Accuracy og three novel predictive methods for measurement of fat mass in healthy older subjects with different degree of body mass index compared to four body composition techniques

This study evaluated the agreement of novel anthropometric equations and established indirect methods (skinfold thickness and bioimpedance analysis) with reference methods [dual X-ray absorptiometry (DXA) and air displacement plethysmography (ADP)] for fat mass assessment (FM) in older subjects. Methods Forty subjects (M/F = 15/25, age = 61–84 years, BMI = 18–37 kg/m2) were recruited. The agreement of the following predictive equations was evaluated: body adiposity index (BAI), BAI-Fels and Clı´nica Universidad de Navarra-body adiposity estimator (CUN-BAE). Results BAI estimates were comparable to DXA (D ± 2SD = 0.4 ± 6.0 kg, p[0.05) but not to ADP (D ± 2SD = -2.8 ± 7.2 kg, p.001); BAI-Fels estimates were comparable to DXA (D ± 2SD = 0.8 ± 5.5 kg, p[0.05) but not to ADP (D ± 2SD = -4.0 ± 6.9 kg, p.001). The difference between CUN-BAE and ADP was not significant (D ± 2SD = -0.4 ± 5.6 kg, p[0.05), whereas it significantly overestimated DXA (D ± 2SD = 2.8 ± 5.4 kg, p.001). ADP significantly overestimated FM compared to DXA (D ± 2SD = 3.2 ± 5.4 kg, p.001) and the measurement bias was significantly correlated with BMI in men (p = 0.004). Conclusions The accuracy of the three anthropometric indexes is dependent on the choice of the reference method. The variability of the FM estimates was large and these indexes cannot be recommended for the assessment of FM in older subjects