Single prediction equation for bioelectrical impedance analysis in adults aged 22-59 years.

The purpose of this study was to validate a single bioelectrical impedance analysis (BIA) equation in healthy Indian subjects aged 22-59 years with a body mass index (BMI) between 16.8 and 47.3 kg m⁻². Healthy subjects (34 men and 30 women) were measured by two methods: bone mineral content (BMC) was measured by a commercial body composition analyser and bioelectrical impedance at various frequencies was measured by a newly developed bioelectrical impedance measurement system. As correlations were high and prediction error was low, a single equation was developed using all subjects as follows: BMC = -3.5268 + (0.0279  x  h) + (0.0145  x  w) + (184  x  (h²/Z(body50)))-(1.08  x  (w x  h²/Z(body6.25)))-(0.0032  x  (age))-(0.103  x  (sex); men = 1, women = 0). BMC measured from commercial instrument InBody720 was 2.552 ± 0.457 kg. BMC predicted by equation was 2.554 ± 0.447 kg (R = 0.976, adjusted R² = 0.948, standard error of estimate = 0.104 kg, total error = 0.09987 kg). The results of this study show that the newly developed multi-frequency bioelectrical impedance measurement system with the single prediction BIA equation can be used in screening the subjects suspected with osteoporosis and for follow-up study of the patient under the therapy for osteoporosis. For validation of commercial instrument InBody720, BMC of 22 healthy subjects was measured by InBody720 and dual-energy X-ray absorptiometry. High correlation (R = 0.9531) and low error (total error = 0.0913 kg) was found between these two methods.