Association between phase angle and adverse clinical outcomes in hospitalized patients with COVID-19: A systematic review

Association between segmental phase angles and functional independence measure scores in hospitalized adults following stroke: A retrospective cohort study

BACKGROUND

This study investigated the association between segmental phase angles and functional outcomes in patients after stroke, hypothesizing that increased segmental phase angle correlates with improved functional status.

METHODS

A retrospective cohort study of 1012 patients after stroke was conducted. Whole body and segmental phase angles were measured using bioelectrical impedance analysis within 3 days of admission. Our exposure of interest was segmental phase angle measured via a multifrequency bioelectrical impedance analyzer and calculated as phase angle = arctangent (Xc/R) × (180/π), where R is the resistance of the right half of the body and Xc is the reactance measured at 50 kHz. The primary outcomes were the motor subscale of the functional independence measure (FIM) at discharge and FIM change between admission and discharge. Secondary outcomes included FIM scores for specific activities. Multiple linear regression analysis was performed to assess associations.

RESULTS

Phase angles of the healthy upper and lower limbs demonstrated stronger associations with discharge FIM motor scores (β = 0.175 and β = 0.105, respectively) and FIM motor gain (β = 0.242 and β = 0.092, respectively) compared with whole body or paretic limb phase angles. Upper limb phase angles were more closely related to grooming and toileting abilities, whereas lower limb phase angles were associated with both toileting and locomotion at discharge.

CONCLUSION

Segmental phase angles, particularly those of the nonparetic limbs, are promising predictors of functional outcomes in patients after stroke. Assessing segmental phase angles may guide targeted interventions and rehabilitation strategies for improving specific activities of daily living.

Phase angle as a prognostic factor in patients with cancer: a systematic review of the existing evidence via a meta-analysis

BACKGROUND

the phase angle (PA) is expressed via bioelectrical impedance and an indicator of cell membrane health, integrity, hydration, and nutritional status. The associations between PA and cancer survival are inconsistent and unclear. This study aimed to assess PA's role as a prognostic marker of cancer survival.

METHODS

we searched PubMed and EMBASE to identify all relevant studies up to December 2023. A meta-analysis was performed to clarify PA's prognostic role for cancer patients.

RESULTS

a total of 30 studies covering 6587 participants were included in this study. There was a significant prognostic role for PA in the context of cancer patients' survival (HR = 0.73; 95 % CI, 0.66-0.81, p < 0.0001, I2 = 0.0 %). Patients with low PA values were 27 % less likely to survive than patients with high values. Our subgroup analyses showed that geographical population (American: HR = 0.66, 95 % CI: 0.55-0.79, I2 = 0.0 %; European: HR = 0.63, 95 % CI: 0.47-0.84, I2 = 23.2 %; Asian: HR = 0.48, 95 % CI: 0.31-0.74), the type of cancer (head and neck, colorectal, lung, or pancreatic cancer), and type of therapy (palliative vs. non-palliative treatment) did not change the prognostic value.

CONCLUSIONS

the findings highlight the potential of PA to be a non-invasive, cost-effective prognostic tool in oncological care.

Bioimpedance formalism: A new approach for accessing the health status of cell and tissues

This manuscript describes a novel methodology for studying relaxation dynamics in tissues and cells using characteristic frequency of bioimpedance spectroscopy measurements. The Bioimpedance Formalism allows for the simultaneous study of bioelectrical parameters in the frequency and time domains, providing insight into possible relaxation processes occurring in the tissue or cell of interest. Results from the Cole-Cole analysis showed no multiple relaxation processes associated with heterogeneity, with a visible age group separation in males compared with females. The study of the relaxation dynamic in the time domain revealed that the β parameter can be used to analyse the charge carriers in tissues, cells, or cancer cells, potentially leading to new diagnostic and therapeutic approaches for cancer and other diseases. Overall, this approach presents a promising area of research for gaining insights into the electrical properties of tissues and cells using bioimpedance methods.

