The Annals of Applied Statistics

An application of principal stratification to control for institutionalization at follow-up in studies of substance abuse treatment programs

Beth Ann Griffin, Daniel F. McCaffrey, and Andrew R. Morral

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Abstract

Participants in longitudinal studies on the effects of drug treatment and criminal justice system interventions are at high risk for institutionalization (e.g., spending time in an environment where their freedom to use drugs, commit crimes, or engage in risky behavior may be circumscribed). Methods used for estimating treatment effects in the presence of institutionalization during follow-up can be highly sensitive to assumptions that are unlikely to be met in applications and thus likely to yield misleading inferences. In this paper we consider the use of principal stratification to control for institutionalization at follow-up. Principal stratification has been suggested for similar problems where outcomes are unobservable for samples of study participants because of dropout, death or other forms of censoring. The method identifies principal strata within which causal effects are well defined and potentially estimable. We extend the method of principal stratification to model institutionalization at follow-up and estimate the effect of residential substance abuse treatment versus outpatient services in a large scale study of adolescent substance abuse treatment programs. Additionally, we discuss practical issues in applying the principal stratification model to data. We show via simulation studies that the model can only recover true effects provided the data meet strenuous demands and that there must be caution taken when implementing principal stratification as a technique to control for post-treatment confounders such as institutionalization.

Article information

Source
Ann. Appl. Stat., Volume 2, Number 3 (2008), 1034-1055.

Dates
First available in Project Euclid: 13 October 2008

Permanent link to this document
https://projecteuclid.org/euclid.aoas/1223908051

Digital Object Identifier
doi:10.1214/08-AOAS179

Mathematical Reviews number (MathSciNet)
MR2516803

Zentralblatt MATH identifier
1149.62328

Keywords
Principal stratification post-treatment confounder institutionalization causal inference

Citation

Griffin, Beth Ann; McCaffrey, Daniel F.; Morral, Andrew R. An application of principal stratification to control for institutionalization at follow-up in studies of substance abuse treatment programs. Ann. Appl. Stat. 2 (2008), no. 3, 1034--1055. doi:10.1214/08-AOAS179. https://projecteuclid.org/euclid.aoas/1223908051


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Supplemental materials

  • Supplementary material: Supplementary tables for “An application of principal stratificationto control for institutionalization at follow-up in studies of substanceabuse treatment programs”.
  • Supplementary material: Example data for running principal stratification model in “An application of principal stratificationto control for institutionalization at follow-up in studies of substanceabuse treatment programs”.
  • Supplementary material: Example code for running principal stratification model in “An application of principal stratificationto control for institutionalization at follow-up in studies of substanceabuse treatment programs”.