When each multivariate model was adjusted for the number of daily cigarettes smoked currently instead of pack-years, the significance of FTND was persistent in only control subjects for severity of emphysema (β = -0.06, p = 0.008 for controls; β = -0.02, p = 0.57 for COPD) and the effect of FTND on gas trapping failed to reach statistical significance (β = 0.38, p = 0.12 for controls; β = -0.08, p = 0.86 for COPD).
1
0.1200
0.1200