Systematic review of pleural plaques and lung function.

Area of Science:

• Environmental Health
• Occupational Medicine
• Pulmonary Medicine

Background:

• US EPA proposed a Reference Concentration for Libby amphibole asbestos, assuming pleural plaques indicate adverse health effects and lung function deficits.
• This premise requires evaluation to determine the actual health implications of pleural plaques.

Purpose of the Study:

• To systematically review and evaluate the association between pleural plaques and lung function.
• To determine if study methodology (HRCT vs. X-ray) influences observed associations.

Main Methods:

• Systematic literature search of the PubMed database for studies on pleural plaques and lung function.
• Quality assessment of identified studies using risk-of-bias analysis.
• Evidence integration and association assessment based on Bradford Hill guidelines.
• Comparison of results from High-Resolution Computed Tomography (HRCT) and X-ray studies.

Main Results:

• 16 HRCT and 36 X-ray studies were identified; 6 HRCT and 16 X-ray studies were rated as higher quality.
• Half of higher quality studies reported statistically significant, but not clinically significant, lung function decrements.
• Limitations included inappropriate controls and insufficient confounder adjustment; results lacked consistency.
• Longitudinal studies showed no association between pleural plaques and lung function changes over time.

Conclusions:

• The weight of evidence suggests pleural plaques do not impact lung function.
• Observed associations in some studies are likely attributable to unidentified abnormalities or confounding factors.