Phase angle as an indicator of body composition and physical performance in handball players

BACKGROUND

Phase angle (PhA), obtained from the bioimpedance analysis, is widely used in clinical situations and in sports. This study evaluated the association between PhA with body composition and physical performance of handball athletes.

METHODS

43 national-level players (22.19 ± 3.86 years) of both sexes were evaluated regarding anthropometry, body composition, squat (SJ) and countermovement (CMJ) jumps, handgrip strength, and cardiorespiratory fitness.

RESULTS

We verified a correlation between PhA of the whole body and fat-free mass (r = 0.511), body mass index (r = 0.307), and body fat % (r = -0.303). There was a positive correlation between PhA of the whole body and SJ (r = 0.376), CMJ (r = 0.419), and handgrip for the dominant hand (r = 0.448). Moreover, PhA of the upper limbs was more strongly correlated with handgrip for the dominant (r = 0.630) and non-dominant hand (r = 0.575) compared to PhA of the whole body considering both sexes. Similarly, segmental PhA had a stronger significant correlation with SJ (r = 0.402) and handgrip for the dominant hand (r = 0.482) in males, as well as CMJ (r = 0.602) in females, compared to PhA of the whole body.

CONCLUSION

PhA of the whole body was positively related to fat-free mass, body mass index, body fat %, and lower- and upper-limbs strength in handball athletes. Segmental PhA might be used as a tool for estimating lower and upper limbs performance considering the sex, in preference to the PhA of the whole body.

Total and segmental phase angle in a cohort of hospitalised patients with COVID-19: mortality prediction and changes throughout hospitalisation

Body composition and phase angle (PhA) have been used to predict mortality in multiple diseases. However, little has been studied regarding segmental measurements, which could potentially help assess subtle changes in specific tissue segments. This study aimed to identify the total PhA cut-off point associated with mortality risk and changes in body composition within a week of hospitalisation in non-critical hospitalised patients with COVID-19. A cohort study was conducted where patients underwent to a complete nutritional assessment upon admission and after seven days, and followed up until hospital discharge or death. A receiver operating characteristic curve was constructed to determine the PhA cut-off point, and the Kaplan–Meier estimator was used to determine survival analysis. Segmental and complete body compositions on admission and after 7 d were compared. We included 110 patients (60 men) with a mean age of 50·5 ± 15·0 years and a median BMI of 28·5 (IQR, 25·6–33·5) kg/m2. The median length of hospital stay was 6 (IQR, 4–9) d, and the mortality rate was 13·6 %. The PhA cut-off point obtained was 4°, with significant differences in the survival rate (P < 0·001) and mortality (HR = 5·81, 95 % CI: 1·80, 18·67, P = 0·003). Segmental and whole-body compositions were negatively affected within one week of hospitalisation, with changes in the approach by the graphical method in both sexes. Nutritional status deteriorates within a week of hospitalisation. PhA < 4° is strongly associated with increased mortality in non-critical hospitalised patients with COVID-19.

The role of bioelectrical phase angle in patients with heart failure

The most challenging feature of heart failure (HF) still remains the evaluation of congestion. Residual congestion at discharge and the difficulties in perfectly dosing therapies in order to balance the hydration status of the patient are the most worrisome issues when dealing with HF.The use of bioimpedance vector analysis (BIVA) might promote a different approach in the general management of patients with HF. BIVA is a reliable, fast, bedside tool able to assess the congestion status. It proved to be helpful to physicians for diagnosing congestive status, managing therapies, and providing prognostic information in the setting of HF.Bioelectrical Phase Angle (PhA) - as derived from equations related to the parameters of BIVA - recently surged as a possible biomarker for patients with HF. Studies provided data about the application of PhA in the clinical management and in the overall risk stratification of HF patients.Basically, the use of PhA might be considered as a holistic evaluation of patients with HF which includes the need for a multiparametric approach able to effectively depict the clinical status of patients. There is no definite biomarker able to comprehensively describe and identify all the features of HF patient, but scores based on molecules/techniques able to explore the different pathogenetic mechanisms of HF are desirable.The aim of this review was to provide a comprehensive evaluation of literature related to PhA role in HF and the impact of this biomarker on clinical management and risk stratification of HF patients.

