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Characterizing sponsor-imposed restrictions on disclosing results of clinical trials.
Objective Concern about undisclosed conflicts of interest and associated withholding of trial data by sponsors is growing. An FDA Amendments Act (FDAAA) provision mandating public disclosure of agreements that restrict the principal investigator's (PIs) ability to disclose results became effective on September 27, 2008. ClinicalTrials.gov includes the following categories that were based on published results of surveys of trial sponsors and organizations that conduct trials: short embargo (≤60 days), no content control; longer embargo (>60 days and ≤180 days); no content controll; and other disclosure restrictions. The objective of this study was to characterize the types of sponsor-PI agreements reported to ClinicalTrials.gov and propose options for improving the existing categorization scheme.
Design Entries from all 183 results records posted at ClinicalTrials. gov (as of May 15, 2009) were evaluated, including all full-text descriptions of the Other category.
Results Of the 154 studies for which PIs were not employees of the sponsor, 117 (76%) indicated a restriction: 14 (12%) impose short embargoes, 14 (12%) impose longer embargoes, and 89 (76%) described Other restrictions. Among the 117 studies reporting restrictions, there were 33 phase 1-2 trials and 82 phase 3-4 trials; the majority (111/117) were sponsored by industry. Within the Other category, the following issues were addressed: (1) results communications for multisite studies (54/89); (2) "fixed" delays after study completion, including for publication of multisite studies (40/89); (3) sponsors' rights to review, edit, and/or approve results communications (66/89); and (4) embargoes (80/89). Each sponsor used consistent text for its other entries. (Table 14.)
Table 14. Sponsor-Imposed Restrictions Addressed in Other Category in Results Records Posted at ClinicalTrials.gov (as of May 15, 2009)
Conclusions Of the trials with sponsor-imposed restrictions on results disclosure, 76% were not captured by existing embargo categories at ClinicalTrials.gov. Our analysis suggests that additional categories would more accurately reflect common restrictions for multisite studies, fixed delays, sponsor control of content, and embargoes. Developing improved categories could enhance transparency by providing more consistent, comprehensive descriptions of PI-sponsor agreements.