[Agreement analysis and result calibration by ordinary least product regression between bioelectrical impedance analysis and dual energy X-ray absorptiometry].

Objective To analyze agreement of body fat percentage measured by bioelectrical impedance analysis(BIA) and dual energy X-ray absorptiometry(DXA) in Chinese adults, and to calibrate BIA measurement by ordinary least product regression(OLP). Methods Volunteers aged 18-65 were recruited to measure total body fat percentage and trunk fat percentage by BIA(Tanita BC-601 F) and DXA(Hologic Discovery QDR), respectively. Agreement between the two methods was compared by OLP. Bootstrap method was used to do the internal validation of the calibration equation. The calibration effect was verified by the agreement analysis of the calibrated BIA result and the DXA result. Results Before calibration, all 95%CIs of the intercepts of the OLP regression lines did not include 0, and all 95%CIs of the slopes of the OLP regression lines did not include 1. 00. After calibration, all 95% CIs of the intercepts of the OLP regression lines included 0, and all 95% CIs of the slopes included 1. 00. Conclusion There are fixed bias and proportion bias between BIA and DXA in measuring total body fat percentage and trunk fat percentage in Chinese men and women. Calibration should be considered when body fat percentage is measured by BIA.