Cardiovascular disease is the main factor in all-cause death in hemodialysis patients .This is probably due to the unique risk factors in hemodialysis patients, including rapid electrolyte change, prolonged QT interval, calcium and phosphorus metabolism disorder, sympathetic excitation, uremic toxin invasion, and hemodialysis related hemodynamic changes. In this study, the most common cause of death (29 cases) in MHD patients was cardiovascular diseases, including heart failure, arrhythmia, ischemic heart disease, and sudden cardiac death. Kaplan-Meier univariate analysis showed that old age was an independent risk factor for death in MHD patients, that serum albumin level could directly reflect the nutritional status of patients, and that protein-energy malnutrition is common in MHD patients (up to 23–73%). Univariate survival analysis suggested that an albumin level of < 35g/L was an independent risk factor for death in hemodialysis patients. Reduced albumin is mainly related to insufficient intake, uremic toxin invasion, delayed gastric emptying, loss of nutrients in dialysis, endocrine disorders, metabolic acidosis, and increased energy consumption due to complications, which aggravate malnutrition in MHD patients and increase their mortality. Hypoproteinemia increases the mortality rate in MHD patients.
Phase angle is reported to be an independent risk factor associated with malnutrition in CKD patients. Currently, phase angle is used in the study of cancer, liver cirrhosis, hemodialysis, and surgical outcomes, and found that phase angle with poor. Phase angle is an affordable, objective, quantifiable, and convenient measurement without exposure to radiation. Phase angle, measure of cell resistivity, reflects cell membrane integrity and overall cellular health. As a sensitive indicator of malnutrition, phase angle can be used to detect clinical nutritional status changes that are related to changes in body composition due to muscle loss or fluid overload. A strong positive correlation between phase angle and traditional nutritional screening tools (e.g., MUST, SGN), as well as various nutritional risk markers has been demonstrated. Additionally, the European Society for Parenteral and Enteral Nutrition recognizes the prognostic value of phase angle in patients requiring nutritional therapy, whereby lower phase angles are associated with worse outcomes in ICU patients and higher phase angles are associated with improved survival. By monitoring the patient’s phase angle, intensive care specialists can noninvasively assess the patient’s nutritional status[13, 14]. Phase angle can reflect early cellular dysfunction, which can indicate the occurrence, development and prognosis of a disease, such as inflammation or cancer. Phase angle is calculated using the formula: arctangent (capacitive reactance/impedance×180°/π). The theoretical basis for phase angle representation of somatic health level is as follows[15, 16]: the “conductive part” of the human body includes ICW, ECW and other conductive components at the cellular level, which produce resistance to current. The voltage difference across the cell membrane is considered the capacitance, which produces capacitive reactance to the current. Due to the presence of capacitive reactance current passing through the body produces phase shifts in the cell membrane that are out of step with the voltage. Therefore, phase angle is closely associated with the number, integrity and continuity of cell membranes, as well as with the distribution of ECW and ICW. Hence, phase angle is a comprehensive reflection of the influence of inflammation, immunity, nutrition, and other factors on cell health and function. Gonzalez et al. analyzed the phase angle of 1442 healthy subjects, and found that reduction in phase angle due to changes in ECW could be measured when sarcopenia had not occurred in the consumption state, such as inflammation. Here, phase angle was low, which may be associated with malnutrition and chronic inflammation in dialysis patients. Bioelectrical impedance analysis is a simple, noninvasive, and reliable technique for estimating body composition and has various applications, including in the prediction of Type 2 diabetes, muscle dysfunction, hydration, and nutritional status. Phase angle is an indicator of bioelectrical impedance and significantly correlates with cancer prognosis. This study shows that MHD patients with low phase angles (< 4.5°) had 3.6 times higher the risk of death when compared with those with high phase angles (≥ 4.5°). The underlying mechanism by which low phase angle can predict prognosis in MHD patients. In addition to the amount of water in a patient’s body, phase angle also reflects the state of cell function and cell membrane integrity. Reduced phase angle often indicates reduced extracellular matrix and increased apoptosis.