Estimating the Causal Effects of Cumulative Treatment Episodes for Adolescents Using Marginal Structural Models and Inverse Probability of Treatment Weighting

Published In: Drug and Alcohol Dependence, v. 136, no. 1, Mar. 2014, p. 69–78

Posted on on March 01, 2014

by Beth Ann Griffin, Rajeev Ramchand, Daniel Almirall, Mary Ellen Slaughter, Lane F. Burgette, Daniel F. McCaffrey

Read More

Access further information on this document at Elsevier Ireland Ltd

This article was published outside of RAND. The full text of the article can be found at the link above.

BACKGROUND: Substance use treatment is rarely a one-time event for individuals with substance use disorders. Sustained reductions in substance use and its related symptoms may result from multiple treatment episodes. METHODS: We use a marginal structural model with inverse-probability-of-treatment weighting to estimate the causal effects of cumulative treatment experiences over a period of 9 months on drug use at the end of 1-year among 2870 adolescents receiving care in community-based treatment settings. During the 9 months, adolescents move in and out of outpatient and residential treatment with periods where they only receive biological drug screening (BDS) or no treatment at all. The use of inverse-probability-of-treatment weighting reduces confounding bias due to observed baseline and time-varying measures over the course of follow-up; weights were estimated using generalized boosted models. RESULTS: Each additional period of treatment (representing at least one day, 1 session, or 1 BDS during the 90 day period between follow-up visits) yielded reductions in average substance use frequency at 1-year relative to no treatment during the 90-day period. For residential treatment it was a 16% decrease (95% CI = −27%, −7%), for outpatient treatment it was a 9% decrease (95% CI = −18%, −0%), and for BDS (with no additional outpatient or residential treatment) it was an 11% decrease (95% CI = −20%, −3%). CONCLUSIONS: Using robust statistical methods, we find promising (albeit preliminary) evidence that additional periods of outpatient and residential treatment, as well as biological drug screening, lead to reductions in substance use outcomes at one year.

This report is part of the RAND Corporation External publication series. Many RAND studies are published in peer-reviewed scholarly journals, as chapters in commercial books, or as documents published by other organizations.

Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.