Body composition analysis using bioelectric impedance in Bissau: reproducibility and level of agreement between two available devices.

Introduction: the need to correctly measure and follow body composition as a simple disease prevention metric is important, especially where the healthcare infrastructures are poor. The variety of inexpensive devices available for this purpose is large. However, it is imperative to validate them in relation to the gold standard method, dual-energy absorptiometry X-ray (DEXA). In low-income countries, DEXA measurements aren't available. Thus, easy-to-use, and accurate devices are indispensable. In Guinea-Bissau, two relatively inexpensive, bioelectrical impedance scales, simple to use, are available. However, their accuracy has not been assessed in this setting. The study compares the level of agreement in measurements between, the Tanita® BC-545 and the Omron Karada Scan BF511, in adult volunteers.

Methods: volunteers grouped for athletic and sports modalities at stadiums and sports facilities in Bissau were included. All anthropometric measurements were done in both devices. For statistical analysis, we created Bland-Altman plots to assess their level of agreement.

Results: the study included 274 participants, mean age 27.4 years, 214 (78%) males. For body fat, the median between the Omron and Tanita measures was 2.6 and the interquartile was 5.2. The Omron measured median body mass index, -0.3 kg/m² and 0.8 kg/m² of interquartile below that of the Tanita. For visceral fat, the Omron measured 1% of median and an interquartile of 2% above that of the Tanita. For skeletal muscle, the Omron median measured 11.3% and 11.4 % of interquartile below that of the Tanita. The intra-class correlation coefficient (ICC) for body fat (BF), body mass index (BMI) and skeletal muscle (SM) was 0.99 and for VF it was 1.00 on both devices.

Conclusion: the results indicate a good level of agreement between the two devices. In resource-limited settings, the Omron is likely a reasonable substitute for more expensive body composition devices.