Psychosocial factors associated with smoking and drinking among Japanese early adolescent boys and girls: Cross-sectional study

Table 2 Prevalence of smoking by grade

	None		1–2 times		Sometimes		Once a week		More than 2–3 times a week
	N	(%)	N	(%)	N	(%)	N	(%)	N	(%)
Total^a	2713	(93.5)	84	(2.9)	66	(2.3)	7	(0.2)	32	(1.1)
Boys	1350	(92.1)	47	(3.2)	41	(2.8)	4	(0.3)	24	(1.6)	^**b
Girls	1363	(94.9)	37	(2.6)	25	(1.7)	3	(0.2)	8	(0.6)
Grade^a											^**d
7th	843	(95.9)	18	(2.0)	15	(1.7)	2	(0.2)	1	(0.1)
Boys	426	(95.7)	9	(2.0)	8	(1.8)	1	(0.2)	1	(0.2)
Girls	417	(96.1)	9	(2.1)	7	(1.6)	1	(0.2)	0	(0)
8th	935	(92.9)	35	(3.5)	21	(2.1)	4	(0.4)	12	(1.2)	^**e
Boys	449	(90.5)	20	(4.0)	14	(2.8)	3	(0.6)	10	(2.0)	^*c
Girls	486	(95.1)	15	(2.9)	7	(1.4)	1	(0.2)	2	(0.4)
9th	935	(92.0)	31	(3.1)	30	(3.0)	1	(0.1)	19	(1.9)	^***f
Boys	475	(90.5)	18	(3.4)	19	(3.6)	0	(0)	13	(2.5)
Girls	460	(93.7)	13	(2.6)	11	(2.2)	1	(0.2)	6	(1.2)

Prevalence of tobacco use in the last six months among Japanese adolescent boys and girls by grade are shown.
Significant at * p < 0.05; ** p < 0.01; *** p < 0.001 (two-tailed).
^a Does not total 2,923 due to missing data. (N = 2,902)
^b In the two-independent-sample tests by the Mann-Whitney U test among gender, the prevalence among boys was significantly higher than among girls.
^c In 8th graders, the prevalence among boys was significantly higher than among girls.
^d In the multiple comparison tests by the Kruskal Wallis test, there was significant difference among grades.
^e In the two-independent-sample tests by the Mann-Whitney U test between each of the two grades, the prevalence among 8th graders was higher than among 7th graders.
^f The prevalence among 9th graders was higher than among 7th graders.

ISSN: 1751-0759