Chest radiographs in subjects with asbestos-related abnormalities: comparison between ILO categorizations and clinical reading.

The findings of a previous chest X-ray screening, determined without using standardized criteria, were reassessed by means of the ILO classification. Of 470 radiographs that had been determined as showing asbestos-related changes, 430 were categorized according to the ILO Classification. Small opacities with profusion greater than or equal to 1/0 were described in 39 (52%) of 75 participants who, on the original clinical reading, had been determined as having lung fibrosis, and in 45 (12.7%) of 355 who were determined as having pleural changes only. When considering circumscribed pleural thickening at the chest wall or diaphragm, as categorized by the ILO Classification, such changes were present in 401 (93.7%) of 428 subjects with pleural changes as determined on the clinical reading. In addition to the improved sensitivity and specificity achieved, the ILO Classification also allows comparison with other studies. The most apparent disadvantage of the ILO system is that it cannot firmly separate the various types of asbestos-related pleural changes. The study revealed that the previous asbestos exposure of the case subjects had occurred in many different workplaces and occupations.     

Asbestos-related pleural diseases: dimensional criteria are not appropriate to differentiate diffuse pleural thickening from pleural plaques

BACKGROUND: In the literature, the criteria used to define pleural plaques (PP) and diffuse pleural thickening (DPT) are very heterogeneous and often imprecise. A multicenter restropective study was conducted to assess the relevance of two radiographic definitions of DPT. METHODS: The study population consisted of 287 subjects with asbestos-related pleural thickening. Two definitions were used to characterize DPT on postero-anterior chest radiographs: definition 1: pleural thickening associated with obliteration of the costophrenic angle; definition 2: pleural thickening at least 5 mm wide, extending for more than one quarter of the chest wall. Prevalence of respiratory symptoms and pulmonary function tests were compared in the DPT and PP groups resulting from the two definitions of DPT. RESULTS: According to definition 1, 34 patients (11.8%) were classified in the DPT group. Prevalence of chronic sputum, dyspnea, and chest pain was significantly higher in this group than in the PP group. FEV(1), FVC, and TLC were significantly lower. The differences persisted after adjustment for confounding factors. According to definition 2,102 patients (36.6%) were classified in the DPT group. DPT and PP groups did not differ in terms of prevalence of respiratory symptoms, or pulmonary function tests. Agreement between readers was significantly better when using definition 1. CONCLUSIONS: Obliteration of costophrenic angle is a much more reliable sign than dimensional criteria to characterize DPT.     

Diffuse malignant pleural mesothelioma in an urban hospital: clinical spectrum and trend in incidence over time

This retrospective analysis reviews the clinical experience of a major urban referral hospital with diffuse malignant pleural mesothelioma during the 14-year period from 1973 through 1986. Seventy-five cases of definite or equivocal mesothelioma were identified. There were four cases of primary malignant peritoneal mesothelioma, seven cases of benign fibrous mesothelioma, and 64 cases of diffuse malignant pleural mesothelioma. In 43 cases (67%) of diffuse malignant pleural mesothelioma, there was historic evidence of asbestos exposure. In 21 cases (33%), there was no known history of asbestos exposure. An increase in annual incidence of diffuse malignant pleural mesothelioma was observed over the study period, from three cases in 1973 to ten cases in 1986. Despite greater awareness of this disease, the diagnosis remains a difficult one to establish given the nonspecific symptoms, signs and radiographic appearance, variable histologic appearance, and poor diagnostic sensitivity and specificity of thoracentesis and closed pleural biopsy. Thoracotomy, thoracoscopy, and CT-guided needle biopsies gave higher yields and are the diagnostic measures of choice when diffuse malignant pleural mesothelioma is suspected.     

Pulmonary abnormalities associated with occupational exposures at the Savannah River Site

BACKGROUND: A program of medical evaluation for former Savannah River Site (SRS) workers at health effects due to exposures to hazardous or radioactive agents was conducted. METHODS: This study includes data from 1,368 participants aged 45 years or older who were assessed regarding work-history and exposures to industrial agents. According to the standard industrial classification (SIC), participants were employed in five of the SIC divisions. Based on the International Labour Office Classification of Radiographs, two categories of pleural and parenchymal abnormalities were evaluated by a single radiologist. The SRS results were compared with the second national health and nutrition examination survey (NHANES II) results. RESULTS: The odds ratio of the SRS male aged 45-75 compared to NHANES was 2.4 for pleura abnormalities and 0.8 for parenchymal abnormalities. Using logistic regression, the highest-risk worker division was construction (OR = 2.76); asbestos exposure was clearly associated with pleural abnormality (OR = 2.15). CONCLUSIONS: Pulmonary abnormalities were higher in former SRS workers than that in general population. Asbestos and possibly other exposures were related to pulmonary disease in this population.     

