Illicit Methylphenidate Use in an Undergraduate Student Sample: Prevalence and Risk Factors

Christian J. Teter, Pharm.D., Sean Esteban McCabe, Ph.D., Carol J. Boyd, Ph.D., Sally K. Guthrie, Pharm.D.

Disclosures

Pharmacotherapy. 2003;23(5) 

In This Article

Methods

The University of Michigan's institutional review board approved the protocol for this study, and all respondents gave informed consent. The study was conducted during a 1-month period between March and April of 2001, drawing on a total undergraduate population of 21,055 full-time students (10,732 women and 10,323 men). A random sample of 3500 full-time University of Michigan undergraduate students was drawn from the Registrar's Office. The students were sent a letter through e-mail describing the study and inviting recipients to self-administer the Student Life Survey. Students were told to access the Web survey by clicking on an e-mail link.

The Student Life Survey was developed and pilot tested in 1993. It draws from items in the Monitoring the Future (MTF) study,[13] the Core Alcohol and Drug Survey,[5] and the College Alcohol Study.[14] Design, procedures, and reliability measures pertaining to the Student Life Survey are described in more detail elsewhere.[15,16]

The survey was designed to collect demographic information, including sex, age, primary ethnic origin, primary religious affiliation, grade point average, fraternity or sorority affiliation, average annual family income, and living arrangements. It also queried students about alcohol and drug use, prescription drug use, sexual behavior, and adverse alcohol- and drug-related consequences.

Illicit drug use was assessed by the following question: "Have you ever used the following types of drugs...(a) in your lifetime, (b) during the past 12 months, or (c) during the past 30 days? Do not include drugs used under a doctor's prescription. (Check all that apply)." The following substances were listed as possible answers: "marijuana, cocaine in any form, LSD, other psychedelics, amphetamines or methamphetamine, crystal meth, Ritalin, downers, tranquilizers, heroin, other narcotics, inhalants, Ecstasy (MDMA), GHB, Rohypnol, anabolic steroids, and other (please specify)." For those drug categories that included a broad range of substances, examples were given for clarification. For example, for "other narcotics," examples given were Vicodin, codeine, Demerol, Percodan, methadone, opium, and morphine. Respondents were given two response categories (yes and no). Endorsement of "yes" was defined as illicit drug use. We created two illicit drug indexes for each student by summing the number of responses indicating that the student had used an illicit substance in the past year or past month, respectively. If respondents indicated they had used a drug in their lifetime, they received a follow-up question asking when they began using the specific drug. The four response categories were elementary school, junior high school, high school, and college. Another index for each student was created to assess the start of drug use before entering college. This index reflected the summation of the number of illicit drugs a student had used in high school or earlier.

To assess prescription drug use, the survey asked the following question: "Based on a doctor's prescription, have you ever used the following types of drugs...(a) in your lifetime? or (b) in the past 12 months?" Five categories of prescription drugs were identified: stimulants (e.g., weight loss pills, Ritalin), sleeping aids (e.g., Halcion), minor tranquilizers (e.g., Valium, Ativan), prescription analgesics (e.g., codeine, Darvon, Tylenol No. 3), and antidepressants (e.g., Prozac, Paxil, Zoloft, Luvox). Respondents were given two response categories (yes and no). An endorsement of "yes" was defined as prescription drug use.

Primary and secondary alcohol-related consequences were assessed by items adapted from national studies of alcohol and drug use among college students.[5,14] For example, primary consequences associated with drinking included missing a class, developing a hangover, damaging property, being hurt or injured, and having unplanned sex. The response scale for each item ranged from 1 (never) to 4 (6 or more times). A primary alcohol-related consequences index was created by summing each respondent's scores for the 23 survey items addressing primary alcohol-related consequences in the past year. Secondary consequences were assessed using 10 questions that explored consequences associated with others' use of alcohol in the past year. Examples were disrupted sleep, experienced an unwanted sexual advance by someone drunk or high, and had to take care of someone with a drinking or drug problem. The response scale for each item ranged from 1 (never) to 5 (10 or more times). A secondary alcohol-related consequences index was created by summing each respondent's scores for the 10 items in this category.

For the survey to qualify as being completed, the student must have answered at least two thirds of the questions, including those addressing demographic characteristics, alcohol use, illicit drug use, prescription drug use both as prescribed by a doctor and not as prescribed, and adverse alcohol- and drug-related consequences. After completing the survey, the student would receive a $10 gift certificate to a local bookstore.

We used 2 tests to compare student demographics, prescription drug use, and alcohol and drug use across three distinct groups, with "the past 12 months" as the time frame. The three groups were as follows: undergraduate students who reported taking methylphenidate not as prescribed by a doctor (illicit use), undergraduate students who reported taking stimulant drugs as prescribed by a doctor, and undergraduate students who reported no stimulant use. In addition to 2 tests, 1-way analyses of variance were used to compare illicit methylphenidate users, prescription stimulant users, and nonstimulant users across several continuous measures. Post hoc pairwise comparisons were conducted using Tukey's honestly significant difference test. We set the a priori at 0.05. Finally, multivariate logistic regression was used to assess factors that might be associated with illicit methylphenidate use, using two separate models for lifetime and past-year use. All analyses were conducted with SPSS software (SPSS Inc., Chicago, IL).

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