@article {Nafeesoemed-2021-107680, author = {Asaad Ahmed Nafees and Muhammad Zia Muneer and Sara De Matteis and Andre Amaral and Peter Burney and Paul Cullinan}, title = {Impact of using different predictive equations on the prevalence of chronic byssinosis in textile workers in Pakistan}, elocation-id = {oemed-2021-107680}, year = {2021}, doi = {10.1136/oemed-2021-107680}, publisher = {BMJ Publishing Group Ltd}, abstract = {Objective Byssinosis remains a significant problem among textile workers in low/middle-income countries. Here we share our experience of using different prediction equations for assessing {\textquoteleft}chronic{\textquoteright} byssinosis according to the standard WHO classification using measurements of forced expiratory volume in 1 s (FEV1).Methods We enrolled 1910 workers in a randomised controlled trial of an intervention to improve the health of textile workers in Pakistan. We included in analyses the 1724 (90\%) men who performed pre-bronchodilator spirometry tests of acceptable quality. We compared four different equations for deriving lung function percentage predicted values among those with symptoms-based byssinosis: the third US National Health and Nutrition Examination Survey (NHANES-III, with {\textquoteleft}North Indian and Pakistani{\textquoteright} conversion factor); the Global Lung Function Initiative (GLI, {\textquoteleft}other or mixed ethnicities{\textquoteright}); a recent equation derived from survey of a western Indian population; and one based on an older and smaller survey of Karachi residents.Results 58 men (3.4\%) had symptoms-based byssinosis according to WHO criteria. Of these, the proportions with a reduced FEV1 (\<80\% predicted) identified using NHANES and GLI; Indian and Pakistani reference equations were 40\%, 41\%, 14\% and 12\%, respectively. Much of this variation was eliminated when we substituted FEV1/forced vital capacity (FVC) ratio (\<lower limit of normality) as a measure of airway obstruction.Conclusion Accurate measures of occupational disease frequency and distribution require approaches that are both standardised and meaningful. We should reconsider the WHO definition of {\textquoteleft}chronic{\textquoteright} byssinosis based on changes in FEV1, and instead use the FEV1/FVC.Data are available upon reasonable request.}, issn = {1351-0711}, URL = {https://oem.bmj.com/content/early/2021/11/19/oemed-2021-107680}, eprint = {https://oem.bmj.com/content/early/2021/11/19/oemed-2021-107680.full.pdf}, journal = {Occupational and Environmental Medicine} }