storage. Notably, there is a progressive decline of lean body mass in chronic kidney disease (CKD) patients indicating ongoing catabolism.1e3 Interestingly, fat mass (or a better body fat distribution) may be
From the Departments of Nephrology (Z.B., M.E.U., E.T., O.G., S.S.) and General Surgery (M.H.), Baskent University Faculty of Medicine, Ankara, Turkey. Address reprint requests to Emre Tutal, Associate Professor, Department of Nephrology, Baskent University Faculty of Medicine, Besevler, Ankara, 06490, Turkey. E-mail: emretutal@gmail. com
ª 2013 Published by Elsevier Inc. 360 Park Avenue South, New York, NY 10010-1710
0041-1345/13/$esee front matter http://dx.doi.org/10.1016/j.transproceed.2013.08.097
Transplantation Proceedings, 45, 3489e3493 (2013)
3489
3490
protective rather than deleterious in maintenance dialysis, and a reduction in fat mass over time seems to be associated with poor survival.4,5 Bioelectrical impedance analysis (BIA) has significant potential as a complementary method to standard anthropometric techniques in the nutritional monitoring of CKD patients. BIA is a practical bedside tool for assessment of body composition that provides more consistent and reproducible results than standard anthropometry alone.6 Recent studies have reported better survival rates in overweight and obese hemodialysis (HD) patients. This is known as paradoxical obesity or reverse epidemiology.4 Additionally, atherosclerosis often coexists with a low body mass index (BMI) and a low serum albumin level, two factors that are well known predictors of poor survival in HD patients.2 Peritoneal dialysis (PD) offers potential advantages compared with HD including continuous calorie supply by glucose containing dialysate usage, avoiding the catabolic stimuli of foreign material, and having less restrictions for dietary and fluid intake. In this sense, it has already been proven that pure bicarbonate-buffered PD solutions have better success in correcting metabolic acidosis.7,8 However, PD patients have their own risk of protein malnutrition because high calorie intake and abdominal discomfort might cause decreased oral intake. In the present study, we aimed to evaluate body compositions of a group of HD and PD patients. Also, we investigated the possible effects of PD solution choices (bicarbonate/lactateebuffered vs lactate-buffered) on body compositions of PD patients. METHODS In this retrospective cross-sectional observational study we examined a total of 152 patients who were selected from a group of 270 HD and 90 PD patients according to inclusion criterias. One hundred ten patients were administered HD treatment whereas 42 were receiving continuous ambulatory PD (CAPD). All HD patients were receiving bicarbonated dialysis using a low flux synthetic dialyzer with an average blood flow of 300 to 350 mL/min with a Kt/V value during each treatment maintained at >1.2. Kt/V. Kt/V values were calculated monthly through predialysis and immediate post-dialysis blood urea nitrogen levels by means of a single-compartment model of HD urea kinetics. All PD patients were under CAPD and were receiving low calcium PD solutions (2000e2500 mL, glucose 1.36%, 2.27%, or 3.86%, lactate buffered Baxter-Dianeal 137 (Istanbul, Turkey) or bicarbonate buffered Physioneal (Castlebar, Ireland). The weekly calculated Kt/V value was 2.0 0.3 during the follow-up period. Patients who had diabetes mellitus, acute infection, recent surgery and hospitalization in last 12 months, chronic inflammatory condition (infectious or rheumatologic origin), nephrotic syndrome, malignancy, or clinically severe malnutrition were excluded. PD patients who were receiving automated PD treatment, receiving icodextrin or amino acid containing solutions, or using a combination of lactate- and bicarbonate/lactateebuffered solutions in the last 12 months were also excluded. Demographic data (age, gender, duration of dialysis, and etiology of the renal failure) were collected from patient charts. The last 6 months routine laboratory evaluations including hemoglobin, serum creatinine, intact parathyroid hormone,
