Meta-analysis of studies of passive smoking and lung cancer: effects of study type and continent

Int J Epidemiol. 2007 Oct;36(5):1048-59. doi: 10.1093/ije/dym158. Epub 2007 Aug 9.

Abstract

Background: To calculate a pooled estimate of relative risk (RR) of lung cancer associated with exposure to passive smoking in never smoking women exposed to smoking spouses. This study is an updated meta-analysis that also assesses the differences between estimated risks according to continent and study type using meta-regression.

Methods: From a total of 101 primary studies, 55 studies are included in this meta-analysis, of which, 7 are cohort studies, 25 population-based case-control and 23 non-population-based case-control studies. Twenty previously published meta-analyses are also reviewed. Fixed and random effect models and meta-regression are used to obtain pooled estimates of RR and P-value functions are used to demonstrate consistency of results.

Results: The pooled RR for never-smoking women exposed to passive smoking from spouses is 1.27 (95% CI 1.17-1.37). The RR for North America is 1.15 (95% CI 1.03-1.28), Asia, 1.31 (95% CI 1.16-1.48) and Europe, 1.31 (1.24-1.52). Sequential cumulative meta-analysis shows no trend. There is no strong evidence of publication bias.

Conclusions: The abundance of evidence, consistency of finding across continent and study type, dose-response relationship and biological plausibility, overwhelmingly support the existence of a causal relationship between passive smoking and lung cancer.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Epidemiologic Methods
  • Female
  • Humans
  • Lung Neoplasms / epidemiology
  • Lung Neoplasms / etiology*
  • Male
  • Risk Assessment
  • Tobacco Smoke Pollution / adverse effects*
  • Tobacco Smoke Pollution / analysis

Substances

  • Tobacco Smoke Pollution