La. Bero et al., PUBLICATION BIAS AND PUBLIC-HEALTH POLICY ON ENVIRONMENTAL TOBACCO-SMOKE, JAMA, the journal of the American Medical Association, 272(2), 1994, pp. 133-136
Objective.-To examine the tobacco industry's claim that publication bi
as against negative studies invalidates the risk assessment of environ
mental tobacco smoke (ETS) conducted by the US Environmental Protectio
n Agency and other reviews of the health effects of ETS. Design.-Deter
mination of the number of published original research articles that te
sted the hypothesis that ETS exposure is associated with adverse healt
h effects and that reported statistically significant (''positive'') o
r nonsignificant (''negative'') results; the number of articles that c
oncluded that ETS is a health risk; and unpublished studies on the eff
ects of ETS on health. Participants.-Articles identified by a computer
ized search of the medical literature supplemented with material obtai
ned from the tobacco industry and hand searching. Articles were classi
fied as peer-reviewed journal articles or articles from sponsored symp
osia. Main Outcome Measure.-The statistical significance of results re
ported in the article and whether or not the article concluded that ET
S exposure is a health risk. Results.-More symposium articles than jou
rnal articles were reviews (46% vs 6%; P=.0001). More original journal
articles than original symposium articles reported the use of statist
ical tests (96% vs 54%; P=.0001). Of articles with statistical analyse
s, similar proportions of journal articles and symposium articles repo
rted statistically significant results (57% vs 47%; P=.329). The concl
usions of 80% of the original journal articles were positive, compared
with 51% of the original symposium articles (P=.006). Conclusions.-Th
ere is no publication bias against statistically nonsignificant result
s on ETS in the peer-reviewed literature. The high proportion of artic
les in symposia that reach the conclusion that ETS is not harmful prim
arily results from the inclusion of review articles.