Radiographic abnormalities in asbestos insulators: effects of duration from onset of exposure and smoking. Relationships of dyspnea with parenchymal and pleural fibrosis

Chest radiographs and spirometry were evaluated in 2,907 active and retired asbestos insulators; most (86.8%) had greater than or equal to 30 years from onset of asbestos exposure. Testing was performed in 19 cities in the United States during 1981-1983. Complete demographic, smoking, clinical, and radiologic data were obtained for 2,790 workers. This is the largest single group of insulators that has been studied. Five hundred forty-eight (19.7%) had never smoked cigarettes, 942 (33.9%) were current cigarette smokers, and 1,300 (46.6%) were ex-smokers. Only 439 (15.7%) workers had no radiographic evidence of asbestos-related disease (normal chest X-ray); 668 (23.9%) had pleural fibrosis only, 325 (11.6%) had parenchymal fibrosis alone, and 1,358 (48.7%) had both parenchymal and pleural fibrosis. The prevalence of radiographic parenchymal changes increased significantly (p less than .001) from 38.6% (DURONSET less than 30 years) to 70% (greater than or equal to 40 years). For pleural changes the comparative prevalences were 55% and 82%. Those with no history of cigarette smoking were more likely to have normal films than those with a history of smoking (19.2% versus 14.4% for current smokers and 15.2% among ex-smokers), and were less likely to have parenchymal fibrosis (44.5% versus 69.7% for current smokers and 60.2% of ex-smokers). Dyspnea, MRC grade 3 and higher, was more prevalent when pleural fibrosis was associated with interstitial pulmonary fibrosis (at all profusion levels of small opacities) than when pleural fibrosis was absent. Logistic regression analysis of factors contributing to such dyspnea showed that the presence of combined parenchymal and pleural abnormalities was a significant explanatory variable, in addition to age, smoking, and body mass (Quetelet index); the presence of parenchymal changes only or of pleural changes only, as factors contributing to dyspnea, did not reach the level of statistical significance in the regression analysis. The results of these examinations show that pleural fibrosis is a frequent finding in asbestos-exposed groups with long-term follow-up and that its functional significance is not negligible. The contribution of cigarette smoking to prevalence and severity of interstitial fibrosis is an additional reason for smoking cessation among asbestos-exposed individuals.     

Fissural thickening and exposure to asbestos: occurrence, determinants, and functional impact.

The occurrence and determinants of thickened interlobar fissures were assessed in 147 insulators, in order to test the hypothesis that radiographic abnormalities in minor (FMN) and/or major (FMJ) interlobar fissures are associated with restrictive respiratory impairment, which may reflect early parenchymal lung fibrosis. According to the diagnostic criteria developed, definite interlobar thickening was found in 33 (FMN) and in 73 (FMJ) men, and was frequently associated with the presence of classical asbestos pleural disease, though not parenchymal abnormality. Multivariate analyses did not demonstrate any association between either FMN or FMJ and lung function. Such an association, however, was found in the case of the usual asbestos-related pleural change. These findings suggest that fissural thickening seen on chest radiography represents a component of asbestos pleural disease and not asbestosis.     

Pulmonary function,smoking habits,and high resolution computed tomography (HRCT) early abnormalities of lung and pleural fibrosis in shipyard workers exposed to asbestos

To evaluate the presence of asbestos-related pleural and parenchymal abnormalities and their correlation with pulmonary function and smoking habits, 119 asbestos-exposed asymptomatic workers (mean age, 46.2 years; mean duration of asbestos exposure, 8.6 years; mean latency time, 21.6 years) with normal standard P-A chest radiographs were submitted to HRCT, CO-diffusing capacity, and pulmonary function tests. HRCT scans were normal only in 31 (26%) examined workers; 31 (26%) subjects showed both pleural and parenchymal involvement, and 50 (42%) and seven (6%) had exclusively pleural and parenchymal abnormalities, respectively. Based on CO-diffusing capacity and pulmonary function tests, no significant difference was demonstrated between workers with pleural lesions and subjects with normal pleura; however, lower values of FVC were observed in the nonsmoking workers with parenchymal abnormalities in comparison with nonsmoking subjects with normal parenchyma (78.2 vs. 89.7% of predicted values; p = 0.03 by student's two-tailedttest), and lower values of FEV₁/FVC in the smokers with parenchymal lesions with respect to smokers with normal parenchyma (93.7 vs. 100.2% of predicted values; p = 0.005 by student's two-tailedttest). In conclusion, our results demonstrate that HRCT may detect early parenchymal abnormalities which correlate with exposure to asbestos and respiratory function impairment, including a reduction in obstructive indices in smokers occupationally exposed to asbestos, without any clinically evident disease. © 1996 Wiley-Liss, Inc.     

