TABLE 2.

Observed and Modeled Effect of Substance on Substance Use Milestones

	Time From First Use to Regular Use		Time From First Use to Treatment		Time From Regular Use To Treatment
Observed	Marijuana	Cocaine	Marijuana	Cocaine	Marijuana	Cocaine
Mean (SD)	3.0 (3.4)	2.9 (3.7)	13.8 (8.4)	13.4 (6.6)	10.8 (8.1)	10.5 (6.1)
Modeled	HR (95% CI)	P Value	HR (95%CI)	P Value	HR (95% Cl)	P Value
Unadjusted
Cocaine*	1.02 (0.77, 1.36)	0.87	1.12 (0.84, 1.50)	0.44	1.12 (0.83, 1.49)	.46
Adjusted**
Cocaine*	1.00 (0.70, 1.44)	0.99	1.07 (0.74, 1.56)	0.71	1.06 (0.74, 1.52)	.76
Age at first use	1.03 (1.00, 1.07)	0.05	1.22 (1.17, 1.27)	<.001	1.21 (1.17, 1.27)	<.001
Chronological age	0.97 (0.95, 0.99)	0.01	0.84 (0.81, 0.86)	<.001	0.84 (0.82, 0.87)	<.001
Time from first use to regular use	NA	NA	0.96 (0.92, 1.00)	0.04	1.19 (1.14, 1.25)	<.001

Abbreviations: HR, hazard ratio; CI, confidence interval; NA, not applicable

^*Marijuana was selected as the reference group.

^**Models are adjusted for cocaine, age at first use, chronological age, and time from first use to regular use (i.e., addiction rate).