Effect of Electronic Cigarettes on Smoking Reduction and Cessation in Korean Male Smokers: A Randomized Controlled Study

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Figure 1.
Consolidated Standards of Reporting Trials flow chart detailing conduct of the study. MHx., medical history; ds., disease; NRT, nicotine replacement therapy; NG, nicotine gum; EC, e-cigarette.
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Figure 2.
Intervention products used in the present study: (A) e-cigarette and cartilage; (B) components of an electronic cigarette,¹ rechargeable battery,² digital button,³ main body, consisting of a controller and an atomizer,⁴ mouthpiece with chamber containing e-cigarette fluid,⁵ and disposable mouthpiece cover; and (C) nicotine gum.
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Figure 3.
Efficacy of smoking cessation according to interventions, electronic cigarette versus nicotine gum. (A) Continuous abstinence rates at 9- to 12-weeks and 9- to 24-weeks; and (B) 7-day PP of abstinence. NS, nonsignificant; PP, point prevalence.

Table 1.

Baseline Characteristics of the Study Subjects

Characteristic	All Subject (n = 150)	EC Group (n = 75)	NG Group (n = 75)	P Value^*
Age, years	42.3 ± 8.3	44.0 ± 7.8	40.7 ± 8.4	.014
Male sex, N (%)	150 (100)	75 (100)	75 (100)	1.000
Education level, N (%)
≤High school	91 (60.7)	51 (68.0)	40 (53.3)	.066
≥College	59 (39.3)	24 (32.0)	35 (46.7)
Marriage status, N (%)
Unmarried	15 (10.0)	5 (6.7)	10 (13.3)	.174
Married	135 (90.0)	70 (93.3)	65 (86.7)
Alcohol user, N (%)	107 (71.3)	55 (73.3)	52 (69.3)	.588
Exercise, N (%)	82 (54.7)	45 (60.0)	37 (49.3)	.189
Total smoking amount, pack-year	21.56 ± 9.71	23.84 ± 9.40	19.28 ± 9.54	.004
Cigarettes per day smoked, pack	1.01 ± 0.37	1.05 ± 0.37	0.96 ± 0.36	.161
Duration of smoking, years	21.98 ± 8.76	23.26 ± 7.60	20.69 ± 9.67	.072
Initial confidence about quitting smoking, score	5.95 ± 2.67	6.12 ± 2.57	5.79 ± 2.77	.447
FTND, score	4.05 ± 2.24	4.00 ± 2.22	4.09 ± 2.27	.799
Number of prior attempts to quit (%)
None	15 (10.0)	10 (13.3)	5 (6.7)	.193
1	31 (20.7)	12 (16.0)	19 (25.3)
≥2	104 (69.3)	53 (70.7)	51 (68.0)

EC, electronic cigarette; NG, nicotine gum; FTND, Fagerström test for nicotine dependence.
↵* P values were calculated by independent t test (for continuous variables) and χ² test (for categorical variables).

Table 2.

Comparison of Continuous Abstinence Rate and 7-Day Point Prevalence of Abstinence in the Two Groups

Outcome	EC Group	NG Group	Crude P Value	Adjusted P Value^*
CAR at 9 to 12 week, (%)	45.3	46.7	.870	.947
CAR at 9 to 24 week, (%)	21.3	28.0	.344	.291
7-day PP of abstinence at 12 week, (%)	65.3	66.7	.863	.602
7-day PP of abstinence at 24 week, (%)	22.7	29.3	.352	.365

EC, electronic cigarette; NG, nicotine gum; CAR, continuous abstinence rates; PP, point prevalence.
↵* Adjusted for confounding baseline factors, such as age and total smoking amount, i.e., pack-year smoked.

Table 3.

Reduction in Smoking Rate and Amount between the Two Groups

Outcome	EC Group	NG Group	P Value^*
12 week
Proportion of subjects with reduced daily cigarettes, N (%)	16 (21.3)	15 (20.0)	.840
Reduction in the mean number of cigarettes consumed in a day	11.06 ± 7.03	12.60 ± 5.65	.509
24 week
Proportion of subjects with reduced daily cigarettes, N (%)	31 (41.3)	19 (25.3)	.038
Reduction in the mean number of cigarettes consumed in a day	6.55 ± 2.87	6.60 ± 3.75	.974

EC, electronic cigarette; NG, nicotine gum.
↵* P values were calculated by independent t test (for continuous variables) and χ² test (for categorical variables).

Table 4.

Frequency of Adverse Events

AE, N (%)	EC Group	NG Group	P Value
Subjects with any AEs^*	5 (6.7)	13 (17.3)	.044
Total AEs	9 (100)	27 (10)
Sore throat^†	—	2 (7.4%)	.497
Oral pain^†	2 (22.2)	5 (18.5)	.442
Cough^†	3 (33.3)	3 (11.1)	1.000
Dry mouth^†	2 (22.2)	2 (7.4)	1.000
Oral ulcer^†	—	—	—
Dizziness^†	—	5 (18.5)	.058
Headache^†	1 (11.1)	2 (7.4)	1.000
Nausea or vomiting^†	1 (11.1)	8 (29.6)	.034
Others^†	—	—	—

AEs, adverse events; EC, electronic cigarette; NG, nicotine gum.
↵* P value was calculated using the χ² test.
↵† P value was calculated using the Fisher-Freeman-Halton extension of Fisher's probability test.