A meta-analysis of worldwide studies demonstrates an association between schizophrenia and tobacco smoking behaviors

Jose De Leon, Francisco J. Diaz

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1005 Scopus citations


A meta-analysis of worldwide studies, found by a 10-year literature follow-up and/or by searching PubMed, was performed. Forty-two studies across 20 nations consistently demonstrated an association between schizophrenia and current smoking (weighted average odds ratio, OR = 5.9; 95% confidence interval, CI 4.9-5.7). In 32 male studies across 18 nations, the weighted average OR was 7.2 (CI, 6.1-8.3). In 25 female studies across 15 nations, the weighted average OR was 3.3 (CI, 3.0-3.6). The association between schizophrenia and current smoking remained after using severe mentally ill controls (18 studies across 9 countries, weighted average OR was 1.9, CI 1.7-2.1) and controlling for other variables (3 studies, adjusted ORs ranged 2-3). Heavy smoking (6 studies across 4 countries, ORs ranged 1.9-6.4) and high nicotine dependence were more frequent in smokers with schizophrenia versus the general population. There was no consistent evidence that heavy smoking or high nicotine dependence was more frequent in smokers with schizophrenia versus severe mentally ill controls. Cessation rates were lower in schizophrenia smokers versus the general population. Schizophrenia patients had a higher prevalence of ever smoking than the general population (9 studies across 6 countries, weighted average OR = 3.1, CI 2.4-3.8) and than severe mentally ill patients (5 studies across 5 countries, OR = 2.0, CI 1.6-2.4). Moreover, in two studies adjusting for confounders schizophrenia patients had an increased risk of starting daily smoking than controls. Thus, people who are going to develop schizophrenia have risk factors that make them more vulnerable to start smoking.

Original languageEnglish
Pages (from-to)135-157
Number of pages23
JournalSchizophrenia Research
Issue number2-3
StatePublished - Jul 15 2005

Bibliographical note

Funding Information:
Preliminary early versions of this article were presented by Dr. de Leon as lectures at John Umstead Hospital, Butner, NC on 8/29/02 and Burghölzli Hospital in Zurich, Switzerland on 7/12/03. Dr. Diaz was partially supported by the Dirección de Investigaciones of the Universidad Nacional, Medellin, Colombia (grants 030802738 and Apoyo a Grupos Reconocidos Colciencias 2004). Margaret T. Susce, R.N., M.L.T., and Maria Johnson, R.N., helped with editing of this article. Raimo K.R. Salokangas, MD, provided prevalences from his study published in Finnish. Terry Kupra, PhD, provided schizophrenia data from a Canadian study ( Gerber et al., 2003 ) that did not describe separated schizophrenia data. Warning for researchers who have conducted studies not included in this meta-analysis: The authors are aware that PubMed is biased against articles published in non-English language. To avoid this bias in future updates of this meta-analysis, the authors will be willing to review published studies sent to them from any country (all medical or scientific journals will be accepted). Please make sure to include an English or Spanish version of the article and enough information about smoking prevalences in the general population of that region or country.

Copyright 2008 Elsevier B.V., All rights reserved.


  • Logistic regression
  • Nicotine
  • Schizophrenia
  • Smoking
  • Tobacco

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Biological Psychiatry


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