BAL, UYAR, TUTAL ET AL albumin, C reactive protein, calcium, and phosphorus were retrospectively collected and a mean value of each were recorded as final data. Body composition analyses were performed within 30 minutes after a clinically stable and euvolemic dialysis session in HD patients and with empty peritoneal cavity in clinically euvolemic CAPD patients. Body compositions were measured using the Tanita BC-420MA Body Composition Analyzer (Tanita, Tokyo, Japan). For the BIA measurements, the subject stood in an upright position with the bare feet on the analyzer footpads. The impedance between the two feet was measured while an alternating current (50 kHz and w200 mA) passed through the lower body. Fat mass, fat ratio, muscle mass, muscle ratio, total body water, fat-free mass, and visceral fat ratios of each subject were calculated and recorded. As a reminder to readers who are unfamiliar with BIA, because of a measurement technique that accepts body water dissolved in fat or muscle tissue as a part of this tissue, the sum of fat, muscle, and body water masses usually exceeds body weight or sum of ratios reaches greater than 100%. After comparing HD and CAPD patients, we also made a subanalysis of the CAPD group according to buffer choice. CAPD subgroups were as follows: lactate-buffered (n ¼ 16) and bicarbonate/lactateebuffered (n ¼ 26) solution using patient groups. Statistical analyses were performed using SPSS software (Statistical Package for the Social Sciences, version 11.0, SSPS Inc, Chicago, Ill, United States). Normality of data was analyzed using a Kolmogorov-Smirnov test. All numerical variables with normal distribution were expressed as the means standard deviations (SD), whereas variables with skew distribution were expressed as medians and interquartile range. Categorical variables were expressed as percentages and compared using the chi-square test. Normally distributed numeric variables were analyzed by independent samples t or one-way analysis of variance (Post-Hoc Tukey) tests. Skew distributed numeric variables were compared by using the Mann-Whitney U and Kruskal Wallis tests. A P value < .05 was considered to be statistically significant.
RESULTS
HD and CAPD groups were similar in means of demographic characteristics. There was no significant difference between groups in means of biochemical markers except creatinine, hemoglobin (higher in PD group, P ¼ .02, .022, respectively) and calcium levels (lower in PD group, P ¼ .001, Table 1). The body weight (P ¼ .022), BMI (25.8 4.7 vs 23.4 4.9 kg/m2, P ¼ .009), muscle mass (P ¼ .01), fat-free mass (P ¼ .013), and visceral fat ratio (9.5 5.4 vs 7.3 4.1%, P ¼ .022, Table 1) were significantly higher in the CAPD group. The total body water ratios of CAPD patients were also higher (P ¼ .003), but the total body water ratios of HD and CAPD groups were similar (Table 1). Muscle, fat, and fat-free mass ratios of patient groups were also similar. Comparing CAPD subgroups we observed that patients using bicarbonate/lactateebuffered solutions had higher body weights (P ¼ .038), BMI (27.1 5 vs 23.7 3.5 kg/m2, P ¼ .018) values and visceral fat ratios (8.0 5.2 vs 4.6 2.5%, P ¼ .023, Table 2).These patients also tend to have higher fat mass without statistical significance (P ¼ .074). Fat, muscle, and fat-free masses and total body water ratios of PD subgroups were similar.
BODY COMPOSITION ANALYSIS
3491
Table 1. Demographic, Laboratory, and BIA Data for HD and PD Groups Mean SD Median (IR)
Gender (F/M) Age (y) Etiology (n) Diabetes mellitus Hypertension Glomerulonephritis Other Unknown Duration of dialysis (y) Hemoglobin (g/dL) Creatinine (mg/dL) PTH (pg/mL) Calcium (mg/dL) Phosphorus (mg/dL) CRP (mg/L) Albumin (g/dL) Body mass index (kg/m2) Body weight (kg) Muscle mass (kg) Fat-free mass (kg) Fat mass (kg) Total body water (kg) Muscle mass ratio (%) Fat-free mass ratio (%) Visceral fat ratio (%) Fat ratio (%) Total body water ratio (%)
CAPD Patients (n ¼ 42)
HD Patients (n ¼ 110)
21/21 47.9 10.9
50/60 53.8 13.5
15 12 3 6 6 9.0 4.9 11.0 1.2 10.0 2.1 397 (766) 8.7 0.9 4.8 0.9 6.1 (13.7) 3.8 .4 25.8 4.7 67.5 14.0 48.2 8.4 48.9 (13.2) 16.6 9.1 36.3 7.3 72.4 9.1 76.1 (14.8) 9.5 5.4 23.7 9.6 54.6 9.4
48 31 6 15 10 9.5 5.6 10.7 1.2 8.66 1.8 428 (674) 9.2 0.7 5.1 1.1 8.7 (13.1) 3.7 .8 23.4 4.9 61.4 14.6 44.1 8.3 46.6 (13.3) 14.8 9.9 32.4 6.5 73.5 10.4 78.5 (16.7) 7.3 4.1 22.5 11.1 54.2 8.7
Table 2. Demographic, Laboratory and BIA Data for CAPD Patients Using Bicarbonate/lactate and Pure Lactate PD Solutions
P Value
.901 .51 .845
.606 .022 .02 .811 .001 .087 .300 .785 .009 .022 .01 0.013 .285 .003 .525 .307 .022 .517 .818
Abbreviations: BIA, bioelectrical impedance assessment; HD, hemodialysis; PD, peritoneal dialysis; IR, interquartile ratio; CAPD, continuous ambulatory peritoneal dialysis; PTH, parathyroid hormone; CRP, C reactive protein.
