Abstract

Background: Some histopathologic patterns of bronchiolar disease may be relatively unique to a specific clinical entity, such as respiratory bronchiolitis caused by cigarette smoking and toxic fumes i.e. sulfur mustard (SM). The aim of this study was to determine the trend of pulmonary function indices in SM-exposed patients with the diagnosis of bronchiolitis obliterans. Materials and Methods: In this retrospective cohort study, 407 cases were evaluated. Patients were divided into 4 groups according to the time period from performing PFT: 1-3, 4-6, 7-10 and more than 10 years. The amounts of these changes amongst four PFT interval groups were compared by analysis of variance test. In addition, we used linear regression analysis to create a linear model of changes for each PFT index. Results: The following equations imply a correlation between decrease in PFT indices and interval between the two tests plus index value of baseline PFT. 1: FVC )= -2.23 - (0.76 T)-(0.23 FVC1 ), 2: FEV1 )=-1.43 - (0.95 T)-(0.10 FEV11 ), 3: PEF )= -0.91 - (1.07 T)-(0.14 PEF1 ). Conclusion: Better understanding of the nature of bronchiolitis obliterans, helps improve the treatment of this disease. Our study suggests a pattern of decline in pulmonary function indices directly proportional to the percentage of each index in the baseline PFT which was apparent during a 10-year observation period. © 2007 NRITLD, National Research Institute of Tuberculosis and Lung Disease, Iran.