Abstract

CACERES, Diana Isabel et al. Variability in bioelectrical impedance assessment of body composition depending on measurement conditions: influence of fast and rest. Nutr. Hosp. [online]. 2014, vol.30, n.6, pp.1359-1365. ISSN 1699-5198.  https://dx.doi.org/10.3305/nh.2014.30.6.7934.

Background: Bioelectrical Impedance Assessment (BIA) is one of the main tools to measure body composition. BIA is recommended in fasting and after 60 minutes of rest; however, this cannot always be guaranteed in healthcare practice. Objectives: To establish the reliability of the body composition parameters assessed with BIA under different physiological conditions: fast + rest, fast + no-rest and no-fast + no-rest in healthy volunteers. Methods: Transversal study including 25 healthy volunteers aged 18-34 (12 men, 13 women). A BIA was performed under three different conditions: 1) fast + 60 minute rest in cubito supino (gold standard), 2) fast + no rest and 3) no fast + no rest. The collected parameters were: lean mass and fat mass (Kg) and body water (in liters and as body weight percentage). The intraclass correlation coefficient (ICC) was applied for the assessment of concordance within the different measurements. Results: Compared to the gold standard, the difference in lean mass means in the condition of fast + no-rest, was -0.15 (DE 1.44) in men and 0.98 (DE 1.36) in women; fat mass decreased in 0.06 (DE 1.55) in men and 0.82 (DE 1.5) in women; ICC ranged between 0.826-0.995 in all comparisons. In the condition of no-fast + no rest, lean mass decreased an average of 0.05 (DE 0.33) in men and it increased 0.62 (DE 0.46) in women; fat mass decreased 0.57 (DE 0.82) in men and 0.46 (DE 0.60) in women; ad ICC ranged between 0.942 and 0.999, except in body water in men, where it was 0.340. Discussion: Although relevant, the differences observed in parameters from BIA when comparing the gold standard condition (fast + rest) with the other conditions (fast + no-rest and no-fast + no-rest) are of little magnitude. In clinical practice, the assessment of body composition allows to take decisions when planning treatment for patients with a poor physical condition. Conclusions: The reliability of the parameters acquired via BIA within different physiological conditions of fast and rest is excellent (CCI >0.75) in healthy adults aged 19-34. Although general recommendations on the use of BIA devices must be kept in place, the conditions of the performance could be modified according to the context and assuming a small difference of little clinical relevance.

Keywords : Bioelectrical impedance; Body composition; Reliability; Intraclass correlation coefficient.

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