Association between tobacco smoking and opioid use: A meta-analysis.

Background: Tobacco smoking has been shown to be a major risk factor for opioid use and opioid use disorders in several observational studies; however, the results are inconsistent. Thus, this systematic review and meta-analysis of observational studies was conducted to investigate the association between smoking behavior and opioid use and opioid use disorders.
Methods: A systematic literature search of relevant keywords was done in Medline, Embase, Scopus, Web of Science, and Google Scholar up to October 2017. The reference lists of retrieved articles were also examined for inclusion. While random effects meta-analysis was used, pooled odds ratio (OR) and 95% confidence intervals were calculated using Der-Simonian and Laird method, taking into account conceptual heterogeneity. Subgroup analyses were performed using participants and studies' characteristics to assess the sources of heterogeneity.
Results: Ten eligible observational studies (6 cohorts and 4 population-based cross sectional studies), with 175,063 participants, were identified. The pooled OR of opioid use disorders was 8.23 (95% CI: 3.07-22.09) for current smokers compared to nonsmokers; pooled OR for opioid use was 2.51 (95% CI: 1.91-3.28). Opioid use or opioid use disorders were positively associated with earlier age at onset of smoking (pooled OR = 1.66; 95% CI: 1.28-2.16).
Conclusions: The results of this meta-analysis confirmed that tobacco smoking is associated with opioid use and opioid use disorders development. This conclusion has an important public health message for areas with high smoking prevalence and high opioid use and opioid use disorders incidence.
(Copyright © 2018. Published by Elsevier Ltd.)