TABLE 5.

Prevalence and Adjusted Odds Ratios (OR) of Substance Use as a Function of Age of Initiation of Prescription Stimulant Medication

	Two-Week Binge Drinking		Monthly Alcohol Use		Annual Marijuana Use		Annual Cocaine Use		Annual Illicit Drug Index****
Age of Initiation of Prescription Stimulant Medication	%	OR	%	OR	%	OR	%	OR	%	OR
Stimulant medication
No prescribed use (n = 8199)	50.9	1.00	74.3	1.00	36.3	1.00	3.2	1.00	14.3	1.00
Elementary initiation (n = 65)	50.0	0.69	78.1	1.01	50.8	1.49	9.2	2.42	18.5	1.20
Secondary initiation (n = 105)	70.2	1.68*	90.4	2.59**	60.0	1.98**	19.2	4.40***	41.9	3.54***
College initiation (n = 97)	68.0	1.07	94.8	3.60**	78.9	4.30***	22.1	4.46***	51.5	4.41***

Note: Odds ratios (OR) are adjusted for all other predictors in the model and the reference group for each model was students who did not report nonmedical use of stimulants in the past year. All of the models also included gender, race, class year, living arrangement, fraternity/sorority membership, family income, religious affiliation, and grade point average. The odds ratios for these variables were not shown.

^*p < 0.05.

^**p < 0.01.

^***p < 0.001.

^****Illicit drug index consists of summing annual use of cocaine, LSD, other psychedelics, Ecstasy, inhalants, amphetamines, crystal meth, heroin, other opiates, GHB, and Rohypnol.