Bioelectrical Impedance Analysis (BIA) and Phase Angle Introduction

T164, A0969, page 1442, journal of the American Society of Nephrology, September 1996, Volume 7, #9 Link not available Abstract: We performed a cross-sectional study of BIA (Bioelectrical impedance analysis, BIA 101-Q, RJL Systems, Clinton Township, MI) in 3009 HD (hemodialysis) patients with follow-up to 12 (median 8) months to evaluate the relation between impedance and survival. 296 deaths were documented over the study period; patients were censored at transplantation or if lost to followup. Mean (± SD) age was 60.5 ± 15.5 years, 47% were females, 47% AfricanAmerican, and 36% diabetic. Dialysis vintage was 3.8 ± 3.7 years. Mean reactance (Xc) was 40.9 ± 13.8 ohms; mean resistance (R) was 497.7 ± 99.0 ohms. The mean Xc/R ratio 0.084 ± 0.030; Xc/R was directly correlated with albumin (r=0.24), pre-albumin (r=0.27), and creatinine (r=0.40), and inversely correlated with age (r= -0.33) and Quartile's index (r= 0.15). Xc/R was significantly higher in men Africa Americans, and non-diabetics (P< 0.0001 compared with women, Caucasians, and diabetics, respectively). To obviate linearity assumptions, Xc/R was ranked into quintiles, and the relative risks of death (RR) and 95% confidence intervals (95% CI) within each quintile were estimated from proportional hazards regression, with and without covariate We performed a cross-sectional study of BIA (Bioelectrical impedance analysis, BIA 101-Q, RJL Systems, Clinton Township, MI) in 3009 HD (hemodialysis) patients with follow-up to 12 (median 8) months to evaluate the relation between impedance and survival. 296 deaths were documented over the study period; patients were censored at transplantation or if lost to followup. Mean (± SD) age was 60.5 ± 15.5 years, 47% were females, 47% AfricanAmerican, and 36% diabetic. Dialysis vintage was 3.8 ± 3.7 years. Mean reactance (Xc) was 40.9 ± 13.8 ohms; mean resistance (R) was 497.7 ± 99.0 ohms. The mean Xc/R ratio 0.084 ± 0.030; Xc/R was directly correlated with albumin (r=0.24), pre-albumin (r=0.27), and creatinine (r=0.40), and inversely correlated with age (r= -0.33) and Quartile's index (r= 0.15). Xc/R was significantly higher in men Africa Americans, and non-diabetics (P< 0.0001 compared with women, Caucasians, and diabetics, respectively). To obviate linearity assumptions, Xc/R was ranked into quintiles, and the relative risks of death (RR) and 95% confidence intervals (95% CI) within each quintile were estimated from proportional hazards regression, with and without covariate adjustment. Survival in patients within the upper three quintiles of Xc/R; The RR in the two lowest quintiles was 2.7 (95% CI 1.1 to 2.2, P=0.009), respectively. After adjustment for age, sex, race, diabetes, albumin, creatinine, and urea reduction ratio, the RR in the lowest quintile was 1.5 (95% CI 1.2 to 2.1, P=0.003). Results were similar when Xc and R were adjusted for body stature. Conclusion: Xc/R is correlated with biochemical surrogates of nutritional status in hemodialysis patients, and provides prognostic power even after adjustment for case mix and laboratory variables. Longer-term follow-up and longitudinal assessment of Xc/R will be required to determine the optimal role for BIA in HD patient assessment. Phase angle from bioelectrical impedance analysis remains an independent predictive marker in HIV-infected patients in the era of highly active antiretroviral treatment Schwenk A, et al; American Journal of Clinical Nutrition, 2000 Aug; 72(2):496-