Table 2. Trends by Biomarker of Exposure for Smokers, Nonnicotine Vapers (NNVs), and Nicotine Vapers (NVs), 2013-2019a.
| Wave 1 (Sep 2013 to Dec 2014) | Wave 2 (Oct 2014 to Oct 2015) | Wave 3 (Oct 2015 to Oct 2016) | Wave 4 (Oct 2016 to Jan 2018) | Wave 5 (Dec 2018 to Nov 2019) | P value for within-group linear trendb | |
|---|---|---|---|---|---|---|
| Total nicotine equivalents, mean (95% CI), nmol/mg of creatinine c | ||||||
| Smokers | 27.3 (24.1-30.9) | 29.6 (27.0-32.5) | 32.8 (29.4-36.7) | 29.5 (26.2-33.2) | 30.8 (26.5-35.7) | .34 |
| NNVs | 0.8 (0.2-3.1) | 0.2 (0-0.8) | 0.2 (0.1-0.6) | 0.2 (0.1-0.5) | 0.2 (0.1-0.6) | .29 |
| NVs | 11.0 (7.2-16.7) | 14.3 (9.5-21.7) | 18.9 (13.9-25.7) | 19.4 (14.4-26.2) | 21.8 (15.2-31.4) | .001 |
| Smokers vs NNVsd | 33.7 (9.0-126.5) | 168.9 (39.4-723.6) | 165.7 (52.4-524.2) | 173.0 (56.6-528.5) | 149.9 (47.4-474.0) | |
| P valuee | <.001 | <.001 | <.001 | <.001 | <.001 | |
| NVs vs NNVsd | 13.5 (3.7-50.0) | 81.9 (17.9-374.7) | 95.2 (29.3-309.9) | 113.9 (36.9-351.4) | 106.3 (33.5-337.3) | |
| P valuee | <.001 | <.001 | <.001 | <.001 | <.001 | |
| Smokers vs NVsd | 2.5 (1.6-3.8) | 2.1 (1.4-3.1) | 1.7 (1.3-2.4) | 1.5 (1.1-2.1) | 1.4 (0.9-2.1) | |
| P valuee | <.001 | .004 | .007 | .07 | .32 | |
| Cotinine, mean (95% CI), ng/mg of creatinine f | ||||||
| Smokers | 1750.1 (1551.6-1974.0) | 1888.6 (1729.7-2062.1) | 2109.3 (1882.3-2363.6) | 1868.0 (1659.7-2102.4) | 2002.0 (1724.8-2323.8) | .17 |
| NNVs | 49.9 (12.3-203.2) | 9.9 (2.3-42.5) | 11.2 (3.6-34.5) | 11.1 (3.5-34.6) | 12.2 (4.2-35.8) | .35 |
| NVs | 709.0 (454.0-1107.3) | 965.4 (627.7-1484.6) | 1186.8 (865.3-1627.8) | 1226.1 (890.7-1687.9) | 1416.6 (993.7-2019.4) | .002 |
| Smokers vs NNVsd | 35.1 (8.8-139.9) | 191.4 (44.8-818.1) | 188.4 (60.7-585.2) | 168.5 (53.5-529.7) | 164.3 (55.0-490.6) | |
| P valuee | <.001 | <.001 | <.001 | <.001 | <.001 | |
| NVs vs NNVsd | 14.2 (3.5-57.1) | 97.8 (21.4-446.3) | 106.0 (33.2-338.6) | 110.6 (34.8-351.5) | 116.2 (38.7-349.3) | |
| P valuee | .001 | <.001 | <.001 | <.001 | <.001 | |
| Smokers vs NVsd | 2.5 (1.6-3.9) | 2.0 (1.3-3.0) | 1.8 (1.3-2.5) | 1.5 (1.1-2.1) | 1.4 (1.0-2.1) | |
| P valuee | <.001 | .008 | .003 | .06 | .22 | |
| Tobacco-specific nitrosamine: 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), mean (95% CI), pg/mg of creatinine g | ||||||
| Smokers | 197.4 (180.2-216.2) | 204.2 (188.2-221.5) | 235.4 (216.1-256.3) | 218.3 (197.4-241.3) | .07 | |
| NNVs | 10.1 (4.9-20.9) | 3.3 (1.3-8.5) | 3.9 (2.4-6.3) | 3.8 (1.9-7.5) | .16 | |
| NVs | 6.3 (4.9-8.3) | 5.9 (4.6-7.7) | 4.9 (4.0-5.9) | 5.1 (3.9-6.6) | .14 | |
| Smokers vs NNVsd | 19.5 (9.6-39.8) | 62.4 (24.0-162.6) | 60.6 (37.6-97.7) | 57.5 (28.7-115.1) | ||
| P valuee | <.001 | <.001 | <.001 | <.001 | ||
| NVs vs NNVsd | 0.6 (0.3-1.4) | 1.8 (0.7-4.9) | 1.2 (0.7-2.1) | 1.3 (0.7-2.7) | ||
| P valuee | .33 | .13 | .50 | .24 | ||
| Smokers vs NVsd | 31.1 (23.8-40.7) | 34.4 (26.4-44.8) | 48.5 (38.6-61.0) | 43.0 (32.8-56.3) | ||
| P valuee | <.001 | <.001 | <.001 | <.001 | ||
Urine biospecimens were collected in person from a stratified probability sample of wave 1 adults who provided a sufficient urine sample and were selected from a diverse mix of 6 tobacco product use groups representing never, current, and recent former (within 12 months) users of tobacco products. Biomarker concentrations below the limit of detection were imputed using a standard substitution formula (limit of detection/√2).
Wave served as the predictor and age, sex, race and ethnicity, and education served as covariates; for NNVs and NVs, there was further adjustment for e-cigarette device types and number of recent puffs. For the wave × group interaction P values, a linear regression model omnibus interaction test adjusted for age, sex, race and ethnicity, and education.
P = .003 for wave × group interaction. Total nicotine equivalents is the molar sum of the imputed values of cotinine and trans-3′-hydroxycotinine in urine.
The data are expressed as the ratio of means (95% CI) for the pairwise between-group comparisons.
From multivariable regressions adjusted for age, sex, race and ethnicity, and education.
P = .005 for wave × group interaction.
P = .06 for wave × group interaction.