Trends in pleural radiographic findings in the Navy Asbestos Medical Surveillance Program (1990-1999)

Our plain-English summary of Trends in pleural radiographic findings in the Navy Asbestos Medical Surveillance Program (1990-1999), by J.G. Muller, B.K. Bohnker, A.F. Philippi, et al (Military Medicine, 2005).

The study

• Authors: J.G. Muller, B.K. Bohnker, A.F. Philippi, F.K. Litow, G. Rudolph, J.E. Hernandez
• Journal: Military Medicine
• Published: 2005;170(5):375-80
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The U.S. Navy Asbestos Medical Surveillance Program is a comprehensive effort to decrease exposure to asbestos, a known health hazard. This study was part of a programmatic review of the Asbestos Medical Surveillance Program database, which included 233,353 radiographic examinations from 1990 to 1999. The initial review focused on incidental findings recorded by B-readers for 23,460 radiographs. Abnormalities reported included bullae (0.68%), cancer (0.56%), cardiac size/ shape abnormalities (1.36%), emphysema (0.74%), subpleural fat (2.62%), fractured ribs (1.24%), hilar adenopathy (0.13%), ill-defined diaphragm (0.46%), ill-defined heart border (0.29%), Kerley lines (0.06%), pleural thickening (2.35%), and tuberculosis (0.27%). The rates by age cohort for pleural abnormalities decreased significantly (30-39 years, chi2 for trend = 23.49, df = 1; 40-49 years, chi2 for trend = 176.21; 50-59 years, chi2 for trend = 401.87), but findings were not significantly different for those > or =60 years of age. This suggests that sequential age cohorts in the program are developing fewer pleural abnormalities; pleural abnormalities have historically been associated with asbestos exposure.

In plain English

The authors reviewed 233,353 chest X-ray readings from 1990 to 1999 in the U.S. Navy Asbestos Medical Surveillance Program database, which covers workers enrolled in the program. Certified B-readers can tick extra "other" findings on the reading form, and 23,460 readings (about 10%) had at least one. The most common were subpleural fat (2.62% of readings) and pleural thickening in the interlobar fissure or mediastinum (2.35%). Comparing 1990–1992, 1993–1995 and 1996–1998, reports of this pleural thickening fell significantly among workers aged 30 to 39, 40 to 49 and 50 to 59, but not among the youngest or oldest. Readings flagged as consistent with cancer, emphysema, bullae or tuberculosis also fell in some age groups. Heart outline abnormalities showed no significant trend. The authors concluded that the decline in pleural findings supports the program's usefulness. They cautioned that these flags are not diagnoses or true disease rates, that smoking was not considered, that repeat X-rays of one person could be counted more than once, and that this pleural marking may be less specific to asbestos than other pleural findings.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective review of a medical surveillance database, with trend analysis (chi-square test for trend) across three time periods: 1990 to 1992, 1993 to 1995 and 1996 to 1998
• Who was studied: 233,353 chest X-ray B-readings from 1990 to 1999 for workers enrolled in the U.S. Navy Asbestos Medical Surveillance Program. The study population was 97% male. Readings were done by experienced CDC/NIOSH-certified B-readers.
• Exposure: Enrollment in the Navy asbestos surveillance program as asbestos workers. Only workers with current exposure are required to enroll, though some commands include workers with only past exposure. Fiber types and exposure levels were not measured or reported.
• Main results:
  • Of 233,353 readings, 23,460 (10.05%) included one or more of the 22 'other' findings.
  • Subpleural fat was reported in 6,120 readings (2.62%). Pleural thickening in the interlobar fissure or mediastinum was reported in 5,487 (2.35%). Findings consistent with cancer of the lung or pleura were reported in 1,301 (0.56%).
  • Reports of pleural thickening decreased significantly over the study period among workers aged 30 to 39, 40 to 49 and 50 to 59.
  • The trend in pleural findings was not statistically significant for the youngest group (under 30) or the oldest group (60 and over).
  • Readings flagged as consistent with cancer decreased significantly among those aged 30 to 39, 40 to 49 and 50 to 59.
  • Emphysema reports decreased significantly among those aged 40 to 49, 50 to 59 and the oldest group. Bullae reports decreased among those aged 40 to 49 and 50 to 59.
  • Tuberculosis reports decreased significantly among those aged 30 to 39, 40 to 49, 50 to 59 and the oldest group.
  • Reports of heart outline (cardiac size or shape) abnormalities showed no significant trend over the period.
• The authors' conclusion: The authors concluded that incidental pleural findings decreased significantly during the study period, noting that pleural abnormalities have been associated with asbestos exposure in the literature, and that the results support the usefulness of the surveillance program.
• Limitations the authors state:
  • X-ray findings were not linked with history and physical examination data, so smoking history and lung function test results were not considered.
  • The pleural finding analyzed ('pi') may be less specifically linked to asbestos than the pleural findings reported in the main section of the form.
  • Less effort by B-readers to report such findings could have influenced reporting rates.
  • Enrollment in the program is not consistent across the Navy.
  • Repeat entries were not excluded, so one person with a stable abnormality could be counted several times.
  • The flagged findings are not confirmed diagnoses, and the reporting rates are not true incidence or disease rates.
  • The findings do not represent true prevalence among Navy personnel. Only enrolled workers are included, and readings used a single X-ray view.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Pleural plaques and thickening, The Navy.

Medical terms in this study, explained in our Lexicon: B-Reader, Emphysema, Diaphragm, Pleural Thickening, Asbestos Exposure.

Related studies

• Navy Asbestos Medical Surveillance Program 1990-1999: demographic features and trends in abnormal radiographic findings — D.M. Dell, B.K. Bohnker, et al. (2006)
• Variability in interpretation among B-readers in the U.S. Navy Asbestos Medical Surveillance Program — J.G. Muller, J.M. Lieske, et al. (2008)
• Navy Asbestos Medical Surveillance Program (1984-1990): linear regression analysis for effect of asbestos exposure on pulmonary function testing — B.K. Bohnker, L.S. Betts, et al. (2004)
• Navy Asbestos Medical Surveillance Program (1991-1999): linear regression analysis for the effect of asbestos exposure on pulmonary function testing — B.K. Bohnker, L.S. Betts, et al. (2004)
• Changes in B-readings over time in the United States Navy Asbestos Medical Surveillance Program — J.G. Muller, W.G. Rudolph, et al. (2007)
• Asbestos-related cancers among 28,300 military servicemen in the Royal Norwegian Navy — L.A. Strand, J.I. Martinsen, et al. (2010)

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