Weight change and lung function: Implications for workplace surveillance studies

This study evaluated the relationship between weight change and longitudina l measurement of lung function among 361 men providing at least five pulmon ary function tests. The men in this study were participants in a workplace pulmonary surveillance program for subjects with exposure to refractory cer amic fibers (RCFs) . Occupational and environmental studies are generally d esigned to evaluate factors suspected of causing excess decline in lung fun ction. Failure to adequately account for all significant factors may lead t o erroneous conclusions regarding change in lung function. This study utili zed two different statistical models to evaluate longitudinal changes in a cohort of RCF workers. What was unique to this study was the modeling of lo ngitudinally measured initial weight, weight change, and longitudinal expos ure before and during the period of observation. Results showed a strong re lationship between weight gain and longitudinal loss in lung function that approximated forced vital capacity declines of 16 mL for every kilogram of weight gain per year in both models. This value is comparable or greater in magnitude and significance to other factors known to be inversely related to lung function, such as age and pack-years smoking to time of initial tes ting. In conclusion, weight gain was found to have a significant impact on longitudinal change in lung function. Therefore, weight gain becomes a very important variable that requires consideration whenever longitudinal studi es of pulmonary function are conducted.