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Assessment of Malnutrition of Dialysis Patients and Comparison of Nutritional Parameters of CAPD and Hemodialysis Patients

Malnutrition is common and the major risk factor of mortality of end stage renal disease (ESRD) patients. The aim of this study is to assess nutritional status of malnutrition patients on dialysis by various methods and compare nutritional parameters of continuous ambulatory peritoneal dialysis (CAPD) patients with hemodialysis patients. 137 patients on dialysis from April 2009 to July 2013 were enrolled. Nutritional parameters of 66 CAPD and 71 hemodialysis patients were investigated by anthropometry, biochemical study, diet analysis and questionnaires. Malnutrition patients were selected by body mass index (BMI), serum albumin and pre-albumin based on International Society of Renal Nutrition and Metabolism (ISRNM) diagnostic criteria for protein-energy wasting and compared with non-malnutrition patients. In comparison of CAPD and hemodialysis patients, most anthropometric values showed no significant difference except total body water (TBW). TBW was lower in CAPD patients (P=0.024). Although serum albumin was slightly higher in hemodialysis patients (P=0.047), pre-albumin were significantly higher in CAPD patients (P=0.000). Serum blood urea nitrogen (BUN) was higher in hemodialysis patients (P=0.000). In diet analysis, Total calorie (P=0.000) and total cholesterol (P=0.012) intakes were higher in CAPD patients. Mean subjective global assessment (SGA) grade was higher in CAPD patients (P=0.003). Several nutritional parameters of CAPD patients were better than hemodialysis patients implying more intensive therapeutic approach may be needed for hemodialysis patients. We have to understand multiple factors contributing malnutrition of ESRD patients and individualized therapeutic approach is needed.


INTRODUCTION
Malnutrition is common in dialysis patients with a prevalence ranging from 18% to 56% (Fouque et al., 2008;Dukkipati and Kopple, 2009). It is a major risk factor of mortality in patients on dialysis and impairs quality of life Dong et al., 2011). Malnutrition of dialysis patients is caused by multiple factors such as inadequate protein and calorie intake, loss of appetite, inflammation, loss of residual renal function, inadequate dialysis, insulin resistance and superimposed co-morbid conditions Bossola et al., 2005;Chung, 2007). Because malnutrition is the major co-morbid condition of patients on dialysis, regular monitoring of nutritional status, delivering adequate food intake, maintenance of adequate dialysis dose and therapeutic intervention are necessary. Dietary counseling should be a part of treatment to provide adequate calorie and protein intake (Prasad et al., 2008;Martin-Del-Campo et al., 2009) Modality of dialysis also has effect on patient's nutritional status. It could cause loss of protein and soluble vitamins and suppress appetite (Chung, 2007). But which modality is superior in nutritional aspects is not yet clear . In this study, nutritional parameters of dialysis patients were investigated by diet analysis, anthropometry, laboratory study and questionnaires and we compared nutritional parameters of hemodialysis patients and CAPD patients. Furthermore, malnutrition patients were selected based on ISRNM diagnostic criteria for PEW and compared with non-malnutrition patients. Between April 2009 and July 2013, total two or three times of diet analysis, anthropometry and serum nutritional prognostic marker are investigated. Blood sampling was performed shortly before starting dialysis. We used mean value of investigations.

Diet and nutrient analysis
We estimated diet uptake by consecutive three days quantitative diet record method. We used real food sized food model for accurate quantification. Nutritional experts back up this diet record by one-to-one interview with patients. Diet record is analyzed by Nutrient analyzing program CAN Pro (programmed by Korean Nutrition Information Center, ver 3.0) for each nutrient quantification. We used mean value for three days nutrient uptake. For peritoneal dialysis patients, 70% of dialysate calorie added to total calorie intake considering dextrose concentration of dialysate, dialysate volume, and dialysis frequency.

Subjective Global Assessment (SGA) score
SGA score is a clinical technique which assesses nutritional status based on features of the history and physical examination (Sum et al., 2017). SGA grade consists of 7 assessment items (weight change, intake, gastrointestinal symptom, functional status, metabolic demands, fat store, muscle store and edema). Each item is scored 1 to 7. Considering these scores, total SGA score is rated subjectively not by sum or mean of the scores (Detsky et al., 1987).

Selection of malnutrition patients
The ISRNM (International Society of Renal Nutrition and Metabolism) proposed comprehensive diagnostic criteria for PEW (protein energy wasting) in patients with ESRD (Fouque et al., 2008). A clinical diagnosis of PEW according to the ISRNM guidelines requires at least three out of the four main categories (serum chemistry, body mass, muscle mass, and dietary intake). Based on the criteria, patients satisfying BMI < 23 kg/m 2 and serum albumin < 3.8 g/dl (or serum prealbumin < 30 mg/dl) were selected as malnutrition patients and they were compared with non-malnutrition patients.

