The prevalence of COPD differed significantly between men and women ( 19 · 0 % , 95 % CI 16 · 9 - 21 · 2 vs 8 · 1 % , 6 · 8 - 9 · 3 ; p < 0 · 0001 ) , mainly because of a significant difference in smoking status between men and women ( current smokers 58 · 2 % vs 4 · 0 % ) .