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Table 1 Prevalence of radiological silicosis by age category and years since first employment in the mining industry, both reading sets

From: Trends in silicosis prevalence and the healthy worker effect among gold miners in South Africa: a prevalence study with follow up of employment status

   Reader I Combined reading
   ILO grade ≥1/0 ILO grade ≥1/1 ILO grade ≥1/0 ILO grade ≥1/1
  N n Prevalence % (95 % CI)a n Prevalence % (95 % CI)a n Prevalence % n Prevalence %
Total 11,557 659   478      
By age (years)
18–44 6468 128 2.0 (1.5, 2.7) 85 1.3 (0.9, 1.8) 56 0.9 98 1.5
45+ 4994 526 10.5 (8.6, 12.9) 389 7.8 (6.1, 10.0) 659 13.2 551 11.0
Totalb 11,462 654 5.7 (4.6, 7.1) 474 4.1 (3.2, 5.3) 715 6.2 649 5.7
By duration since first employment (years)
≤20 5456 81 1.5 (1.1, 2.1) 52 1.0 (0.7, 14.0) 27 0.5 48 0.9
21+ 6020 573 9.5 (7.8, 11.7) 423 7.0 (5.5, 9.0) 681 11.3 618 10.3
Totalc 11,476 654 5.7 (4.6, 7.1) 475 4.1 (3.2, 5.3) 708 6.2 666 5.8
  1. CI confidence interval. All figures rounded to one decimal
  2. a95 % confidence intervals adjusted for clustering using robust standard errors
  3. bRestricted to those with age known (age unknown for n = 95)
  4. cRestricted to those with duration in workforce known (years since first employment unknown for n = 81)