Validation of respiratory questionnaire for lung function assessment among an occupational group of textile workers in Pakistan

Objective: To determine the association of spirometric lung pattern with respiratory symptoms and to validate the American Thoracic Society respiratory questionnaire for lung function assessment among textile workers.Methods: This cross-sectional survey was conducted from August to December 2009 among adult textile workers of Karachi. Data was collected through the American Thoracic Society Division of Lung Disease respiratory questionnaire and the lung function was assessed by using a spirometer. Results of three acceptable readings of spirogram were recorded and the best of the three readings was used for analysis. SPSS 19 was used for data analysis.Results: There were 372 participants in the study with an overall mean age of 27±8.5 years. In linear regression analysis, forced expiratory volume in one second for workers who had chronic cough was -829.1 (confidence interval: -1273.1, -385.2), chronic wheeze -168.8 (confidence interval: -319.3, -18.2) and shortness of breath grade 2 -215.6 (confidence interval: -387.8, -43.4). In logistic regression model, after adjusting for covariates, odds of reduced percentage predicted forced expiratory volume in one second for workers who had chronic cough was 3.09 (confidence interval: 1.26, 7.56), chronic wheeze 1.98 (confidence interval: 1.05, 3.71) and shortness of breath grade 2 2.07 (confidence interval: 1.05, 4.07), while odds of reduced percentage predicted forced vital capacity for shortness of breath grade 2 was 2.35 (confidence interval: 1.05, 5.21). In logistic regression model 2, for assessing the effect of different combinations of chronic respiratory symptoms, the odds of reduced percentage predicted forced expiratory volume in one second for the combination of cough and wheeze was 2.08 (confidence interval: 1.05, 4.10), cough and shortness of breath grade 2 2.47 (confidence interval: 1.18, 5.18), phlegm and shortness of breath grade 2 2.59 (confidence interval: 1.23, 5.43), cough, wheeze and shortness of breath grade 2 4.64 (confidence interval: 1.97, 10.93)and cough, phlegm, wheeze and shortness of breath grade 2 4.18 (confidence interval: 1.68, 10.37).Conclusions: A combination of chronic respiratory symptoms was best associated with decrements in lung function