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Airways Obstruction From Asbestos Exposure: Possible Confounding Factors
Reader variability in classifying asbestosis from chest radiographs, particularly between ILO profusion categories of which the most critical is between negative and positive (ILO profusion 0/1 vs 1/0), could enhance or reduce differences in pulmonary functions. Using one consistent reader minimizes this variability. Interpreting an abnormal radiograph as normal, thereby placing a subject with asbestosis […]
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Airways Obstruction From Asbestos Exposure: Cautions
Few physiologic studies of asbestosis have attempted to integrate structure and function or localize the principal target of the disease. Becklake et al, nearly two decades ago, showed midexpiratory flow and FEVi limitations in men exposed to asbestos and greater reductions in those with asbestosis. Jodoin et al, finding that midflows and FEVi decreased early […]
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Airways Obstruction From Asbestos Exposure: Discussion
Asbestos without personal cigarette smoking caused progressive asbestos lung disease. Its course has been approximated from these observations. Analysis by difference in means, differences in residuals (observation minus group mean), and by regression agreed that physiologic abnormalities worsened as asbestosis was recognized and increased in severity on radiographs. First, with asbestos exposure alone, was reduced […]
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Airways Obstruction From Asbestos Exposure: Results
The statistical significance of group differences in means and in mean residuals were virtually identical, with only five differences in 30 comparisons. Three of these were in ex-smokers whose group variances (SDs) are invariably larger. As the profusion of opacities increased from 0/0 to 3/2 in as men who had never smoked cigarettes FVC, FEVi, […]
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Airways Obstruction From Asbestos Exposure: Ex-smokers
For current smokers all comparisons of pulmonary function tests as differences from predicted for asbestos exposed vs never exposed were significant, including FVC (middle section of Table 3). Thus, comparison of differences in smokers with asbestosis to differences in those never exposed to asbestos were significant for the same parameters as were the* comparisons as […]
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Airways Obstruction From Asbestos Exposure: Residuals for Never Smokers
When men with pulmonary asbestosis with 30.6 years of asbestos exposure (column C), were compared with the unexposed men (column A), flows (FEVi, FEVi/FVC, FEF25-75, FEF75-85) and FVC were even lower and TLC and RV/TLC were higher and all differences were significant (C to A). Comparison of three asbestosis groups (Column C) to age-matched men […]
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Airways Obstruction From Asbestos Exposure: Analysis of Residuals
To provide a second check on the differences between groups, we calculated the residuals. In effect, this comparison age matches each individual and minimizes the effects of differences in age distributions within groups being compared. Thus, we subtracted each man’s measurements from his predicted value to obtain the residuals for FVCi, FEVi, flows, and TLC. […]
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