Fig. 5
From: Evidence for harm reduction in COPD smokers who switch to electronic cigarettes
Changes in COPD Assessment Test (CAT) scores from baseline, at follow-up visit 1 (12 ± 1.5 months) and visit 2 (24 ± 2.5 months) separately for electronic cigarettes users (closed circles) and controls (closed triangles). All data expressed as mean and error bars are standard deviation of the mean. The p value is an overall comparison of both groups over the 24-month period