Confounding in longitudinal studies in addiction treatment research.

ABSTRACT: Background: The effectiveness of treatment for people with substance use disorders is usually examined using longitudinal cohorts. In these studies, treatment is often considered as a time-varying exposure. The aim of this commentary is to examine confounding in this context, when the confounding variable is time-invariant and when it is time-varying. Method: Types of confounding are described with examples and illustrated using path diagrams. Simulations are used to demonstrate the direction of confounding bias and the extent that it is accounted for using standard regression adjustment techniques. Results: When the confounding variable is time invariant or time varying and not influenced by prior treatment, then standard adjustment techniques are adequate to control

SUBMITTER: Pierce M 

PROVIDER: S-EPMC5360166 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature