Publication bias and public health policy on environmental tobacco smoke.
OBJECTIVE
To examine the tobacco industry's claim that publication bias against negative studies invalidates the risk assessment of environmental tobacco smoke (ETS) conducted by the US Environmental Protection Agency and other reviews of the health effects of ETS.


METHODS
Determination of the number of published original research articles that tested the hypothesis that ETS exposure is associated with adverse health effects and that reported statistically significant ("positive") or nonsignificant ("negative") results; the number of articles that concluded that ETS is a health risk; and unpublished studies on the effects of ETS on health.


METHODS
Articles identified by a computerized search of the medical literature supplemented with material obtained from the tobacco industry and hand searching. Articles were classified as peer-reviewed journal articles or articles from sponsored symposia.


METHODS
The statistical significance of results reported in the article and whether or not the article concluded that ETS exposure is a health risk.


RESULTS
More symposium articles than journal articles were reviews (46% vs 6%; P = .0001). More original journal articles than original symposium articles reported the use of statistical tests (96% vs 54%; P = .0001). Of articles with statistical analyses, similar proportions of journal articles and symposium articles reported statistically significant results (57% vs 47%; P = .329). The conclusions of 80% of the original journal articles were positive, compared with 51% of the original symposium articles (P = .006).


CONCLUSIONS
There is no publication bias against statistically nonsignificant results on ETS in the peer-reviewed literature. The high proportion of articles in symposia that reach the conclusion that ETS is not harmful primarily results from the inclusion of review articles.
Bero
L A
LA
Institute for Health Policy Studies, University of California-San Francisco 94109.
Glantz
S A
SA
Rennie
D
D
D006291:Health Policy; D017712:Peer Review, Research; D017594:Publication Bias; D011643:Publishing / Q000706:statistics & numerical data; D012307:Risk Factors; D014028:Tobacco Smoke Pollution / Q000706:statistics & numerical data
D014028:Tobacco Smoke Pollution