Non-Medical Drug use Among Adolescent Students: Highlights from the 1999 Ontario Student Drug Use Survey

Adlaf E.M., CMAJ: 162(12), 16771680

Background

During the 1990s, rates of non-medical drug use among adolescents escalated. We assessed data from 5 cycles of the Ontario Student Drug Use Survey for overall trends in the proportion of students reporting illegal drug use between 1991 and 1999.

Methods

The survey is a repeated, crosssectional, 2-stage cluster-design survey of students enrolled in grades 7, 9, 11 and 13. Outcome measures were prevalence of use of 17 drugs, including alcohol and tobacco, over the 12 months preceding the survey.

The start of the 1990s witnessed a renewed cycle of rising drug use by adolescents. This resurgence has been fairly global, with increases documented in the United States, Australia, Europe and Canada.

For example, in the United States between 1991 and 1999, the proportion of students who reported using marijuana in the year before being surveyed increased from 6.2% to 16.5% among those in grade 8, from 16.5% to 32.1 % among those in grade 10 and from 23.9% to 37.8% among those in grade 12. The use of cigarettes in the 30 days before the survey among students in the 3 grades increased from 14.3% to 17.5%, from 20.8% to 25.7% and from 28.3% to 34.6% respectively. Similar increases have been noted in Canadian samples.

Results

The total number of respondents in grades 7, 9, 11 and 13 over the years 1991-999 ranged from 2868 to 3990, with student completion rates (i.e., completions'eligible students) ranging from 76% to 83%. Reasons for noncompletion included absenteeism (about 14%) and absence of parental consent (about 9%).

The prevalence of episodes of heavy drinking (consumption of 5 or more drinks on a single occasion at least once during the 4 weeks before the survey) also increased over the study period. The proportion of students reporting heavy drinking episodes between 1991 and 1999 was as follows: 22.0% in 1991, 17.7% in 1993, 20.5% in 1995, 24.3% in 1997 and 28.2% in 1999.

Moreover, the prevalence of frequent heavy drinking episodes (consumption of 5 or more drinks on a single occasion 4 or more times during the 4 weeks preceding the survey) also increased: 5.5% in 1991, 3.7% in 1993, 4.2% in 1995, 5.3% in 1997 and 7.0% in 1999.

Despite increases in the prevalence of drug use, 26.8% of the students in 1999 reported no use of drugs (including alcohol and tobacco) during the year before the survey, and another 23.9% restricted their use to alcohol. Just over 1 in 3 (38%) reported use of an illicit substance during the year before the survey.