The present study is based on the 1998 Student Drug Use Survey in the Atlantic Provinces, a self-reported anonymous survey of students in grades 7, 9, 10 and 12 of the public school systems in New Brunswick, Nova Scotia, Prince Edward Island, and Newfoundland and Labrador.4,16,17,18
The 1998 survey was the second application of a protocol developed and pilot tested in 1994/95.19
Ethics approval was obtained from the Dalhousie University Faculty of Medicine Ethics Committee. The sample design was a cluster sample of randomly selected classes stratified by grade and by either health region (in Nova Scotia and Newfoundland) or school district or board (in New Brunswick and PEI).
The survey used a computer-scannable instrument of 94 items. The methods to assess validity and reliability of the survey are reported elsewhere.20
A test-retest took place in Nova Scotia in March 1998, with an initial sample of 240 students in grades 7, 9, 10 and 12, yielding 225 completed test-retest surveys paired on encoded unique identifiers. The test-retest revealed fair to good agreement for medical stimulant use in the 30 days before the survey and for medical and nonmedical stimulant use in the 12 months before the survey (kappa values 0.68, 0.60 and 0.62 respectively).21
Nonmedical stimulant use in the 12 months before the survey was defined as an affirmative response to the question “In the past 12 months, have you taken stimulants (Benzedrine, Dexedrine, speed, uppers, bennies, pep pills) without a prescription or without a doctor telling you to do so?” Medical stimulant use in the 12 months before the survey was defined as an affirmative response to the question “In the past 12 months, have you taken stimulants (Benzedrine, Dexedrine, Ritalin, Cylert, diet pills) as prescribed for you by your doctor?” Medical stimulant use in the month before the survey was defined as an affirmative response to the question “In the past 30 days, how often did you usually take stimulants (Benzedrine, Dexedrine, Ritalin, Cylert, diet pills) as prescribed for you by your doctor?”
The diversion of prescribed stimulants was defined as an affirmative response to any of the following questions: “Have you ever given any of your stimulant pills to friends? Have you ever sold any of your stimulant pills? Have any of your stimulant pills ever been taken away from you against your will (by force or threats)? and Have any of your stimulant pills ever been stolen from you?”
The statistical analysis took into account the stratified cluster sample design. The prevalence estimates were weighted according to the number of students responding in each stratum and the total number of students enrolled in each stratum. The extent of ever giving, selling, or experiencing coercion or theft was expressed as proportions of students who reported medical stimulant use in the year before the survey. The standard errors used to compute the 95% confidence intervals (CIs) were adjusted for the intracluster correlation by means of the Kish design effect.22
Considered as potential risk factors for stimulant use were sex, grade, province, any alcohol use, any cigarette smoking and any cannabis use. The proportions of students reporting use and non-use of stimulants were compared using logistic regression analysis, initially with unadjusted odds ratios (ORs) and subsequently with adjusted ORs in multivariate models. Statistical significance was set at p < 0.05 with Bonferroni adjustment for the number of variables in the multivariate models, which resulted in a p value of 0.008 or 0.01 depending on the model.
Finally, the influence that the number of students who gave some of their prescribed stimulant medication had on nonmedical stimulant use was determined at the school class and individual student levels, using multivariate logistic regression analysis. Giving and selling prescribed medication were assessed in separate multivariate models because of collinearity. The samples of students in the 2 mainland provinces, and of those in the 2 island provinces, were combined in order to preserve an adequate sample size according to place.