Mean SD Median (IR)
Gender (F/M) Age (y) Etiology (n) Diabetes mellitus Hypertension Glomerulonephritis Other Unknown Duration of dialysis (y) Hemoglobin (g/dL) Creatinine (mg/dL) PTH (pg/mL) Calcium (mg/dL) Phosphorus (mg/dL) CRP (mg/L) Albumin (g/dL) Body mass index (kg/m2) Body weight (kg) Muscle mass (kg) Fat-free mass (kg) Fat mass (kg) Total body water (kg) Muscle mass ratio (%) Fat-free mass ratio (%) Visceral fat ratio (%) Fat ratio (%) Total body water ratio (%)
Bicarbonate/lactate Lactate Buffered PD Solution Buffered PD Solution (Physioneal; (n ¼ 26) (Dianeal; (n ¼ 16) P Value
12/14 21.7 8.3
9/7 24.9 10.3
.823 .271 .965
9 8 2 4 3 9.5 5.1 11.1 1.1 9.8 2.8 477 (758) 8.7 .9 5.04 .9 6.8 (13.4) 3.8 0.7 27.1 5
6 4 1 2 3 8.3 4.5 11.3 1.4 10.3 2.2 279 (503) 8.6 .9 4.5 .9 3.8 (14.8) 3.7 0.9 23.7 3.5
.434 .654 .872 .170 .912 .119 .108 .756 .018
70.7 15.3 49.6 8.8 50.5 (13.2) 18.4 10.1 37.5 7.4 71.2 9.7 76.1 (17) 8.0 5.2 24.9 10.3 54.0 10.1
62.2 10.1 46.1 7.6 48.5 (16.4) 13.7 6.5 34.4 6.8 74.3 7.8 75.7 (11.5) 4.6 2.5 21.7 8.3 55.5 8.4
.038 .191 .228 .074 .178 .271 .312 .023 .297 .607
DISCUSSION
Abbreviations: BIA, bioelectrical impedance assessment; CAPD, continuous ambulatory peritoneal dialysis; PD, peritoneal dialysis; PTH, parathyroid hormone.
In this retrospective analysis of 110 HD and 42 CAPD patients, considering biochemical findings, we observed that CAPD patients had higher creatinine values due to lower middle molecule clearance in PD, a very well known phenomenon. Hemoglobin values were also higher in the CAPD group, possibly due to less blood loss compared to the HD procedure. This condition is also a very well known advantage of PD. Also, CAPD patients had lower calcium levels possibly resulting from lower calcium gain caused by using lower calcium PD solutions. We did not include any PD patients using high calcium dialysate and did not standardize this for HD group. Regarding means of nutritional and inflammatory markers, HD and CAPD groups had similar albumin and CRP values and clinical characteristics with no sign of malnutrition. However, despite this similarity, we observed that CAPD patients tend to have higher body weight, BMI, muscle mass, fat-free mass, and visceral fat ratios. Addressing whether higher muscle mass, body fat, or both are associated with longer survival among patients who are on dialysis is a still contraversial issue. Recently, two important studies suggested that having both low fat and/or
muscle mass is an important risk factor for increased mortality.9,10 In the first of these studies, Noori et al analyzed mid-arm muscle circumflex (as an indicator of lean body mass) in 792 HD patients and reported that it is an independent predictor of better mental health and greater survival in HD patients.9 According to Huang et al who analyzed data from 1709 HD patients, having higher fat mass or higher muscle mass seems to be equally protective against mortality.10 BMI is the most commonly applied measure representing the weight-for-height relationship, and a BMI level 30 kg/m2) is associated with a survival advantage whereas, in contrast, a BMI
B
ODY MASS consists of fat mass and fat-free mass (lean mass). Lean mass can serve as an index of muscle mass and somatic protein storage, whereas fat mass more directly reflects energy storage. Notably, there is a progressive decline of lean body mass in chronic kidney disease (CKD) patients indicating ongoing catabolism.1e3 Interestingly, fat mass (or a better body fat distribution) may be
From the Departments of Nephrology (Z.B., M.E.U., E.T., O.G., S.S.) and General Surgery (M.H.), Baskent University Faculty of Medicine, Ankara, Turkey. Address reprint requests to Emre Tutal, Associate Professor, Department of Nephrology, Baskent University Faculty of Medicine, Besevler, Ankara, 06490, Turkey. E-mail: emretutal@gmail. com
ª 2013 Published by Elsevier Inc. 360 Park Avenue South, New York, NY 10010-1710
0041-1345/13/$esee front matter http://dx.doi.org/10.1016/j.transproceed.2013.08.097
Transplantation Proceedings, 45, 3489e3493 (2013)
3489
3490
