. 2021 Jan 12;4(1):e2032757. doi: 10.1001/jamanetworkopen.2020.32757

Table. Participant Characteristics.

Variable	No. (%)^a
Female sex	39 (32.8)
Age, mean (SD), y	42.1 (14.4)
Race/ethnicity
White	35 (30.2)
Black	46 (39.7)
Asian	9 (7.8)
Multi-racial	12 (10.3)
Other^b	14 (12.1)
Hispanic	23 (19.8)
Tobacco product use characteristics
Ever combustible cigarette smoking^c	105 (88.2)
Current e-cigarette vaping status^d	66 (55.5)
Current other tobacco product use^e	27 (25.0)
Biomarkers, mean (SD)
Carbon monoxide, ppm	6.4 (5.9)
Cotinine semiquantitative level^f	4.0 (1.6)
Combustible cigarettes
Age started smoking regularly, mean (SD), y^g	18.7 (6.9)
Current cigarettes/d, mean (SD)^h	11.0 (6.8)
Cigarettes/d when smoking heaviest, mean (SD)^g	17.8 (10.9)
No. of days smoked in past 30 d^h	23.4 (10.7)
FTCD, mean (SD)^h	4.4 (2.2)
Usually smoke(d) menthol cigarettes^g	47 (53.4)
e-Cigarettes
PSECD, mean (SD)ⁱ	10.1 (4.9)
Puffs per day, mean (SD)ⁱ	85.5 (90.4)
Nicotine concentration typically used, mean (SD), mg/mLⁱ	29.3 (20.6)
Duration of e-cigarette use, mean (SD), mo^j	21 (16.2)
No. of days vaped in past 30 dⁱ	23.4 (8.6)
e-Cigarette device type typically used^j
Cig-a-like	2 (3.3)
Tank/pen	5 (8.2)
Advanced personal vaporizer/mod	11 (18.0)
Pod-based	34 (55.7)
Other	9 (14.8)
Preferred e-cigarette flavor^j
Fruit	28 (45.9)
Dessert	7 (11.5)
Mint	6 (9.8)
Menthol	9 (14.8)
Tobacco	9 (14.8)
Other	2 (3.3)

Abbreviations: e-cigarette, electronic cigarette; FTCD, Fagerström Test for Cigarette Dependence; PSECD, Penn State Electronic Cigarette Dependence Index.

^{^a}

Overall N = 119. Sample size ranges from 110-119 across variables due to differential patterns of missing data across variables.

^{^b}

Includes American Indian or Alaskan Native, Middle Eastern, Pacific Islander (including Hawaii), and other.

^{^c}

Smoked ≥100 cigarettes lifetime and in the past 30 days (n = 22 were former smokers who did not smoke at all in past month, n = 83 were current [past-month] smokers).

^{^d}

Vaped ≥3 days per week for past ≥2 months.

^{^e}

Past 30-day use of “chewing tobacco, snuff or dip,” “dissolvable tobacco product,” “bidis,” “kreteks,” “regular pipe tobacco,” “snus,” “big cigars,” “little cigars or cigarillos,” or “hookah water pipe.”

^{^f}

Test strip (range, 1–6; 0 = 0-10, 1 = 10-30, 2 = 30-100, 3 = 100-200, 4 = 200-500, 5 = 500-1000, 6 = >1000 ng/mL).

^{^g}

Former or current smokers only (n = 105). Numbers range from 83-105 due to missing data across variables.

^{^h}

Current smokers only (n = 83). Numbers range from 80-83 due to missing data across variables.

^ⁱ

Current users of e-cigarettes only (n = 66). Numbers range from 54-66 due to missing data across variables.

^{^j}

Ever users of e-cigarettes only (n = 64). Numbers range from 54-64 due to missing data across variable.