Publication bias in the pulmonary/allergy literature: effect of pharmaceutical company sponsorship.

Background: A publication bias exists towards positive results in studies funded by pharmaceutical companies.

Objectives: To determine whether drug studies in the pulmonary/allergy literature also demonstrate a publication bias towards more favorable results when a pharmaceutical company funds the study.

Methods: We reviewed all original articles published in seven pulmonary and allergy journals between October 2002 and September 2003. Included in the review were studies of inhaled corticosteroids (oral or nasal), long- or short-acting bronchodilators, or leukotriene receptor antagonists. Articles with funding from a pharmaceutical company and/or one or more authors employed by a pharmaceutical company were considered pharmaceutical company-sponsored studies. The remaining studies were considered not sponsored by a pharmaceutical company. Results were compared to ascertain whether positive results were obtained more frequently in the company-sponsored studies.

Results: Of the 100 articles included in this review 63 were considered pharmaceutical company-sponsored research. Results favorable for the drugs studies were significantly more common in those funded by a pharmaceutical company (98% vs. 32%).

Conclusions: In the pulmonary and allergy literature, as in other fields, there is a publication bias towards positive results in pharmaceutical company-sponsored research.