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Bioelectrical impedance phase angle and the mortality in critically ill children
Jiongxian Yang1, Jie Zhang2, Jun Liu2
1Department of Health Care Center, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China.
Insights
Phase angle (PhA), measured by bioelectrical impedance analysis (BIA), predicts longer PICU length of stay and increased mortality in critically ill children. Low PhA (<3.1°) indicates a poorer prognosis, highlighting its role as a prognostic indicator.
Area of Science:
- Critical Care Medicine
- Pediatric Nutrition Assessment
- Bioelectrical Impedance Analysis (BIA)
Background:
- Phase angle (PhA) from BIA is a sensitive clinical nutrition marker.
- Its prognostic value in pediatric critical care is under-researched.
- This study explores PhA's association with outcomes in critically ill children.
Purpose of the Study:
- To investigate the relationship between admission PhA and PICU length of stay (LOS).
- To assess PhA as a predictor of 60-day mortality in critically ill pediatric patients.
- To establish a critical PhA cutoff value for predicting outcomes.
Main Methods:
- Bioelectrical impedance analysis (BIA) performed within 72 hours of admission for 205 pediatric patients.
- Kaplan-Meier survival analysis and multivariate Cox regression to assess 60-day mortality.
- Youden's index and ROC curves used to determine the optimal PhA cutoff value.
Main Results:
- A PhA cutoff of 3.1° was identified, with lower PhA associated with significantly higher mortality (p<0.0001).
- Patients with PhA <3.1° had longer PICU LOS (HR 1.871, p=0.000) and hospital LOS.
- PhA and PIM-2 score were independent predictors of 60-day mortality.
Conclusions:
- Low phase angle (<3.1°) in pediatric ICU patients is linked to prolonged PICU stays and increased mortality risk.
- PhA serves as a valuable prognostic indicator in critically ill children, beyond its role in nutritional assessment.
- Routine PhA measurement can aid in risk stratification and management of pediatric ICU patients.
Background:
Phase angle (PhA) is a variable obtained from bioelectrical impedance analysis (BIA). It is highly sensitive and specific and is commonly used in clinical nutrition assessment. Recently, PhA has shown promise in predicting clinical outcomes, especially as a new indicator of mortality, but its use in pediatric research is limited. This study aims to investigate the association between PhA measured at admission using BIA and PICU length of stay (LOS) and 60-day mortality in critically ill children and adolescents.
Methods:
A consecutive series of pediatric patients in the PICU underwent BIA measurements within 72 h of admission. All patients met the inclusion and exclusion criteria. Patient demographics, anthropometric measurements, pediatric index of mortality 2 score (PIM-2), and laboratory exams were recorded. Kaplan-Meier (K-M) survival curves were constructed based on the critical PhA value to assess differences in survival status within the 60-day window. Multivariate cox regression model was employed to illustrate the relationship between PhA and 60-day mortality rates. The Youden's index method was used to identify the critical cut-off value for PhA in relation to mortality rates. ROC curves provided the area under the curve (AUC) and a 95% confidence interval (CI).
Results:
A total of 205 pediatric patients (118 boys) were included, with a mean age of 9.2 years (±6.0). Survival curves indicated a cutoff value of 3.1°, with higher survival in patients with PhA ≥3.1° compared to those with PhA <3.1° (F = 10.51, p < 0.0001). The area under the ROC curve was 0.70, with a sensitivity of 0.65 and specificity of 0.72. Total hospital LOS was longer in the PhA <3.1° group compared to the PhA ≥3.1° group (p = 0.000). The PhA <3.1° group had a longer PICU LOS (adjusted for age and sex, HR 1.871, p = 0.000, log-rank test, p = 0.000). PhA and PIM-2 were two independently significant correlated variables (p < 0.05) for the 60-day mortality rate in this study.
Conclusion:
Low PhA in patients is associated with longer PICU LOS and an increased risk of PICU patient mortality. PhA not only serves as an indicator for monitoring pediatric nutrition but also as a prognostic indicator for PICU patients.
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