Pleural abnormalities in the Framingham Heart Study: prevalence and CT image features

Abstract

Background The prevalence of pleural abnormalities in the general population is an epidemiologically important index of asbestos exposure, which has not been investigated since a radiography-based study in 1980. Methods We examined 2633 chest CT scans (mean 59.2 years, 50% female) from the Framingham Heart Study (FHS) for the presence and image characteristics of pleural plaques and diffuse pleural thickening. Demographics and pulmonary function were stratified by the presence of pleural abnormalities in association with interstitial lung abnormalities (ILA). Results Pleural abnormalities were present in 1.5% (95% CI: 1.1–2.1%). Pleural lesions were most commonly bilateral (90.0%), multiple (77.5%), calcified (97.5%), and commonly involved posterior (lower: 92.5%, middle: 87.5%), anterior (upper: 77.5%, middle: 77.5%), and diaphragmatic areas (72.5%). Participants with pleural abnormalities were significantly older (75.7 years, p<0.0001), male (92.5%, p<0.0001), former or current smokers (80.0%, p<0.001) with higher pack-years (33.3, p<0.0001). No significant reduction was noted in pulmonary function measures (p=0.07–0.94) when adjusted for the associated covariates, likely due to small number of cases with pleural abnormalities. Information about prior history of asbestos exposure and occupation was not available. Conclusions Pleural plaques and diffuse pleural thickening are present on CT in 1.5% of the FHS cohort. The current prevalence of the pleural abnormalities is smaller than that reported in the previous population-based study using chest radiography, likely representing lower asbestos exposure in recent decades. The posterior portion of the pleura is most frequently involved but the anterior portion is also commonly involved.

Change in prevalence of asbestos‐related disease among sheet metal workers 1986 to 2016

“…OSHA's earliest limits were set “primarily to protect employees against asbestosis.” Its 1986 determination concluded that reducing the PEL to 0.2 f/cc would reduce the asbestos cancer mortality risk from lifetime exposure to 7 deaths per 1000 workers, and the incidence of asbestosis to 5 cases per 1000 workers . Although the prevalence of chest radiographic findings among the post‐1973 cohort is low compared with the earlier cohorts, it is also higher than what is found in the general population, leading us to conclude that asbestos‐related disease has not yet been eliminated in exposed populations in the United States.…”

Potential asbestos exposure among patients with primary lung cancer in Japan

“…Since the prevalence of pleural plaques varies widely between studies, our findings must be considered alongside evidence from other epidemiological studies. In one such study, the reported prevalence of pleural abnormalities, pleural plaques and diffuse pleural thickening was 1.5% among 2633 chest CTs taken between 2009 and 2011 in the United States 19) . That study considered a general population of white, middle-class Americans, compared to our study of Japanese lung cancer patients, and included a younger age group (59.2±12.1 years compared to 71.3±9.9 years) and a higher proportion of females (50.3% compared to 27.6%).…”

Author reply: ‘Response to: Pleural abnormalities in the Framingham Heart Study: prevalence and CT image features’ by Araki et al

“…We appreciate the comments by Franzblau et al 1 on our recent article ‘Pleural abnormalities in the Framingham Heart Study: prevalence and CT image features’ 2. Our study described CT image findings of pleural abnormalities including pleural plaques and pleural thickening in the Framingham Heart Study.…”