Chest
Volume 125, Issue 2, February 2004, Pages 744-753
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Occupational and Environmental Lung Disease
Changing Patterns in Asbestos-Induced Lung Disease

https://doi.org/10.1378/chest.125.2.744Get rights and content

Study objectives

To determine patterns in asbestos-induced lung diseases found in older, less exposed workers.

Design

Review of a database evaluating lung function, smoking status, form of asbestos-induced lung disease, and radiograph abnormalities.

Setting

Outpatient clinic.

Participants

A total of 3383 asbestos-exposed workers referred for independent medical evaluation, including control subjects who lacked asbestos-specific radiograph abnormalities (n = 243), subjects with low International Labor Organization (ILO) scores (n = 2,685), high ILO scores (n = 312), bronchogenic cancer (n = 63), and mesothelioma (n = 80). Of these, 3,327 workers have specific smoking status information and 3,312 workers have lung volume measures.

Interventions

Chest radiographs were interpreted by a certified B-reader, and abnormalities were quantified according to the ILO scoring system. Spirometry and lung volume measurement were performed. Subjects completed a self-administered questionnaire that was reviewed at the time of examination. Control subjects were screened on two separate occasions at least 10 years apart to exclude subclinical or slowly progressive asbestos-induced lung disease.

Measurements and results

The mean age of the population was 65.1 ± 9.9 years, and the latency was 41.4 ± 10.1 years (± SD). Most subjects (41.8%) had normal pulmonary function. Obstruction was the most common pulmonary function abnormality (25.4%), followed by restriction (19.3%) and a mixed pattern (6.0%). Most subjects (79.4%) had low ILO scores. Benign pleural abnormalities were the only findings in 54% of subjects with low ILO score. Subjects with high ILO scores were older, smoked more, and had a longer latency than subjects with low ILO scores and control subjects. Smokers were younger, had a shorter latency, and had paradoxically greater ILO scores than nonsmokers. Subjects with bronchogenic cancer and mesothelioma had longer latencies than control subjects and subjects with benign asbestos-induced lung disease.

Conclusions

Asbestos-induced lung disease today is characterized by low ILO scores, long latencies, greater disease magnitude in smokers, and a normal or obstructive pattern of pulmonary function abnormality. Spirometric evaluation in the absence of lung volume measurements caused misclassification that resulted in overestimation of the presence of a restrictive pattern of pulmonary function.

Section snippets

Materials and Methods

To test this hypothesis, we assessed patterns of asbestos-induced lung disease from a registry of asbestos-exposed workers (n = 3,383) established as the Selikoff registry. All patients were referred for independent medical evaluation. Entry criteria for an independent medical evaluation included documented workplace asbestos exposure, an elapsed time from date of first exposure (latency) of > 10 years, and an abnormal chest radiograph pattern consistent with the history of asbestos exposure.

Demographics

The mean age (± SD) of the study population was 65.1 ± 9.9 years (range, 28 to 93 years) [white race, 93%; male gender, 96%]. Six percent of the individuals were African Americans, and 1% characterized themselves as “other” race. Nearly two thirds of the workers could be classified with six job descriptors (Fig 1). A small number of subjects had a diagnosis of lung cancer (1.9%) or mesothelioma (2.4%). These individuals tended to be older than control subjects and subjects with nonmalignant

Discussion

In this study, we found that most subjects had normal pulmonary function. When pulmonary function abnormalities were present, the dominant finding was airways obstruction. Spirometric evaluation in the absence of lung volume measurements caused misclassification of subjects who had obstruction with coexistent airtrapping as part of the mixed-pattern group. This misclassification resulted in overestimation of the presence of a restrictive pattern of pulmonary function by attributing causation of

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    Dr. Ohar has served as an expert witness for both the defense and plaintiffs in judicial pleadings for compensation for asbestos-induced diseases.

    Financial support was provided by the Selikoff Fund, Saint Louis University.

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