Alcohol Marketing, Adolescent Drinking, and Publication Bias in Longitudinal Studies : A Critical Appraisal Using Meta-Analysis

This paper presents a meta-analysis of prospective cohort (longitudinal) studies of alcohol marketing and adolescent drinking. The paper provides a narrative summary of 21 longitudinal studies, and 12 of these are selected for inclusion in the meta-analysis. Each study surveyed a sample of youth to determine baseline drinking status and marketing exposure, and re-surveyed the youth to determine subsequent drinking outcomes. Logistic analyses provide estimates of the log-odds ratio for effects of baseline marketing on drinking at follow-up. Two meta-samples are analyzed: 23 effect-size estimates for drinking onset (initiation); and 40 estimates for drinking behaviors (frequency, amount, binging). Marketing methods include ads in mass media (TV, magazines), promotion portrayals (branded merchandise, movie displays), and subjective evaluations (liking of ads). Publication bias is assessed using funnel plots that account for "missing" studies, bivariate regressions (Egger test), and multivariate regressions that account for study heterogeneity, publication bias, journal quality, and data dependencies. The empirical results are consistent with publication bias, misspecification in some studies, and lack of a genuine effect, especially for mass media. The paper also discusses the issue of "dissemination bias" in the use of research results by investigators and health policy interest groups