Indexation of left ventricular mass in adults with a novel approximation for fat-free mass

Background Indexation to fat-free mass (FFM) seems to be the best option fo r adjusting left ventricular (LV) mass. However, measurements of FFM are fr equently not available, Objectives To define the relation of FFM with commonly available anthropome tric measures in order to derive an approximation formula of FFM that can b e used for valid indexation of LV mass. Subjects and methods A total of 1371 subjects from a community survey were examined by echocardiography to measure LV mass and by bioelectrical impeda nce analyses (BIA) for the determination of FFM, An approximation of FFM wa s generated in a healthy subgroup of 213 men and 291 women by non-linear re gression techniques. Results Compared with body height, height(2.0), height(2.7), (the superscri pts following weight and height are raised powers used as a more appropriat e method for indexing LV mass) or body surface area, FFM measured by BIA in the healthy subgroups was best predicted by gender-specific equations of t he form: FFM = 5.1 X height(1.14) X weight(0.41) for men and FFM = 5.34 X height(1.47) X Wejght(0.33) for women, In the healthy reference group, indexation of LV mass for BIA-determined FF M and approximated FFM (FFMa), respectively, equally eliminated gender diff erences in LV mass and markedly reduced the influence of body mass index wi thout affecting the associations between blood pressure and LV mass. Valida tion of FFMa in two independent population-based samples, aged 52 to 67 yea rs, of the same source population confirmed that LV mass indexed by FFMa pr oduced results that were highly consistent with those obtained with indexat ion by BIA-determined FFM, Conclusions We propose a novel approximation of FFM based on exponentials o f body height and weight. It performed well in the indexation of LV mass in middle-aged men and women of this study, Evaluation of the equation in oth er populations should be awaited before its use is recommended in situation s where direct determination of FFM is not possible. (C) 2001 Lippincott Wi lliams & Wilkins.