Sponsor-Imposed Publication Restrictions Disclosed on ClinicalTrials.gov

Abstract

ABSTRACTWe investigated whether sponsor-imposed publication restrictions for ClinicalTrials.gov trials were reasonable, based on consistency with Good Publication Practice 2 (GPP2). ClinicalTrials.gov trial record data were electronically imported (October 7, 2012) and screened for eligibility (phase 2–4, interventional, recruitment closed, results available, first received for registration after November 10, 2009, any sponsor type, investigators not sponsor employees). Two authors categorized restrictions information as consistent or not consistent with GPP2, resolving discrepancies by consensus. Of the eligible trials (388/484, n = 81,768 participants), 80.7% (313/388) had restrictions disclosed, and 92.5% (311/388) were industry-sponsored. Significantly more trials had restrictions that were consistent with GPP2 than not (74.1% [232/313], n = 55,280 participants vs. 25.9% [81/313], n = 19,677 participants; P < .001). Reasons for inconsistency were insufficient, unclear, or ambiguous information (48.1%, 39/81), sponsor-required approval for publication (35.8%, 29/81), sponsor-required text changes (8.6%, 7/81), and outright bans (7.4%, 6/81). Follow-up of trials with insufficient information and a contact email (response rate, 46.9% [15/32]) revealed 2 additional bans. A total of 776 participants had consented to trials that had publication bans. Many, but not all, sponsor-imposed publication restrictions disclosed on ClinicalTrials.gov may be considered reasonable. Sponsors should ensure restrictions are appropriately disclosed. Volunteers should be alerted to any restrictions before consenting to participate in a clinical trial.