Ethics
This study was approved by the Ethics Committee of Tianjin Third Central Hospital. All research subjects have signed the informed consent.
Patient selection
There were 166 MHD patients in our hospital from September to December 2019. A total of 200 patients were screened, and 34 patients were excluded based on the inclusion criteria: age ≥18 years old and dialysis age ≥3 months as well as the exclusion criteria: patients with known malignant tumors, patients hospitalized for severe infection in the past month and patients with new cerebral infarction or cerebral hemorrhage in the past three months.
Research methods
Questionnaire survey
The researchers used a unified questionnaire to conduct on-site surveys of the research objects. The contents of the questionnaire include 1) general information such as gender, age, dialysis age, marital status, and education level; 2) the original disease status, including whether having diabetes and high blood pressure; 3) living conditions including daily defecation, daily sleep time, daily protein and staple food intake, weekly exercise time, whether there is stomatitis, and whether taking vitamins or amino acids.
Dialysis data collection
The patients’ hemodialysis treatment information was collected, including weight before and after dialysis, blood pressure, ultrafiltration volume, dialysis method, blood flow and dialysis access.
Biochemical indicators collection
The past 3 months’ data of the enrolled patients at the dialysis center were collected, including blood routine, liver and kidney function, electrolytes, parathyroid hormone, blood sugar, blood lipids, ferritin, transfer iron saturation, and other indicators.
Body measurement
All subjects were measured after dialysis, including height, weight, abdominal circumference, calf circumference, upper arm circumference (AC), triceps skinfold thickness (TSF), body mass index (BMI), and main handgrip strength. For measuring the abdominal circumference and calf circumference, let patients take a vertical standing posture and fully relax to distribute the weight evenly. Abdominal circumference is the length of the circle around the abdomen through the navel, and calf circumference is the length of the circle at the calf’s thickest part. A standing posture with feet shoulder-width apart, hands drooping, and non-fistula side hands holding grips was for measuring the main handgrip strength. A skinfold thickness meter was used to measure the thickness of the triceps skinfold at the point 2 cm above the midpoint between the acromion and the olecranon of the non-fistula arm. A tape around the arm at the midpoint was used to measure the upper arm circumference.
All the above indicators were measured 3 times. If the measurement values were very close, their average was taken as the final result. If the measurement values were quite different, the average of the closest two was used as the final results.
Scoring scale
NS2002, PG-SGA and MUST scores were calculated for all participants.
PEW diagnostic criteria
Patients were diagnosed as PEW if they met at least one of the following criteria according to the recommendation by ISRNM in 2008. First, their biochemical indicators met serum albumin <3.8g/dL, serum pre-Alb<30mg/dL, and serum cholesterol<259 mmol/L; Second, they had unexpected body mass loss to BMI<23 kg/m2, unintentional weight loss of 5% within 3 months, 10% weight loss within 6 months, or fat content< 10%; Third, their muscle mass loss reached 5% within 3 months or 10% within 6 months, upper arm midsection muscle circumference (AMC) decreased by > 10% or serum creatinine <618 μmol/L, where AMC (cm ) = Upper arm circumference (cm)-3.14 × TSF (cm); Fourth, they had unintentional dietary protein intake <0.8 g·(kg·d)-1 for at least 2 months or unintentional dietary energy intake <25 kcal·(kg·d)-1 for at least 2 months. According to BMI, PEW was divided into 3 different levels: severe level with BMI≤18.5 kg/m2; moderate level with BMI 18.6-20.0kg/m2 and mild level with BMI>20.0 kg/m2[6]. Because of insufficient accuracy in patients’ long-term weight monitoring and the significant effects of water load of the dialysis interval on patients’ BMI, post-dialysis BMI, which is relatively objective and easily accessible, was selected as the indicator for body mass reduction.
Statistical analysis
SPSS 26.0 software was used for statistical analysis. The measurement data conforming to the normal distribution were expressed as`x ± s. T test was used to compare the measurement data of PEW patients and non-PEW patients, and the x2 test was used to compare the count data. ROC curve analysis was used to evaluate the diagnostic efficacy of each scoring scale. A p<0.05 indicates a statistically significant difference.