Substance use by adolescents in Cape Town: prevalence and correlates

Purpose: The work reported in this paper was supported by grants from the World Health Organisation Programme on Substance Abuse, the United Nations Development Programme, the South African Medical Research Council, and the Medical Faculty Research Committee of the University of Cape Town.To document the prevalence rates for use of cigarettes, alcohol, and cannabis among high school students in Cape Town, and to investigate whether use of these substances is associated with a set of hypothesized psychosocial correlates.

Methods: A multistage sampling procedure produced a sample of 2930 students in grades 8 and 11 at 39 high schools in Cape Town, who completed a self-administered questionnaire. The questionnaire contained items about whether the students had used various substances and that addressed the potential correlates of interest. We calculated prevalence rates with 95% confidence intervals and constructed a set of generalized estimating equations of use in the past month of cigarettes, alcohol, or cannabis on the hypothesized correlates.

Results: The prevalence rates for previous month (recent) use of cigarettes, alcohol, and cannabis were 27%, 31%, and 7%, respectively. Rates were low for black females. Recent use of each of the substances was significantly associated with the number of days absent and the number of years lived in a city. Repeating a grade was significantly associated with previous month use of cigarettes and alcohol by colored (derived from Asian, European, and African ancestry) students and alcohol use by black grade 8 students (race classifications "colored" and "black" are as defined by the repealed population Registration Act of 1950). Not being raised by both parents was significantly associated with cigarette smoking by black and colored students, alcohol use by colored students, and cannabis use by female students. It was inversely associated with cigarette use by black students.

Conclusions: It is necessary to identify the factors that protect black female adolescents from substance use. It is important to address demographic factors such as race classification and gender analytically if one is to avoid obscuring differences among groups.