# Associations of phase angle and its change with all-cause mortality among community-dwelling older Japanese adults

## TL;DR

Lower phase angle and greater decline in phase angle over five years are linked to higher mortality risk in older Japanese adults.

## Contribution

This study is among the first to link changes in phase angle over time with mortality risk in older adults.

## Key findings

- The lowest phase angle quartile had a 49% higher mortality risk compared to the highest quartile.
- Greater decline in phase angle beyond age-related expectations was associated with a 42% higher mortality risk.
- Phase angle may serve as a noninvasive predictor of mortality risk in older adults.

## Abstract

Phase angle measured by bioimpedance is considered to reflect muscle quality and nutritional status. This study investigated the associations of phase angle and its 5-year change with all-cause mortality among community-dwelling older Japanese adults. A total of 1,291 Japanese adults aged ≥65 years with phase angle measured in 2012 were followed-up for a median of 10.3 years. Participants were divided into age-and sex-specific quartiles of phase angle and into quartiles of 5-year change in phase angle beyond standard age-related decline, defined as the difference between actually measured and estimated values from the linear regression line between phase angle values measured in 2007 and 2012. Hazard ratios (HRs) for all-cause mortality were estimated using Cox proportional hazards models. During follow-up, 347 participants died. The lowest quartile of phase angle showed a higher risk of all-cause mortality compared with the highest quartile after multivariable adjustment (HR 1.49, 95% CI 1.10–2.02). A similar trend was observed for 5-year change in phase angle beyond age-related decline (HR 1.42, 95% CI 1.03–1.97). Lower phase angle and greater decline beyond age-related expectations were associated with increased mortality risk. Phase angle may provide a simple, noninvasive measure of mortality risk in older adults.

The online version contains supplementary material available at 10.1038/s41598-026-35266-2.