The aim of this study was to determine sensibility, specificity and level of association between two indicators of fat mass excess among women. Sixty-five women (aged 50-77 years) participated in the study. The mean values for the group were 70.3 ± 11 kg for body mass and 158.0 ± 5.5 cm for height. The body mass index (BMI) and the reciprocal of ponderal index (RPI) were registered. The percentage of body fat, estimated by the dual-energy X-ray absorptiometry (%BF DEXA), was used as the gold standard measure. Data analyses consisted of descriptive statistics, Pearson's linear correlation and the Kappa index. The mean scores for BMI, RPI and %BF DEXA were 28 ± 4.2 kg.m-2, 38 ± 1.9 cm.kg-1/3 and 38.1 ± 6.0%, respectively. High prevalence of fat mass excess was observed, regardless the method (%BF DEXA = 89.2%, > 28%, RPI = 83.1% and BMI = 73.8%). Pearson's linear correlation coefficients were both significant (p < 0.01) for %BF DEXA and RPI (r = -0.76) and %BF DEXA and BMI (r = 0.72). The Kappa index showed an association of 0.31 between the %BF DEXA and BMI, and of 0.48 between %BF DEXA and RPI. The anthropometric indicators showed high sensitivity and specificity values (79.3% and 71.4% for BMI; 90% and 71.4% for RPI, respectively). The ROC analysis showed areas under the curve of 0.80 for BMI and 0.83 for RIP, which did not differ significantly (p < 0.05). The cutoff points of 26.2 kg.m-2 for BMI and 39.3 cm.kg-1/3 for RPI presented the best relationship between sensitivity and specificity in determining fat mass excess. Therefore, it is concluded that both BMI and RPI do not differ in identifying fat mass excess, and they have high sensibility and specificity in assessing fat excess in women over 50 years of age.
Body mass index; Reciprocal of ponderal index; Obesity; Overweight; Middle-aged women
