Abstract
Background: Radiographic surveillance among U.S. coal miners showed declining tenure-specific disease prevalence until 2000, when abnormalities consistent with coal workers' pneumoconiosis (CWP) and progressive massive fibrosis (PMF) began to increase. Some have suggested the increase may be due to selection bias in the surveillance programs.
Methods: For the period 2006-2009, results from the routine health surveillance program (in which costs of radiographs are paid by industry) were compared with results of a government-funded enhanced surveillance program utilizing a mobile examination unit stationed in mining regions. Observed disease prevalence was stratified by region and by mining tenure, and compared between participants in the two programs.
Results: Overall, participants in the routine and enhanced surveillance programs were similar for participation rate, mining location (surface/underground), gender, and race/ethnicity. Participants in the enhanced program were older (47.1 vs 36.4 yr), had longer tenure (21.8 vs 11.4 yr), and higher prevalence of abnormal radiographs (3.9% vs 1.9%) compared to the routine program. However, among miners with at least 20 years of mining, rates of both CWP (6.1% vs 7.0%) and PMF (1.1% vs 0.9%) were similar for participants in the enhanced and routine surveillance programs, respectively.
Conclusions: Tenure-specific prevalences in the routine and enhanced surveillance programs were similar, indicating that selection bias does not explain the recent increases in CWP and PMF among U.S. miners. Previous reports have implicated increased lung deposition of respirable dust and silica as explanations for the ongoing pneumoconiosis problem.
- © 2011 ERS
