Phase angle and body composition as determinants of functional capacity in hemodialysis.

Abstract

Introduction: Hemodialysis (HD) induces severe stress that alters patients' nutritional status and physical autonomy. Phase angle (PA) and the Barthel Index (BI) allow for a comprehensive assessment of this impact. The aim of this study was to determine the association between PA, body composition, and functional capacity, and to identify specific phenotypic profiles using K-means clustering.

Materials and Methods: A retrospective, observational study (February 2021 – October 2022) involving 127 HD patients. PA, fat mass (FAT), lean tissue mass (LTM), and body cell mass (BCM) were measured using pre-dialysis multifrequency bioelectrical impedance analysis (BIA), while functionality was assessed using the BI. Pearson correlation and K-means clustering (k=3) analyses were applied, supported by principal component analysis (PCA).

Results: PA correlated positively with BI (r = 0.39, p < 0.001) and BCM (r = 0.61, p < 0.001), and negatively with FAT (r = -0.35, p = 0.002). The K-means model identified three distinct profiles:

Cluster 0 (High Risk): Older patients (65.9 ± 10.2 years) with low PA (3.57 ± 0.6°), higher adiposity (42.25 ± 8.4%), lower LTM (37.11 ± 6.9 kg), and lower functionality (BI: 75.45 ± 12.8). Cluster 1 (Preserved): individuals with high PA (5.5 ± 0.7°), low FAT (25.54 ± 6.2%), high LTM (62.18 ± 8.7 kg), and functional independence (BI: 94.17 ± 6.9).
Cluster 2 (Intermediate): Lower mean age (48.35 ± 11.4 years), mixed composition (FAT: 36.57%, LTM: 47.91 kg), moderate PA (4.69 ± 0.8°), and high functionality (BI: 97.38 ± 2.6).

Conclusions: PA and body composition are significantly associated with functionality. Automated cluster-based segmentation optimizes the identification of subgroups at functional and nutritional risk, enabling the guidance of personalized dietary interventions to preserve quality of life.