protective rather than deleterious in maintenance dialysis, and a reduction in fat mass over time seems to be associated with poor survival.4,5 Bioelectrical impedance analysis (BIA) has significant potential as a complementary method to standard anthropometric techniques in the nutritional monitoring of CKD patients. BIA is a practical bedside tool for assessment of body composition that provides more consistent and reproducible results than standard anthropometry alone.6 Recent studies have reported better survival rates in overweight and obese hemodialysis (HD) patients. This is known as paradoxical obesity or reverse epidemiology.4 Additionally, atherosclerosis often coexists with a low body mass index (BMI) and a low serum albumin level, two factors that are well known predictors of poor survival in HD patients.2 Peritoneal dialysis (PD) offers potential advantages compared with HD including continuous calorie supply by glucose containing dialysate usage, avoiding the catabolic stimuli of foreign material, and having less restrictions for dietary and fluid intake. In this sense, it has already been proven that pure bicarbonate-buffered PD solutions have better success in correcting metabolic acidosis.7,8 However, PD patients have their own risk of protein malnutrition because high calorie intake and abdominal discomfort might cause decreased oral intake. In the present study, we aimed to evaluate body compositions of a group of HD and PD patients. Also, we investigated the possible effects of PD solution choices (bicarbonate/lactateebuffered vs lactate-buffered) on body compositions of PD patients. METHODS In this retrospective cross-sectional observational study we examined a total of 152 patients who were selected from a group of 270 HD and 90 PD patients according to inclusion criterias. One hundred ten patients were administered HD treatment whereas 42 were receiving continuous ambulatory PD (CAPD). All HD patients were receiving bicarbonated dialysis using a low flux synthetic dialyzer with an average blood flow of 300 to 350 mL/min with a Kt/V value during each treatment maintained at >1.2. Kt/V. Kt/V values were calculated monthly through predialysis and immediate post-dialysis blood urea nitrogen levels by means of a single-compartment model of HD urea kinetics. All PD patients were under CAPD and were receiving low calcium PD solutions (2000e2500 mL, glucose 1.36%, 2.27%, or 3.86%, lactate buffered Baxter-Dianeal 137 (Istanbul, Turkey) or bicarbonate buffered Physioneal (Castlebar, Ireland). The weekly calculated Kt/V value was 2.0 0.3 during the follow-up period. Patients who had diabetes mellitus, acute infection, recent surgery and hospitalization in last 12 months, chronic inflammatory condition (infectious or rheumatologic origin), nephrotic syndrome, malignancy, or clinically severe malnutrition were excluded. PD patients who were receiving automated PD treatment, receiving icodextrin or amino acid containing solutions, or using a combination of lactate- and bicarbonate/lactateebuffered solutions in the last 12 months were also excluded. Demographic data (age, gender, duration of dialysis, and etiology of the renal failure) were collected from patient charts. The last 6 months routine laboratory evaluations including hemoglobin, serum creatinine, intact parathyroid hormone,
BAL, UYAR, TUTAL ET AL albumin, C reactive protein, calcium, and phosphorus were retrospectively collected and a mean value of each were recorded as final data. Body composition analyses were performed within 30 minutes after a clinically stable and euvolemic dialysis session in HD patients and with empty peritoneal cavity in clinically euvolemic CAPD patients. Body compositions were measured using the Tanita BC-420MA Body Composition Analyzer (Tanita, Tokyo, Japan). For the BIA measurements, the subject stood in an upright position with the bare feet on the analyzer footpads. The impedance between the two feet was measured while an alternating current (50 kHz and w200 mA) passed through the lower body. Fat mass, fat ratio, muscle mass, muscle ratio, total body