Researchers identified primary publications (in 2015, in the top 10 medical journals by impact factor) for trials of medicines registered on ClinicalTrials.gov. Fifty-six publications reporting 61 clinical trials were identified. A publicly available policy for data sharing was identified for over half (52%) of the trials, and 9 trials (15%) were confirmed as being eligible for data sharing. Industry sponsors within the top 25 by global sales were more likely to have a publicly available data sharing policy than those below the top 25 (93% vs 10%), and there was a trend towards increased data sharing eligibility (23% vs 4%). Industry sponsors that were members of the Pharmaceutical Research and Manufacturers of America (PhRMA) or the European Federation of Pharmaceutical Industries and Associations (EFPIA) were significantly more likely to have a data sharing policy (94% vs 5%) and confirm trial data sharing eligibility (30% vs 0%) than non-members.
For those trials where data sharing was not available (43%), the most common reasons were that the sponsor does not share individual patient data, the study has ongoing follow-up, or the medicine is not approved by both the European Medicines Agency (EMA) and FDA. The study authors suggest that follow-up for secondary endpoints should not prevent the sharing of data supporting published primary outcomes. Further to this, they state that once a medicine “is in widespread use in one jurisdiction, data sharing of the pivotal trials supporting the registration decision is in the public interest irrespective of the registration status in another jurisdiction”. As of 1 July 2018, manuscripts reporting the outcomes of clinical trials published in International Committee of Medical Journal Editors (ICMJE) member journals are required to include a data sharing statement. Further to this, for clinical trials enrolling participants on or after 1 January 2019, a data sharing plan must be included in the trial’s registration. With these requirements, and as more journals encourage open data, it will be interesting to see whether study sponsors will relax their conditions for data sharing in the future.