Table 2.

Regression Analysis of Outcomes for FMD—Linear Contrast With Higher Arm Less Nicotine

	Difference Between Arms in Change	p Value
Primary outcome*
Change in FMD (+1 group, 1 = TC, 2 = EC-nicotine, 3 = EC-nicotine-free)	0.73 (0.41 to 1.05)	<0.0001
Secondary outcomes*
Change in FMD, EC-nicotine-free vs. TC (ref)	1.52 (0.90 to 2.15)	<0.0001
Change in FMD, EC-nicotine vs. TC (ref)	1.44 (0.78 to 2.09)	<0.0001
Change in FMD, all EC vs. TC (ref)	1.49 (0.93 to 2.04)	<0.0001
Change in FMD, EC-nicotine-free vs. EC-nicotine (ref)	0.09 (−0.52 to 0.69)	0.78

Values are regression coefficient (95% CI).

CI = confidence interval; FMD = flow-mediated dilatation; ref = reference; other abbreviations as in Table 1.

^∗Adjusted for baseline of the outcome, baseline age (≤40 years, >40 years), sex (male, female), and smoking pack-years (≤20 pack-years, >20 pack-years).