Body mass index and fat free mass index in obstructive lung disease in Korea

To investigate the relationship between body mass index (BMI), fat free mass index (FFMI) and obstructive lung disease in Korea.

Based on a large population-based, nationwide survey conducted in Korea, 822 subjects with airway obstruction and the same number of healthy control subjects were selected. Spirometry and dual-energy X-ray absorptiometry were used for analysis.

Subjects with airway obstruction had a lower mean BMI and FFMI than the control group (23.6 vs. 23.9 kg/m(2) for BMI, P = 0.015 and 17.2 vs. 17.5 kg/m(2) for FFMI, P = 0.013); the BMI (P < 0.001) and FFMI (P < 0.001) values decreased significantly in subjects with severe airway obstruction. The proportion of subjects who were underweight or who had a low FFMI was significantly higher in the severe airway obstruction group (P < 0.001). The decrease in FFMI was more prominent in the lower extremities, followed by the upper extremities and the trunk. Subjects who were underweight had significantly lower one-second forced expiratory volume (FEV1; P = 0.001) and FEV1/forced vital capacity values (P < 0.001).

We suggest that lower BMI and FFMI are associated with degree of airway obstruction and that the assessment of BMI and body composition is necessary in patients with severe airway obstruction.