Table 3

Prevalence ratios and 95% CIs of r-type opacities among participants in the NIOSH Coal Workers' X-Ray Surveillance program, 1980–2008, any tenure

Prevalence ratios and 95% CI
1990s vs 1980s2000+ vs 1990s2000+ vs 1980s
USA except Kentucky, Virginia, West Virginia1.0 (0.49 to 1.8)1.6 (0.86 to 3.0)1.5 (1.0 to 2.4)
Kentucky, Virginia, West Virginia2.5 (1.7 to 3.7)1.6 (1.2 to 2.2)4.1 (3.0 to 5.6)
All USA1.9 (1.3 to 2.7)1.7 (1.2 to 2.3)3.1 (2.4 to 4.1)
  • Log binomial regression was used for miner age and small opacity profusion adjustments. Prevalence ratios were calculated separately for each region. Models were of the form: r-type opacity=α+β1(1990s)2(2000+)3(Profusion category 0)4(Profusion category 1)5(Profusion category 2)5(Age).