Phase angle and metabolic equivalents as predictors of frailty transitions in advanced age

The aim of this prospective study was to investigate whether two cellular and metabolic health indices, phase angle (PhA)and metabolic equivalents (METs), can predict changes in frailty states in fit community-dwelling older people. A sample of 118 individuals aged ≥65 years who attended a twice-weekly mild fitness program of aerobic and/or resistance exercises was enrolled in the study. At baseline and after three years, individuals underwent a clinical examination, biochemical determinations, bioelectrical impedance analysis, body composition assessment with dual energy X-ray absorptiometry, physical performance tests, and frailty and sarcopenia assessment. In 78 participants was executed indirect calorimetry, too. Based on frailty transitions during the follow-up between non-frailty, pre-frailty and frailty, participants were categorized as improved, stable (non-frail or pre-frail), and worsened or remaining frail. The chances to experience different frailty changes by baseline PhA and METs were explored through multinomial regression analysis and expressed as odds ratios (OR)and 95% Confidence intervals (95%CI). During the follow-up, 8 participants improved in frailty status, 84 were stable and 26 worsened or remained frail. For each one-unit increase in PhA, the odds of improving in frailty increased by 4.53 times (95%CI:1.18–17.46); while for each one-unit increase in METs, the odds of worsening in frailty decreased by 65% (95%CI:0.16–0.79). PhA and METs may be indirect measures of functional reserve, with lower values being potential biomarkers of evolving frailty.