water, fat-free mass, and visceral fat ratios of each subject were calculated and recorded. As a reminder to readers who are unfamiliar with BIA, because of a measurement technique that accepts body water dissolved in fat or muscle tissue as a part of this tissue, the sum of fat, muscle, and body water masses usually exceeds body weight or sum of ratios reaches greater than 100%. After comparing HD and CAPD patients, we also made a subanalysis of the CAPD group according to buffer choice. CAPD subgroups were as follows: lactate-buffered (n ¼ 16) and bicarbonate/lactateebuffered (n ¼ 26) solution using patient groups. Statistical analyses were performed using SPSS software (Statistical Package for the Social Sciences, version 11.0, SSPS Inc, Chicago, Ill, United States). Normality of data was analyzed using a Kolmogorov-Smirnov test. All numerical variables with normal distribution were expressed as the means standard deviations (SD), whereas variables with skew distribution were expressed as medians and interquartile range. Categorical variables were expressed as percentages and compared using the chi-square test. Normally distributed numeric variables were analyzed by independent samples t or one-way analysis of variance (Post-Hoc Tukey) tests. Skew distributed numeric variables were compared by using the Mann-Whitney U and Kruskal Wallis tests. A P value < .05 was considered to be statistically significant.
RESULTS
HD and CAPD groups were similar in means of demographic characteristics. There was no significant difference between groups in means of biochemical markers except creatinine, hemoglobin (higher in PD group, P ¼ .02, .022, respectively) and calcium levels (lower in PD group, P ¼ .001, Table 1). The body weight (P ¼ .022), BMI (25.8 4.7 vs 23.4 4.9 kg/m2, P ¼ .009), muscle mass (P ¼ .01), fat-free mass (P ¼ .013), and visceral fat ratio (9.5 5.4 vs 7.3 4.1%, P ¼ .022, Table 1) were significantly higher in the CAPD group. The total body water ratios of CAPD patients were also higher (P ¼ .003), but the total body water ratios of HD and CAPD groups were similar (Table 1). Muscle, fat, and fat-free mass ratios of patient groups were also similar. Comparing CAPD subgroups we observed that patients using bicarbonate/lactateebuffered solutions had higher body weights (P ¼ .038), BMI (27.1 5 vs 23.7 3.5 kg/m2, P ¼ .018) values and visceral fat ratios (8.0 5.2 vs 4.6 2.5%, P ¼ .023, Table 2).These patients also tend to have higher fat mass without statistical significance (P ¼ .074). Fat, muscle, and fat-free masses and total body water ratios of PD subgroups were similar.
BODY COMPOSITION ANALYSIS
3491
Table 1. Demographic, Laboratory, and BIA Data for HD and PD Groups Mean SD Median (IR)
Gender (F/M) Age (y) Etiology (n) Diabetes mellitus Hypertension Glomerulonephritis Other Unknown Duration of dialysis (y) Hemoglobin (g/dL) Creatinine (mg/dL) PTH (pg/mL) Calcium (mg/dL) Phosphorus (mg/dL) CRP (mg/L) Albumin (g/dL) Body mass index (kg/m2) Body weight (kg) Muscle mass (kg) Fat-free mass (kg) Fat mass (kg) Total body water (kg) Muscle mass ratio (%) Fat-free mass ratio (%) Visceral fat ratio (%) Fat ratio (%) Total body water ratio (%)
CAPD Patients (n ¼ 42)
HD Patients (n ¼ 110)
21/21 47.9 10.9
50/60 53.8 13.5
15 12 3 6 6 9.0 4.9 11.0 1.2 10.0 2.1 397 (766) 8.7 0.9 4.8 0.9 6.1 (13.7) 3.8 .4 25.8 4.7 67.5 14.0 48.2 8.4 48.9 (13.2) 16.6 9.1 36.3 7.3 72.4 9.1 76.1 (14.8) 9.5 5.4 23.7 9.6 54.6 9.4
48 31 6 15 10 9.5 5.6 10.7 1.2 8.66 1.8 428 (674) 9.2 0.7 5.1 1.1 8.7 (13.1) 3.7 .8 23.4 4.9 61.4 14.6 44.1 8.3 46.6 (13.3) 14.8 9.9 32.4 6.5 73.5 10.4 78.5 (16.7) 7.3 4.1 22.5 11.1 54.2 8.7
Table 2. Demographic, Laboratory and BIA Data for CAPD Patients Using Bicarbonate/lactate and Pure Lactate PD Solutions
P Value
.901 .51 .845
.606 .022 .02 .811 .001 .087 .300 .785 .009 .022 .01 0.013 .285 .003 .525 .307 .022 .517 .818
Abbreviations: BIA, bioelectrical impedance assessment; HD, hemodialysis; PD, peritoneal dialysis; IR, interquartile ratio; CAPD, continuous ambulatory peritoneal dialysis; PTH, parathyroid hormone; CRP, C reactive protein.
