Table 4.

Estimates of probability for four risk behaviors, by age, gender and city

Risk behavior	Hanoi		Shanghai		Taipei
	Male n=3095	Female n=3109	Male n=2893	Female n=3040	Male n=2168	Female n=2158
Smoking
16	9.0bcd	2.6bcd	15.0bcd	5.4bcd	21.7bcd	11.1bcd
18	21.8	3.8	29.2	8.6	32.3	17.0
20	42.6	5.4	47.1	13.7	39.7	21.1
22	59.3	6.9	62.5	21.7	44.6	24.2
24	65.6	7.1	70.1	21.2	48.9	25.3
Drinking
16	16.4acd	6.4acd	21.1acd	11.9acd	22.8 acd	14.8 acd
18	35.4	14.1	38.4	22.2	39.9	28.9
20	59.7	26.7	58.8	39.0	60.0	48.3
22	70.3	36.9	72.1	53.8	69.1	60.7
24	73.1	42.9	78.4	62.0	72.6	67.3
Drug use
16	0.0 abd	0.0 abd	0.1 abd	0.0 abd	0.6 abd	0.4 abd
18	0.2	0.1	0.2	0.1	1.7	1.7
20	0.3	0.1	0.7	0.2	3.0	2.8
22	0.7	0.1	1.3	0.3	4.7	3.7
24	0.8	0.1	1.9	0.7	5.2	5.2
Sexual intercourse
16	0.0 abc	0.0 abc	0.2 abc	0.2 abc	3.4 abc	2.4 abc
18	0.8	0.4	2.6	1.8	13.3	11.1
20	3.6	1.7	11.9	6.2	29.6	25.3
22	9.9	3.4	29.8	16.0	42.7	37.3
24	16.5	6.5	46.5	30.4	55.5	47.2

The probability was estimated by using life-table method, while the difference between behaviors was tested by using Cox regression models controlling for age, residence, education level, school status and economic status.

^a: Compared with smoking p≤0.05;

^b: Compared with drinking p≤0.05;

^c: Compared with drug use p≤0.05;

^d: Compared with sexual behavior p≤0.05.