Use of an Asbestos Exposure Score and the Presence of Pleural and Parenchymal Abnormalities in a Lung Cancer Case Series

Abstract

To assess whether there was an association between asbestos exposure and abnormalities on chest x-rays or CT scans, chest radiographs and CT scans of 103 asbestos-exposed patients with known lung cancer were reviewed for pleural or parenchymal abnormalities. Asbestos exposure was assessed using an asbestos exposure index that integrated time and intensity of reported exposure via a weighting scheme. Chest CT scans were clearly more sensitive in detecting pleural or parenchymal abnormalities than were standard PA chest x-rays. Furthermore, there was a significant correlation between higher asbestos exposure index scores and abnormalities on CT scans. Multivariable logistic regression models were used to investigate the relationship between the asbestos exposure index score and pleural or parenchymal abnormalities after adjusting for gender, pack-years of smoking, and cell type. None of these variables was associated with abnormalities on chest x-rays or CT scans. An asbestos exposure score > 10 was associated with pleural or parenchymal abnormalities (OR = 4.93; 95% CI 1.05–23.12). The results suggest that assessment of asbestos exposures by means of an algorithm-based index can classify the exposures accurately for epidemiologic studies.     

Observer variation in classifying chest radiographs for small lung opacities and pleural abnormalities in a population sample

Background The purpose of this study was to assess inter- and intraobserver variation in the radiographic categories of small lung opacities (profusion) and pleural abnormalities classified according to the ILO classification of pneumoconioses with some modifications. Methods Chest radiographs derived from a representative adult population sample (n = 7,095) were classified by two radiologists. Observer variation was assessed on the basis of kappa (κ)-type statistics. Results The observers agreed on profusion categories in 69% of cases of the total material. Up to 98% of the classifications fell into the same category or deviated by no more than one category. The corresponding kappa (κ) coefficient was 0.48 (95%CI = 0.46–0.49) and the weighted κ 0.72. When a selected subsample was reclassified by the observers, the proportions of crude agreement on profusion of small opacities ranged from 42% to 47% (weighted κ 0.52–0.55). The proportions of agreement on the main pleural abnormalities were 92% or over, and the corresponding κ coefficients at least 0.73. Conclusion The classification of lung opacities was subject to considerable observer variation, which calls for caution when results from different studies are compared. This variation, however, rarely exceeded one category, and thus appears to be small enough for meaningful comparisons between groups, at least within a single study. Am. J. Ind. Med. 34:261–265, 1998. © 1998 Wiley-Liss, Inc.     

Relationship of mortality, occupation, and pulmonary diffusing capacity to pleural thickening in the First National Health and Nutrition Examination Survey

We studied the relationship of pleural thickening consistent with asbestos exposure to mortality, career employment in asbestos-related jobs, and pulmonary diffusing capacity among participants in the first National Health and Nutrition Examination Survey. Three "B" readers examined chest X-rays to identify 59 individuals with such pleural abnormalities. From 1975 to 1984, the all-cause mortality rate ratio (RR) comparing males with and without occupational pleural thickening was 1.3 (95% C.I. 0.8-2.2). For lung cancer, the mortality RR for males was 3.0 (95% C.I. 1.0-9.1). Career asbestos work was not associated with occupational pleural thickening among men, probably because some with the condition had only short-term exposure to asbestos. Pulmonary diffusing capacity was lower in those with occupational pleural thickening, taking smoking into account. These results suggest that individuals in the general population who have occupational pleural thickening are at risk for some of the health consequences of asbestos work, including lung cancer, even if they were not career asbestos workers.     

Inflammation of the visceral pleura, a nonspecific asbestos-related pleural reaction: chest radiograph and computed tomograph correlation

Nonspecific pleuritis, i.e., inflammation of the visceral pleura, is recognized by the presence of pleural strands on the routine posteroanterior chest radiograph. The computed tomograph counterparts of these strands are seen as interlobular septal intrusions and lenticular or wedge-shaped subpleural opacities. The pleural reaction is nonspecific and may be found with asbestos exposure, traumatic hemorrhagic effusions, pulmonary embolism, viral pleurisy, malignant pleural effusions, and lupus or rheumatoid effusions. The asbestos-related pleural changes may be found alone or in association with parietal pleural plaque formation or with asbestotic lung fibrosis.     

