PD004 - YOUNG-ADULT-BASED BIVA REFERENCE STANDARDS AND MINIMAL PHASE ANGLE DERIVED FROM A NATIONWIDE JAPANESE DATASET: THE CANVAS PROJECT

PD004

YOUNG-ADULT-BASED BIVA REFERENCE STANDARDS AND MINIMAL PHASE ANGLE DERIVED FROM A NATIONWIDE JAPANESE DATASET: THE CANVAS PROJECT

K. Maeda^1,2,*, J. Ueshima^2,3, Y. Saino⁴

¹Nutrition Therapy Support Center, Aichi Medical University Hospital, Nagakute, ²Department of Geriatric Medicine, National Center for Geriatrics and Gerontology, Obu, ³Department of Nutritional Service, NTT Medical Center Tokyo, ⁴Department of Clinical Nutrition, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan

Rationale: Bioelectrical impedance vector analysis (BIVA) requires population-specific tolerance ellipses, yet no reference has been built exclusively from young adults representing the physiological optimum. We aimed to develop and validate sex-specific BIVA reference ellipses and to propose a minimal reference phase angle (PhA) using nationally representative Japanese data.

Methods: Anthropometric profiles of 677 individuals aged 20–39 years from the 2019 Japanese national nutrition survey were replicated across 20 synthetic datasets. Impedance data from 11,364 healthy young adults were assigned via hybrid hot-deck and Bayesian predictive matching. Sex-specific 50%, 75%, and 95% tolerance ellipses were generated on the R/H–Xc/H plane and pooled via Rubin's rules with bootstrap estimation. Internal consistency was quantified by pairwise Jaccard overlap and Cronbach's α; cross-validity by observed coverage; and construct validity by age-, BMI-, and muscle-mass-stratified vector migration.

Results: Jaccard indices exceeded 0.90 with Cronbach's α ≥0.98 in each sex, indicating excellent reproducibility. Observed coverage approximated nominal levels (95% ellipse: men 94.4%, women 94.1%). For the 95% ellipse, centre coordinates were 333.5 (R/H) and 36.1 (Xc/H) Ω·m⁻¹ for men and 442.2 and 38.8 Ω·m⁻¹ for women; semi-major axes were 115.8 and 125.2 Ω·m⁻¹; semi-minor axes were 7.73 and 8.87 Ω·m⁻¹. Age-stratified analyses showed systematic downward migration of Xc/H, and muscle-mass indices showed coherent leftward shifts along R/H, confirming construct validity. Minimal reference PhA for the 95% ellipse was 4.73° for men and 3.85° for women.

Conclusion: We established the first BIVA tolerance ellipses anchored to nationally representative young-adult data and introduced minimal reference PhA as a clinically interpretable indicator. Prospective validation across diverse populations is needed.

Disclosure of Interest: None declared