Association of industry sponsorship to published outcomes in gastrointestinal clinical research

Background & Aims: Recent years have seen an increase in industry sponsorship of clinical trials throughout medicine. We conducted a study to evaluate the association of industry sponsorship to published outcomes in gastrointestinal (GI) clinical research. Our aims were (1) to evaluate the trends in the source of funding for GI clinical research during the period from 1992 to 2002-2003, (2) to determine whether the source of study funding predicted the likelihood that a study would publish results that favor the drug or device being tested, and (3) to determine whether differences exist in the methodologic quality of the investigational study methods used in studies funded by private industry versus other sources. Methods: We selected all clinical studies evaluating a drug or device from 4 prominent GI journals (Gastroenterology, The American Journal of Gastroenterology Hepatology and Gastrointestinal Endoscopy). All studies were abstracted by using a standardized data abstraction form. We evaluated the trends in funding source for studies published during the years 1992, 2002, and 2003. All selected studies were scored for methodologic quality by using a previously validated scoring system. The percentage of studies that reported outcomes that favored the device or drug being tested against the standard therapy or placebo was determined for each funding source. A funnel plot was constructed to assess for the presence of negative publication bias. Results: A total of 6326 studies were reviewed. For the 1992 trend data, 1860 studies were reviewed, and 135 were selected for inclusion in the study. Ninety-five studies were studies involving the investigation of drugs, and 40 studies involved the testing of a device. For the 2002-2003 data 4466 studies were reviewed, and 315 were selected for inclusion in the study. Two hundred twenty-two studies were clinical trials involving the investigation of drugs, and 93 were clinical trials involving devices. In comparing 1992 to 2002, the percentage of studies funded by industry sources more than doubled from 10% to greater than 28% of the total studies assessed. There was an associated decline in the proportion of studies with funding from non-industry sources during this period (62% to less than 48%). The percentage of studies that did not disclose a funding source fell modestly from 28% to 24%. We found that 86% of studies funded by private industry reported a result favorable to the study drug or device, and 83% of studies funded by academic sources reported a result favorable to the study drug or device (P = .572). On average, studies funded by private industry had a higher methodology score than studies funded by traditional academic sources (75 of 100 vs 65 of 100; P = .005). Analysis of the funnel plot did not reveal evidence of bias against the publication of small studies with insignificant results. Conclusions: The proportion of research funded by industry has more than doubled during the last decade and currently comprises almost half of the funding for GI clinical research. Industry-sponsored studies are, on average, of superior methodologic quality to studies funded by other sources. Industry-sponsored studies in leading GI journals were no more likely than other studies to publish results that favored the study sponsor, although an extremely high percentage of all studies in these journals reported positive results. There has been only a modest decline in studies not acknowledging a funding source.