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Table 2 Comparison of prevalence of silicosis by age: 1984 study [7, 8] versus current study (ILO grade ≥1/0)

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

1984 study Current study
Age (years) N (%) Cases n Silicosis prevalence % (95 % CI)a Age (years) N Age distribution % Silicosis prevalence (reader I) % (95 % CI)b Silicosis prevalence (combined reading) (%)
≤45 125,038 (94.2) 1009 0.8 (0.8, 0.9) ≤44 6468 56.4 2.0 (1.5, 2.7) 0.9
46+ 7726 (5.8) 801 10.4 (9.7, 11.1) 45+ 4994 43.6 10.5 (8.6, 12.9) 13.2
Crude 132,765 1810 1.4 (1.3, 1.4) Crude 11,462 100 5.7 (4.6, 7.1) 6.2
Adjustedc    5.0      
  1. All figures rounded to one decimal
  2. a95 % confidence intervals using binomial exact standard errors
  3. b95 % confidence intervals adjusted for clustering using robust standard errors
  4. cAge standardised to current study age distribution