a1 Division of Epidemiology, Services and Prevention Research, National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA
a2 Department of Epidemiology and Biostatistics, Michigan State University School of Medicine, East Lansing, MI, USA
a3 Institute for Social Research, University of Michigan, Ann Arbor, MI, USA
a4 National Drug and Alcohol Research Centre, University of New South Wales, Randwick, Australia
a5 Department of Psychology, Wesleyan University, Middletown, CT, USA
a6 National Institute of Mental Health, Bethesda, MD, USA
a7 Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA
a8 National Scientific Research Center (CNRS 5231), Bordeaux, France
a9 Department of Health Care Policy, Harvard Medical School, Boston, MA, USA
Background Although mental disorders have been shown to predict subsequent substance disorders, it is not known whether substance disorders could be cost-effectively prevented by large-scale interventions aimed at prior mental disorders. Although experimental intervention is the only way to resolve this uncertainty, a logically prior question is whether the associations of mental disorders with subsequent substance disorders are strong enough to justify mounting such an intervention. We investigated this question in this study using simulations to estimate the number of substance disorders that might be prevented under several hypothetical intervention scenarios focused on mental disorders.
Method Data came from the National Comorbidity Survey Replication (NCS-R), a nationally representative US household survey that retrospectively assessed lifetime history and age of onset of DSM-IV mental and substance disorders. Survival analysis using retrospective age-of-onset reports was used to estimate associations of mental disorders with subsequent substance dependence. Simulations based on the models estimated effect sizes in several hypothetical intervention scenarios.
Results Although successful intervention aimed at mental disorders might prevent some proportion of substance dependence, the number of cases of mental disorder that would have to be treated to prevent a single case of substance dependence is estimated to be so high that this would not be a cost-effective way to prevent substance dependence (in the range 76–177 for anxiety-mood disorders and 40–47 for externalizing disorders).
Conclusions Treatment of prior mental disorders would not be a cost-effective way to prevent substance dependence. However, prevention of substance dependence might be considered an important secondary outcome of interventions for early-onset mental disorders.
(Received June 11 2008)
(Revised August 18 2008)
(Accepted August 21 2008)
(Online publication December 02 2008)