Utility of phase angle from bioelectrical impedance analysis as a disease-related clinical marker in people with dementia: A systematic review and meta-analysis.

BACKGROUND AND AIMS: Dementia, a growing global health challenge, is frequently associated with malnutrition. The phase angle (PhA), derived from bioelectrical impedance analysis, is often clinically associated with composite changes related to the nutritional status. As a reduction in PhA shares common underlying mechanisms with the characteristic pathophysiological changes in dementia, its clinical utility as a surrogate marker for dementia has been proposed; however, this role remains uncertain. We aimed to systematically review and meta-analyze the evidence for PhA as a disease-related clinical marker in people with dementia (PwD).

METHODS

This Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review and meta-analysis was PROSPERO-registered (registration number: CRD420251000592). We searched four major databases for clinical studies reporting PhA in PwD up to March 2025. Two reviewers independently performed study selection, data extraction, and risk of bias assessment. Primary meta-analyses compared whole-body PhA between PwD and healthy controls (HC), and PwD and people with mild cognitive impairment (PwMCI), using the weighted mean difference (WMD). Heterogeneity (I2), publication bias, and evidence certainty assessments, as well as sensitivity and subgroup analyses, were performed.

RESULTS

Of 1941 records identified, 12 studies were included, with 8 eligible for meta-analysis. Whole-body PhA was significantly lower in PwD than in HC (5 studies; 422 PwD, 1296 HC; WMD = -0.90°, 95 % confidence interval [CI]: -1.00 to -0.80; I2 = 0 %). No significant difference was found between PwD and PwMCI (2 studies; 130 PwD, 116 PwMCI; I2 = 82 %), but subgroup analysis by sex showed a significantly lower PhA in males with dementia than those with MCI (WMD = -0.44°, 95 % CI: -0.72 to -0.16). A meta-analysis of upper limb segmental PhA (2 studies) showed no significant difference, with high heterogeneity (I2 = 91 %).

CONCLUSION

PhA may be a useful clinical surrogate marker for PwD, as it is potentially associated with composite changes related to nutritional status. Its noninvasive and easy-to-measure nature makes it practical for PwD. Nevertheless, this evidence is primarily based on cross-sectional studies. Further high-quality prospective and interventional studies are crucial to establish its clinical significance and utility in the nutritional management of PwD.