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.