Phase angle of bioimpedance at 50 kHz is associated with cardiovascular diseases: systematic review and meta-analysis

The phase angle of bioimpedance is an important prognostic tool in clinical practice. The aim of this study was to investigate the association between phase angle and cardiovascular diseases. Electronic searches were carried out on MEDLINE, EMBASE, Cochrane, SCIELO, LILACS, CINAHL, Scopus, and the Web of Science. The PECO was "P" adults over 18 years of age, "E" the presence of cardiovascular disease, "C" absence of cardiovascular disease, and "O" phase angle values. The phase-angle means difference (MD) was analyzed separately by sex. Subgroup metanalysis with age, body mass index, and heart failure disease and meta-regressions were analyzed with random-effects models. Sensitivity analysis was performed considering only studies with high quality. The heterogeneity among studies was assessed using the Q-Cochran test and I² statistics. Four-hundred-thirty-nine articles were identified, and 22 studies were included in this systematic review, totaling 10.010 participants. Eight studies met the criteria for the meta-analysis, involving 2164 participants. The phase angle (PA) was measured at 50 kHz frequency in all studies. Individuals with cardiovascular disease had a smaller PA compared to the control group, for both males (MD -0.70; 95% CI -1.01 to -0.39) and females (MD -0.76; 95% CI -1.39 to -0.13). In the sensitivity analysis, in men, the quality of studies (P < 0.01), and in women, heart failure (P < 0.01) was significantly different between groups.The values of the phase angle were lower in individuals with cardiovascular disease than in control subjects. This result reinforces the importance of this tool in clinical practice, highlighting its potential to assess health status. Registration: The systematic review protocol was registered in the PROSPERO database as CRD42020164178.