Lung function and respiratory symptoms in subjects with asbestos-related disorders: a cross-sectional study

The prevalence of respiratory symptoms and lung function impairment was studied in a sample of men from a population screening of asbestos-related disorders. When the rates were adjusted for age and smoking habits, 83 subjects with lung fibrosis had an increased prevalence of respiratory symptoms, in particular, phlegm when coughing and breathlessness grades 1-3. Among 200 subjects under 70 years of age who had pleural plaques only, a statistically significant increase was observed in the prevalence of breathlessness grade 1 compared to an external reference population. Among 98 asbestos-exposed subjects who had normal chest X-rays, there was an increase in the prevalence of breathlessness grade 2, cough during the day, and phlegm when coughing. There was a higher proportion of subjects with lung fibrosis who were below 80% of the predicted values for forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) than in the other groups. There was also a higher proportion of subjects with pleural plaques only who were below 90% of the predicted value for FVC than in a group of 90 subjects without asbestos exposure. In accordance with previous studies, these results indicate that pleural plaques in asbestos workers may be of greater importance as a clinical feature than has been recognized in the past.     

Asbestos-related pleural disease due to tremolite associated with progressive loss of lung function: serial observations in 123 miners, family members, and residents of Libby, Montana

BACKGROUND: The community of Libby, Montana has recently been the focus of national attention secondary to widespread amphibole contamination associated with vermiculite mining and processing. METHODS: Patients who had occupational and non-occupational exposure to amphibole asbestos in Libby, Montana were evaluated for progressive loss of pulmonary function. RESULTS: Of the 123 patients evaluated, 94 demonstrated average age-corrected accelerated loss per year of vital capacity at 3.2%, total lung capacity (TLC) 2.3%, and DLCO 3.3%. All patients all had predominantly pleural changes with minimal to no interstitial disease. CONCLUSIONS: The study demonstrates a progressive loss of pulmonary function in patients exposed to tremolite asbestos.     

Lower limit of normal based spirometric abnormalities associated with radiographic abnormality in an elderly cohort at low risk for exposure

Background: Although the relation between radiographic abnormalities and spirometric impairment in people with asbestosis has been studied extensively, the extent of spirometric impairment associated with milder radiographic abnormalities is not established.

Objective: To test associations between mild radiographic abnormalities and Lower Limit of Normal (LLN)-based spirometry interpretation.

Methods: Spirometry and CXRs were collected for 1,026 at low risk of exposure to pneumoconiotic agents participants in a medical screening program.

Results: Individuals with each type of isolated or combined International Labour Organization (ILO) abnormalities had up to over sixfold statistically significant increase in odds of LLN-based restrictive pattern physiology (OR = 1.96, 95%CI 1.03–3.73 for parenchymal to OR = 6.09, 95%CI 1.94–19.10 for parenchymal and pleural) compared to those with normal films.

Conclusions: The findings from this study confirm the association of mild profusion abnormalities with clinically relevant, LLN-based lung function abnormalities.     

Reducing attenuation in exposure-response relationships by exposure modeling and grouping: the relationship between wood dust exposure and lung function

BACKGROUND: In a study of wood dust exposure and lung function, we tested the effect on the exposure-response relationship of six different exposure metrics using the mean measured exposure of each subject versus the mean exposure based on various methods of grouping subjects, including job-based groups and groups based on an empirical model of the determinants of exposure. METHODS: Multiple linear regression was used to examine the association between wood dust concentration and forced expiratory volume in 1s (FEV(1)), adjusting for age, sex, height, race, pediatric asthma, and smoking. RESULTS: Stronger point estimates of the exposure-response relationships were observed when exposures were based on increasing levels of aggregation, allowing the relationships to be found statistically significant in four of the six metrics. The strongest point estimates were found when exposures were based on the determinants of exposure model. CONCLUSIONS: Determinants of exposure modeling offers the potential for improvement in risk estimation equivalent to or beyond that from job-based exposure grouping.     

Alveolar fiber load in asbestos workers and in subjects with no occupational asbestos exposure: an electron microscopy study

The alveolar fiber load was evaluated by bronchoalveolar lavage and by scanning and transmission electron microscopy (SEM and TEM) in 50 subjects with or without occupational exposure to asbestos. The concentration of asbestos fibers in bronchoalveolar lavage was significantly higher in the groups of people currently and formerly occupationally exposed, compared to the concentration found in people only exposed environmentally, despite wide interindividual variation within the groups. Nonasbestos inorganic fibers were present in all groups, but the concentrations did not differ significantly. Both in people occupationally exposed and in those only environmentally exposed, the alveolar load consisted mainly of ultrashort and ultrathin fibers, which can be studied only with TEM. In fact, the percentage of fibers greater than 5 micron long was only around 15% in the occupationally exposed and was minimal in those only environmentally exposed. The geometric mean diameters of asbestos fibers retained in the alveoli ranged from 0.05 micron for chrysotile to 0.15 micron for amphiboles.