Table 2 .
Analyses of Biomarkers of Exposure and Potential Harm among Dual E-cigarette/Cigarette Users (n = 64)a
| Categories | Baseline mean (SD) | Week 6 mean (SD) | Δ (Week 6–BL) Mean (SD) | p-value (two-sided t-test) |
|---|---|---|---|---|
| NNAL (ng/mL)b | 130.4 (99.2) | 74.6 (71.8) | −55.9 (88.6) | < .001 |
| Cotinine (pg/mL)b | 1160.5 (1042.1) | 1312.5 (1725.9) | 152.0 (1672.8) | .47 |
| Carbon monoxide (CO, ppm) | 16.8 (8.7) | 10.6 (6.4) | −6.3 (8.6) | < .001 |
| BP–systolic (mmHg) | 129.9 (17.2) | 130.4 (18.2) | 0.5 (15.6) | .81 |
| BP–diastolic (mmHg) | 81.9 (9.8) | 81.9 (10.6) | 0.0 (9.3) | .99 |
| FEF25-75c | 3.1 (1.5) | 3.0 (1.6) | −0.1 (1.2) | .49 |
| Respiratory symptomsa,d | 12.7 (8.2) | 9.4 (7.7) | −3.3 (8.0) | .002 |
a Of the 114 participants in the e-cigarette group that completed the week 6 visit (60 in KC, 54 in SD), 64 qualified as dual CC-EC users (35 in KC, 29 in SD) and were categorized separately from e-cigarette only and cigarette only participants at week 6.
b Normalized for creatinine.
c Defined as the average flow from the point at which 25% of the forced vital capacity (FVC) has been exhaled to the point at which 75% of the FVC has been exhaled.
d Respiratory symptoms were asked at the baseline, week 2 and week 6 visits using the American Thoracic Society Questionnaire. Participants responded to 8 statements with 0 (never), 1(less than once per week), 2 (1–2 times per week), 3 (several times per week), or 4 (daily) for a total summed respiratory symptoms scale ranging from 0 to 32.