Statistical analysis
The patients were divided into CAPD and hemodialysis groups and variables were compared between these groups.
Continuous variables were expressed as the mean ± standard deviation. The Student t-test and Pearson's chi-squared test or Mann-Whitney test were used to compare baseline characteristics, anthropometric values, diet and laboratory study between two groups. Binary logistic regression was used to analyze risk factors of malnutrition. Null hypotheses of no differences were rejected if the P values were less than 0.05.

Comparison of hemodialysis and CAPD patients
Mean age of hemodialysis patients was higher than  Table 1 shows anthropometric values of two groups. Total body water (TBW) (P=0.026) and Triceps skin fold thickness (P=0.049) were higher in hemodialysis group. BMI and other anthropometric values showed no significant difference between two groups. Table 2 shows nutrient intakes of patients on dialysis. Total calorie (P<0.001) and Total cholesterol intakes (P=0.012) were higher in CAPD patients.
Other nutrient intake including protein, lipid, microelements, and vitamins showed no significant difference between two groups.
The possible serum biomarkers are useful nutritional parameter of dialysis patients. As shown in Fig. 1, prealbumin were significantly higher in CAPD group (P<0.05).
However, the BUN was higher in hemodialysis group (P<0.001). The other biochemical paramerters in serum including albumin were not differed significantly among the two groups ( Fig. 1 and Table 3).
SGA grade is well known method for assessing nutritional status of patients. Table 4 shows numbers of patients belong to each SGA grade. No one was under SGA score 5. Mean SGA score was higher in CAPD patients (P=0.003). Also, percent of highest SGA score was higher in CAPD patients (72.7% versus 40.8%). Lipid profile of CAPD and hemo- higher in CAPD patients ( Table 5).

Comparison of malnutrition and non-malnutrition patients
Total 33 (24%) of 137 patients were malnutrition patients.
Prevalence of malnutrition of CAPD and hemodialysis patients had no significant differences (P=0.842). Table 6 shows comparison of serum biochemistries, lipid profiles, anthropometric values and dietary intake which had significant differences between malnutrition and non-malnutrition patients. Triglyceride level was higher in non-malnutrition patients but HDL was higher in malnutrition patients. Several anthropometric values were significantly higher in nonmalnutrition patients. Interestingly, malnutrition patient intake more total calorie and nutrients including protein, vegetable lipid, animal lipid and carbohydrate. Comparison of malnu-

DISCUSSION
High BMI is associated with increased survival in patients on dialysis and low BMI is associated with an increased risk of mortality (Stack et al., 2004). But BMI can be affected by fat mass or hydration status. Especially CAPD patient leads to greater volume expansion than hemodialysis patients and survival advantage associated with a higher BMI is less apparent in CAPD patients (Snyder et al., 2003). In this study BMI of CAPD and hemodialysis groups were 22.83 and 22.43, showing no significant differences between the two groups.
Reduced muscle mass is associated with inflammation, which plays central role in malnutrition, and increased mortality in patients on dialysis (Ramkumar et al., 2005;Honda et al., 2007). Measurement of mid-arm muscle circumference is commonly used for anthropometric assessment.
But it is not accurate because there is substantial error which depends on observers and could be affected by hydration status (Chung et al., 2007). But in our results, there are no significant differences between the two groups.
The accuracy of dietary intake assessment by quantitative diet record method depends on the patients' ability to quantify the amount of food eaten (Bargman, 1996). In this study, real food sized food model were used for accurate quantification and Nutritional experts backed up the diet record by one-to-one interview with patients.
Protein intake of 1.2 g/kg per day was recommend by KDOQI guidelines. The European guidelines warned against  recommends protein intake >1.0 g/kg per day (Dombros, 2005). In this study, Dietary protein uptake of Both CAPD and hemodialysis patients were below 1.0 g/kg and showed  (Fouque et al., 2008).
Current studies in chronic kidney disease (CKD) including dialysis populations consistently have shown the strong mortality-predictability of several markers such as hypoalbuminemia, low serum cholesterol levels, low body mass index, and reduced dietary protein intake ). Among various nutritional parameters low serum albumin is a strong predictor of mortality in patients on dialysis (Han et al., 2007;Spiegel and Breyer, 1994). However, serum albumin has 20 days of long half-life and can be affected by multiple factors such as inflammation, fluid status of patients, losses into dialysate (Han et al., 1996;Cheng et al., 2005 inflammation-associated wasting process, so called proteinenergy wasting, is well known to be an important pathogenesis of malnutrition of ESRD patients (Stenvinkel et al., 2000;de Mutsert et al., 2008). Inflammation, hypercatabolic illness, IGF-1, growth hormone, chronic acidosis, resistance to insulin and Nutrient loss during dialysis can cause loss of muscle mass despite adequate nutrient intake (Dukkipati and Kopple, 2009;Chung et al., 2007). In this study, despite higher dietary energy and nutrient intake, malnutrition patients consistently had worse anthropometric values. Except insufficient dietary intake, multiple factors including inflammation, loss of residual renal function, inadequate dialysis, insulin resistance and superimposed co-morbid conditions are associated with malnutrition of ESRD patients . We have to understand these factors and individualized therapeutic approach is needed.

CONFLICT OF INTEREST
The authors have no conflict of interest to declare.