Combined fat mass and fat-free mass indices and lung function among Japanese population: The Tohoku Medical Megabank Community-based Cohort Study.

BACKGROUND

Although fat mass index (FMI) and fat-free mass index (FFMI) affect lung function, FMI and FFMI are not independent of each other since FMI and FFMI were calculated as fat mass and fat-free mass divided by height squared, respectively. We aimed to examine the association of combined FMI and FFMI with lung function.

METHODS

In this cross-sectional study, lung function was evaluated using forced expiratory volume at 1 s and forced vital capacity was measured using spirometry. Both FMI and FFMI were classified into sex-specific quartiles (16 groups). Analysis of covariance was used to assess the associations of combined FMI and FFMI with lung function. The trend test was conducted by stratifying the FMI and FFMI, scoring the categories from 1-4 (lowest-highest), and entering the number as a continuous term in the regression model.

RESULTS

This study included 3,736 men and 8,821 women aged ≥20 years living in Miyagi Prefecture, Japan. The mean FEV

CONCLUSIONS

Higher FMI was associated with lower lung function independent of FFMI; higher FFMI was associated with higher lung function independent of FMI. Reducing FMI and maintaining FFMI might be important for respiratory health.