Interpreting longitudinal spirometry: Weight gain and other factors affecting the recognition of excessive FEV 1 decline

Background Excessive FEV 1 loss in an individual or a group can reflect hazardous exposures and development of lung disease. However, multiple factors may affect FEV 1 measurements. Methods Using medical screening data collected in 1884 chemical plant workers between 1973 and 2003, the influence of multiple factors on repeated measurements of FEV 1 was examined. Results The FEV 1 level was associated with age, height, race, sex, cigarette smoking, changes in body weight, and spirometer model. After controlling for these factors, longitudinal FEV 1 decline averaged 23.8 ml/year for white males; an additional loss of 8.3 ml was associated with one pack‐year smoking and 5.4 ml with a one pound weight gain. Depending on the spirometer model, FEV 1 differed by up to 95 ml. Conclusions The study results provide quantitative estimates of the effect of specific factors on FEV 1 , and should be useful to health professionals in the evaluation of accelerated lung function declines. Am. J. Ind. Med. 52:782–789, 2009. © 2009 Wiley‐Liss, Inc.