With respect to MA use and dependence variables, males had earlier onset of MA use -- about 17.7 years of age compared with 19.7 years in females (t=-5.3, p<0.001) -- and had an earlier onset of dependence at about 20.4 years compared with 22.2 years in females (t=-3.6, p<0.001). However, female users were more likely to be dependent on MA (χ21=33.7, p<0.001), to be more severely dependent (χ21=4.9, p=0.03), to use more MA (lifetime episodes; χ21=24.1, p<0.001) and with greater intensity (daily MA pills; χ21=12.4, p<0.001), and frequency (days per month of MA use; χ21=5.1, p=0.02) during periods of heaviest lifetime use. In contrast, duration of MA use, route of MA use, and the severity of MA withdrawal did not differ between groups (although sex-related differences in patterns of MA withdrawal symptoms were noted; see below) (p>0.05; Table 2). With respect to the adjusted model – adjusted for sex difference by controlling for demographic, diagnostic, and MA use variables -- females were more likely to be educated less than 9 years (OR=1.6, 95% CI=1.0-2.4, p=0.034), be widowed, divorced or separated