Future lines of research on phase angle: Strengths and limitations

Bioelectrical impedance analysis (BIA) is the most widely used technique in body composition analysis. When we focus the use of phase sensitive BIA on its raw parameters Resistance (R), Reactance (Xc) and Phase Angle (PhA), we eliminate the bias of using predictive equations based on reference models. In particular PhA, have demonstrated their prognostic utility in multiple aspects of health and disease. In recent years, as a strong association between prognostic and diagnostic factors has been observed, scientific interest in the utility of PhA has increased. In the different fields of knowledge in biomedical research, there are different ways of assessing the impact of a scientific-technical aspect such as PhA. Single frequency with phase detection bioimpedance analysis (SF-BIA) using a 50 kHz single frequency device and tetrapolar wrist-ankle electrode placement is the most widely used bioimpedance approach for characterization of whole-body composition. However, the incorporation of vector representation of raw bioelectrical parameters and direct mathematical calculations without the need for regression equations for the analysis of body compartments has been one of the most important aspects for the development of research in this area. These results provide new evidence for the validity of phase-sensitive bioelectrical measurements as biomarkers of fluid and nutritional status. To enable the development of clinical research that provides consistent results, it is essential to establish appropriate standardization of PhA measurement techniques. Standardization of test protocols will facilitate the diagnosis and assessment of the risk associated with reduced PhA and the evaluation of changes in response to therapeutic interventions. In this paper, we describe and overview the value of PhA in biomedical research, technical and instrumental aspects of PhA research, analysis of Areas of clinical research (cancer patients, digestive and liver diseases, critical and surgical patients, Respiratory, infectious, and COVID-19, obesity and metabolic diseases, Heart and kidney failure, Malnutrition and sarcopenia), characterisation of the different research outcomes, Morphofunctional assessment in disease-related malnutrition and other metabolic disorders: validation of PhA with reference clinical practice techniques, strengths and limitations. Based on the detailed study of the measurement technique, some of the key issues to be considered in future PhA research. On the other hand, it is important to assess the clinical conditions and the phenotype of the patients, as well as to establish a disease-specific clinical profile. The appropriate selection of the most critical outcomes is another fundamental aspect of research.

Phase Angle and Handgrip Strength as Predictors of Clinical Outcomes in Hospitalized COVID-19 Patients

Phase angle (PhA) and muscle strength are predictors of clinical outcomes in critically ill patients. Malnutrition may affect body composition measurements. The aim of this prospective study was to investigate the association between PhA and handgrip strength (HGS), and clinical outcomes in hospitalized COVID-19 patients. The study included a total of 102 patients. Both PhA and HGS were measured twice, within 48 h of hospital admission and on the 7th day of hospitalization. The primary outcome was the clinical status on the 28th day of hospitalization. Secondary outcomes included the hospital length of stay (LOS), the concentrations of ferritin, C-reactive protein and albumin, oxygen requirements and the severity of pneumonia. A one-way analysis of variance (ANOVA) test and Spearman rS correlation coefficient were used for statistical analysis. No differences were found for PhA [on day 1 (p = 0.769) and day 7 (p = 0.807)] and the primary outcome. A difference was found between HGS on day 1 and the primary outcome (p = 0.008), while no difference was found for HGS on day 7 (p = 0.476). Body mass index was found to be associated with the oxygen requirement on day 7 (p = 0.005). LOS was correlated neither with PhA (rs = −0.081, p = 0.422) nor with HGS (rs = 0.137, p = 0.177) on the first day. HGS could be a useful indicator of clinical outcomes in COVID-19 patients, while PhA does not seem to have a clinical impact. However, further research is needed to validate the results of our study.