Intervention impact on alcohol use, alcohol harms, and a combination of both: A latent class, secondary analysis of results from a randomized controlled trial

BACKGROUND: Alcohol use and alcohol-related harm (ARH) among adolescents places a substantial burden on health, and public services more generally. To date, attempts to intervene at a universal level have yielded results varying from iatrogenic to null, although some skill-enhancing universal interventions have successfully impacted drinking behaviors. One such intervention is SHAHRP. The present study is a secondary analysis of data from the STAMPP Trial, providing new, and more nuanced findings.

METHODS: A total of 13,914 adolescents (41.7% female) participated in this cRCT where schools were randomly assigned to a control or intervention group. Growth mixture modelling was used to identify trajectory classes from baseline through third follow-up (+33 months) of adolescents on heavy episodic drinking (HED) and ARH. Extracted classes were related to school intervention participation using multinomial logistic regression.

RESULTS: Five trajectory classes of the HED and ARH composite were identified: Low (62%), Late Onset (16%), Early Onset (13%), Delayed Onset (7%), and Unstable (3%). The intervention was most strongly related to Late Onset (OR = 0.50, 95%CI [0.25, 1.01]) and Delayed Onset (OR = 0.55, 95%CI [0.26, 1.16]), although not statistically significant. With classes constructed with ARH only, the Delayed Onset class was significantly related to the intervention (OR = 0.60, 95%CI [0.43, 0.84]).

CONCLUSIONS: These results support those previously reported on the STAMPP Trial and provide a more nuanced insight into the effects of the intervention.