Table 2.

Relationship between different sequencing patterns and age of onset of substance use

Sequence	C (n = 19)a	D (n = 24)a	E (N = 17)a	F (N = 20)b	*P-value
Age started (mean ± SD)	16.15 ± 4.34	17.04 ± 4.92	17 ± 3.77	12.05 ± 3.94	<  0.0001

C (sequencing C): tobacco-opium-MA; D (sequencing D), tobacco-opium-heroin-MA; E (sequencing E): tobacco-alcohol-opium-heroin-MA; and F (sequencing F), tobacco-alcohol-cannabis-opium-heroin-MA.

MA methamphetamine

Dissimilar values (superscripts a and b) of each row are significantly different.

*Values were analyzed by one-way analysis of variance (ANOVA); values are mean ± SD