Confounding in longitudinal studies in addiction treatment research
نویسندگان
چکیده
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 for confounding bias, provided that in the latter scenario the time-varying form of the variable is used. When the confounder is time varying and affected by prior treatment status (i.e. it is a mediator of treatment), then standard methods of adjustment result in inconsistency. Conclusions: In longitudinal cohorts where treatment exposure is time varying, confounding is an issue which should be considered, even if treatment exposure is initially randomized. In these studies, standard methods of adjustment may result be inadequate, even when all confounders have been identified. This occurs when the confounder is also a mediator of treatment. This is a likely scenario in many studies in addiction.
منابع مشابه
Ethical issues in the conduct of longitudinal studies of addiction treatment.
Many complex ethical issues arise in the day-to-day conduct of longitudinal studies of addiction treatment. These issues are rooted, in part, in the sustained and potentially ambiguous relationship between research staff and study participants, the frequently changing clinical and legal status of study participants, the assertive methods required to generate high follow-up rates, and the numero...
متن کاملThe Effect of Information Therapy on Treatment Adherence among Patients Referred to Addiction Treatment Centers
متن کامل
Confounding of the Comparative Safety of Prenatal Opioid Agonist Therapy.
Prenatal opioid agonist therapy with methadone or buprenorphine prevents maternal illicit opioid use and withdrawal and improves pregnancy outcomes compared to heroin use alone. Historically, methadone has been the first-line opioid agonist therapy for pregnant opioid dependent women; in recent years buprenorphine has become first-line treatment for some opioid dependent pregnant women. While t...
متن کاملFrom Datura stramonium L to Hab-o-shefa: manuscript, animal and clinical studies for the treatment of addiction
Background: Due to the lack of drug dependence prevention processes and the low effectiveness of treatment for the withdrawal of addiction and undesirable side effects of synthetic drugs, moving towards the use of reverse pharmacology to produce a less costly, effective, and low-risk drug is inevitable. Objective: Considering the long history of traditional medicine in Iran in the field of diag...
متن کاملMethodological issues of confounding in analytical epidemiologic studies
Background: Confounding can be thought of as mixing the effect of exposure on the risk of disease with a third factor which distorts the measure of association such as risk ratio or odds ratio. This bias arises because of complex functional relationship of confounder with both exposure and disease (outcome). In this article, we provided a conceptual framework review of confounding issues in epi...
متن کامل