Chest
Opinions/HypothesesThe Clinical Diagnosis of Asbestosis in This Century Requires More Than a Chest Radiograph
Section snippets
Mortality Risk From Lung Cancer in Various Asbestos-Exposed Cohorts
Occupational exposure to asbestos is a well-recognized risk factor for primary cancer of the lung. However, the size of the risk varies quite markedly depending on the cohort and the date of the study (earlier studies generally reflect the effects of much heavier exposure). For example, in a study of insulators published in 1979, lung cancer mortality was increased more than four times compared to control subjects,3 whereas in a study4 of shipyard workers in Hawaii, the incidence of lung cancer
Risk of Lung Cancer Associated With Asbestosis
Pathologic asbestosis is associated with a significant increase in lung cancer risk. In one study, an approximate fivefold increase in lung cancer was found among an insulator cohort.25 Later, autopsy studies26 on this group of lung cancer patients found that virtually all had asbestosis. Hughes and Weill27 found that in a cohort of workers producing asbestos-containing cement and pipe covering those with radiographic evidence of asbestosis had a lung cancer risk that was more than four times
Prevalence of Asbestosis
The prevalence of pathologic asbestosis has not been accurately determined for asbestos-exposed workers. This would require the examination of lung tissue from a large number of randomly selected people, which is not feasible. Furthermore, the definition of asbestosis has to be determined. Is it solely based on pathology or does there have to be some physiologic dysfunction? Furthermore, what is the minimal amount of pathologic abnormality that is associated with an increased risk of lung
Sensitivity and Specificity of the Chest Radiograph in the Diagnosis of Asbestosis
The chest radiograph has long been used as an important tool in the diagnosis of diffuse interstitial pulmonary fibrotic diseases such as asbestosis. Extensive disease can usually be accurately detected by a well-trained radiologist or physician. Of course, it is necessary to exclude diseases that radiologically can be confused with diffuse interstitial pulmonary fibrosis, such as congestive heart failure or lymphangitic spread of malignancy. Also, the differential diagnosis of interstitial
Positive Predictive Value of the Chest Radiograph Alone
From these previous discussions, reasonable estimates of asbestosis prevalence among present-day construction or petrochemical workers, as well as the sensitivity and specificity of the chest radiograph in diagnosing asbestosis, can be made. From this, the positive predictive value of the chest radiograph can be obtained. The prevalence of asbestosis in this at-risk population could be expected to be about 1 to 5%. In addition, from the previous discussion, at least 5 to 10% of the time the
Other Imaging Techniques
High-resolution CT (HRCT) scans of the chest are better than chest radiographs for the evaluation of asbestosis. They are more sensitive and more specific. However HRCT scans also can miss pathologic asbestosis. Furthermore, minimal changes on HRCT scans are nonspecific and often do not indicate fibrosis.52,53 Even if the sensitivity and specificity increased to 95%, the positive predictive value of the HRCT scan alone would be only 50% if the prevalence of asbestosis were 5%, and 37% if the
Usefulness of the History, Physical Examination, and Other Physiologic Tests in Diagnosing Asbestosis
In its position statement regarding nonmalignant disease related to asbestos,1 the American Thoracic Society also mentioned that it is important to obtain a good occupational history and that rales, restriction, and a diffusing capacity of the lung for carbon monoxide (Dlco) below the limit of normal are of recognized value in diagnosing asbestosis. These will now be discussed.
The Clinical Diagnosis of Asbestosis
How can these various clinical diagnostic findings be used in order to diagnose asbestosis within a reasonable degree of certainty without too many false-positive diagnoses or too many false-negative diagnoses when lung tissue is not available? The chest radiograph is positive in approximately 90% of cases. Furthermore, pleural plaques are often present in patients with asbestosis.65 Rales occur in approximately 70 to 90% of cases, and a reduced Dlco occurs in about 80 to 90% of cases.
Summary
Among persons in present-day asbestos-exposed cohorts, such as construction and petrochemical workers, an abnormal chest radiograph (ILO grade, 1/0 and 1/1) alone may have a positive predictive value that is too low to diagnose asbestosis with confidence. However, the diagnosis of asbestosis usually can be made on clinical grounds. Many patients will have pleural plaques. Most patients will have radiographic changes that are suggestive of diffuse interstitial pulmonary fibrosis, reduced Dlco,
References (65)
- et al.
The quantitative risks of mesothelioma and lung cancer in relation to asbestos exposure
Ann Occup Hyg
(2000) Asbestosis: a marker for the increased risk of lung cancer among workers exposed to asbestos
Chest
(1999)- et al.
The significance of irregular opacities on the chest roentgenogram
Chest
(1992) - et al.
Variability in the classification of radiographs using the 1980 International Labor Organization classification for Pneumoconioses
Chest
(1998) - et al.
Prevalence of small lung opacities in populations unexposed to dusts: a literature analysis
Chest
(1997) - et al.
Crackles in asbestos workers: auscultation and lung sound analysis
Br J Dis Chest
(1981) - et al.
Observer agreement, chest auscultation, and crackles in asbestos-exposed workers
Chest
(1986) - et al.
The sensitivity of high-resolution CT in detecting idiopathic pulmonary fibrosis proved by open lung biopsy: a prospective study
Chest
(1995) Medical Section of the American Lung Association: the diagnosis of nonmalignant diseases related to asbestos
Am Rev Respir Dis
(1986)Guidelines for the use of ILO international classification of radiographs of pneumoconioses. Occupational safety and health series No.22
(1980)
Mortality experience of insulation workers in the United States and Canada, 1943–1976
Ann N Y Acad Sci
Cancer occurrence in shipyard workers exposed to asbestos in Hawaii
Cancer Res
Cancer in asbestos-exposed occupational cohorts: a meta-analysis
Cancer Causes Control
Cancer mortality among petroleum refinery and chemical manufacturing workers in Texas
J Environ Pathol Toxicol Oncol
Lung cancer among steelworkers in Ontario
Am J Ind Med
Occupational exposure to asbestos: population at risk and projected mortality: 1980–2030
Am J Ind Med
Assessment of mortality in the construction industry in the United States, 1984–1986
Am J Ind Med
Proportionate mortality among construction laborers
Am J Ind Med
Mortality of Carpenters’ Union members employed in the US construction or wood products industries, 1987–1990
Am J Ind Med
A 50-year mortality follow-up of a large cohort of oil refinery workers in Texas
J Occup Environ Med
Mortality among maintenance employees potentially exposed to asbestos in a refinery and petrochemical plant
Am J Ind Med
Cohort mortality study of pulp and paper mill workers in British Columbia, Canada
Am J Epidemiol
Proportionate mortality among unionized construction operating engineers
Am J Ind Med
Proportionate mortality among unionized construction ironworkers
Am J Ind Med
An updated mortality study of workers at a petroleum refinery in Beaumont, Texas
Am J Ind Med
Proportionate mortality among union members employed at three Texas refineries
Am J Ind Med
Mortality among North Carolina construction workers, 1988–1994
Appl Occup Environ Hyg
Mortality patterns among electrical workers employed in the US construction industry, 1982–1987
Am J Ind Med
Cohort mortality study of 57,000 painters and other union members: a 15 year update
Occup Environ Med
Updated mortality among diverse operating segments of a petroleum company
Occup Environ Med
Proportionate mortality among unionized roofers and waterproofers
Am J Ind Med
Mortality among unionized construction plasterers and cement masons
Am J Ind Med
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2011, Disease-a-MonthCitation Excerpt :This would support the contention that asbestosis is not necessary to attribute lung cancer to asbestos exposure. However, even our most sensitive radiologic and clinical methods may not be enough to detect histologically present fibrosis.30 Indeed, the definition of asbestosis has varied study to study, from histologic evidence, to computed tomography (CT), to plain film chest x-ray.
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