IJE Advance Access originally published online on August 9, 2007
International Journal of Epidemiology 2007 36(5):1048-1059; doi:10.1093/ije/dym158
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Meta-analysis of studies of passive smoking and lung cancer: effects of study type and continent
School of Population Health, University of Queensland, Australia.
* School of Population Health, University of Queensland, Herston Road, Herston, Queensland 4006, Australia. E-mail: r.taylor{at}sph.uq.edu.au
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Abstract |
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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.
Keywords passive smoking, lung cancer, meta-analysis
Accepted 3 July 2007