Body composition and pulmonary function in the elderly: a 7-year longitudinal study

Objective: To evaluate over a 7-year follow-up period the relationships between changes in body composition, fat distribution and pulmonary function in a sample of elderly men and women. Design: Longitudinal clinical study. Subjects: A total of 47 women and 30 men aged 71.6 +/- 2.3 and 71.7 +/- 2.2 years, respectively, at baseline with body mass index (BMI) values of 24.96 +/- 3.28 and 27.04 +/- 3.35 kg m(-2) were followed for 7 years. Measurements: Body weight, waist circumference, sagittal abdominal diameter (SAD), fat-free mass (FFM) and fat mass as measured by dual energy X-ray absorptiometry (DXA) and forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) by spirometry were evaluated at baseline and after a 7-year mean follow-up. Results: In women as in men there were no significant changes in weight, SAD and BMI. A significant decrease in height and FFM was observed in both women and men. Height-adjusted FEV1 and FVC decreased significantly in women and men over the 7-year follow-up. Changes in SAD were the most powerful predictors of 7-year follow-up of FEV1 and FVC after taking into account, respectively, baseline FEV1 and FVC. Linear regression analysis, performed by using 7-year follow-up lung function variables as dependent variables and changes in body composition variables as independent variables, showed that 1 cm SAD increase predicted a decrease in FEV1 and FVC of 31 and 46 ml, respectively, and 1 kg FFM decrease predicted a decrease in FVC of 38 ml. After subdividing our study population into four categories of change in FFM and SAD, patients with decreased FFM and increased SAD showed the highest probability of having a worsening in FEV1 and FVC. Conclusion: Increase in abdominal fat and FFM decline are significant predictors of lung function decline in the elderly. Old subjects developing both abdominal fat gain and FFM loss show the highest probability of developing worsening in lung function.