Challenges in Longitudinal Spirometry Data in Occupational Medicine: Spirometry Indices during Five Consecutive Years and its Causative Factors

BACKGROUND: Respiratory illnesses caused by occupational exposure have the most negative effects on the workers’ health status in workplaces. In occupations with a high likelihood of labor-induced pulmonary diseases, a periodic spirometry test is usually used to monitor occupational lung function and prevent occupational respiratory diseases. Monitoring workers exposed to occupational pulmonary diseases is widely done using forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) for early diagnosis of obstructive pulmonary and lung diseases. We assessed the usefulness of longitudinal data of periodic spirometry tests in a sulfate production industry. MATERIALS AND METHODS: In this longitudinal study, 212 individuals working in a sulfate production industry near Tehran were examined. Demographic data and information, such as FEV1, FVC, FEV1%, FVC%, and FEV1 / FVC ratio were obtained from 2009 to 2013. Data were analyzed using the SPSS software version 21. The one-way analysis of variance (ANOVA) and repeated measures ANOVA for data analysis. RESULTS: The results showed that the variation of the spirometry parameters over 5 years was significant. The factors studied not only decreased in some years but also increased in comparison with the previous year. Also, the average FEV1 and FVC and also FEV1 / FVC significantly was different at different time points [F(2.864, 590.029)= 27.269, P < .0001], [F(2.910, 599.546)= 38.239, P < .0001], and [F(3.257, 671.019)= 13.351, P < .0001]. CONCLUSION: The best spirometry tests, not only acceptable tests, are important in longitudinal spirometry evaluations. There is no systematic supervision on spirometry tests in Iran and the results of this study reflect a serious need for such supervision.