Mean SD Median (IR)
Gender (F/M) Age (y) Etiology (n) Diabetes mellitus Hypertension Glomerulonephritis Other Unknown Duration of dialysis (y) Hemoglobin (g/dL) Creatinine (mg/dL) PTH (pg/mL) Calcium (mg/dL) Phosphorus (mg/dL) CRP (mg/L) Albumin (g/dL) Body mass index (kg/m2) Body weight (kg) Muscle mass (kg) Fat-free mass (kg) Fat mass (kg) Total body water (kg) Muscle mass ratio (%) Fat-free mass ratio (%) Visceral fat ratio (%) Fat ratio (%) Total body water ratio (%)
Bicarbonate/lactate Lactate Buffered PD Solution Buffered PD Solution (Physioneal; (n ¼ 26) (Dianeal; (n ¼ 16) P Value
12/14 21.7 8.3
9/7 24.9 10.3
.823 .271 .965
9 8 2 4 3 9.5 5.1 11.1 1.1 9.8 2.8 477 (758) 8.7 .9 5.04 .9 6.8 (13.4) 3.8 0.7 27.1 5
6 4 1 2 3 8.3 4.5 11.3 1.4 10.3 2.2 279 (503) 8.6 .9 4.5 .9 3.8 (14.8) 3.7 0.9 23.7 3.5
.434 .654 .872 .170 .912 .119 .108 .756 .018
70.7 15.3 49.6 8.8 50.5 (13.2) 18.4 10.1 37.5 7.4 71.2 9.7 76.1 (17) 8.0 5.2 24.9 10.3 54.0 10.1
62.2 10.1 46.1 7.6 48.5 (16.4) 13.7 6.5 34.4 6.8 74.3 7.8 75.7 (11.5) 4.6 2.5 21.7 8.3 55.5 8.4
.038 .191 .228 .074 .178 .271 .312 .023 .297 .607
DISCUSSION
Abbreviations: BIA, bioelectrical impedance assessment; CAPD, continuous ambulatory peritoneal dialysis; PD, peritoneal dialysis; PTH, parathyroid hormone.
In this retrospective analysis of 110 HD and 42 CAPD patients, considering biochemical findings, we observed that CAPD patients had higher creatinine values due to lower middle molecule clearance in PD, a very well known phenomenon. Hemoglobin values were also higher in the CAPD group, possibly due to less blood loss compared to the HD procedure. This condition is also a very well known advantage of PD. Also, CAPD patients had lower calcium levels possibly resulting from lower calcium gain caused by using lower calcium PD solutions. We did not include any PD patients using high calcium dialysate and did not standardize this for HD group. Regarding means of nutritional and inflammatory markers, HD and CAPD groups had similar albumin and CRP values and clinical characteristics with no sign of malnutrition. However, despite this similarity, we observed that CAPD patients tend to have higher body weight, BMI, muscle mass, fat-free mass, and visceral fat ratios. Addressing whether higher muscle mass, body fat, or both are associated with longer survival among patients who are on dialysis is a still contraversial issue. Recently, two important studies suggested that having both low fat and/or
muscle mass is an important risk factor for increased mortality.9,10 In the first of these studies, Noori et al analyzed mid-arm muscle circumflex (as an indicator of lean body mass) in 792 HD patients and reported that it is an independent predictor of better mental health and greater survival in HD patients.9 According to Huang et al who analyzed data from 1709 HD patients, having higher fat mass or higher muscle mass seems to be equally protective against mortality.10 BMI is the most commonly applied measure representing the weight-for-height relationship, and a BMI level 30 kg/m2) is associated with a survival advantage whereas, in contrast, a BMI
