Table 2.

Polynomial logistic regression predicting membership in 10-year drug use trajectory groups (N=504)

	Model 1: Main effects			Model 2: Interaction effects
	Remains high (vs. Remains low)	Decreases then increases (vs. Remains low)	Increases then decreases (vs. Remains low)	Remains high (vs. Remains low)	Decreases then increases (vs. Remains low)	Increases then decreases (vs. Remains low)
	Estimate	Estimate	Estimate	Estimate	Estimate	Estimate
Intercept	−3.229	−1.270	−1.301	−4.019	−1.886	−1.741
First drug treatment as young adult (vs. older adult)	1.345 c	0.417	0.888 a	2.525 c	1.490 a	1.172
Male (vs. female)	−0.502	−1.142 c	−1.278 b	−0.009	−0.838	−0.310
White race/ethnicity (vs. all others)	0.371	0.021	−0.251	0.423	−0.008	−0.209
≥High school (vs. < high school)	−0.144	0.312	0.155	−0.145	0.266	0.220
Married (vs. not married)	−0.585	−0.202	−0.292	−0.598	−0.202	−0.027
Project
CTE (vs. TPROC)	−0.878	0.692	0.392	−0.959	0.675	0.333
METH (vs. TPROC)	−0.284	−0.046	0.257	−0.376	−0.103	0.267
TUE (vs. TPROC)	0.578	−0.159	0.648	0.574	−0.291	0.724
Primary drug type is heroin (vs. all others)	2.398 c	0.626	1.393 a	2.552 c	0.577	2.279 b
Age at 1st arrest (continuous)	0.048	0.034	−0.021	0.054	0.039	−0.011
Age at 1st use (continuous)	−0.018	−0.040	−0.050	−0.017	−0.033	−0.052
Over 10 yrs after first drug treatment
Mos incarcerated (continuous)	−0.040 a	0.014	−0.007	−0.021	0.025a	−0.029
Mos in drug treatment (continuous)	0.003	−0.019	0.003	0.012	0.012	−0.037
Mos employed (continuous)	−0.0006	−0.005	0.002	0.005	−0.011	0.003
Interactions: First drug treatment as young adult (vs. older adult) X
Male (vs. female)	--	--	--	−0.841	−0.704	−1.508
Primary drug type is heroin (vs. all others)	--	--	--	−0.263	0.002	−1.697
Mos incarcerated over 10 years after 1st treatment (continuous)	--	--	--	−0.025	−0.016	0.034
Mos in drug treatment over 10 yrs after 1st treatment (continuous)	--	--	--	−0.022	−0.065 a	0.049
Mos employed over 10 yrs after 1st treatment (continuous)	--	--	--	−0.009	0.008	−0.001

^ap < 0.05.

^bp < 0.01.

^cp < 0.001.