Survey participation requests were sent to 709 unique clinical trialists (fig 1); 26 were subsequently excluded from our study population because contact information was invalid (n=18), technical difficulties prevented the author from accessing the survey (n=4), or the author was a secondary user of clinical trial data generated by another research group (n=4). Of the remaining 683 trialists, 317 completed the survey either online (n=306) or by phone (n=11), yielding a response rate of 46%.
Fig 1 Flow chart showing identification and selection of potential survey respondents
Survey respondents did not differ from non-respondents with respect to corresponding author location or affiliation, trial enrolment, or journal in which the article was published (table 1). However, trial funders differed among responders and non-responders (P=0.001), as corresponding authors of trials funded solely by government sources responded more often than corresponding authors of trials funded solely by industry or by mixed funding sources.
Table 1 Comparison of characteristics of survey respondents and non-respondents
More than 90% of respondents were corresponding authors of clinical trials (275 (87%) of primary reports and 20 (6%) of secondary reports of clinical trials), and 22 (7%) were corresponding authors of prospective observational studies. Most respondents were aged 50–64 years, male, received their scientific training in the US or Canada, and had completed their training 10–24 years ago (table 2). Most (83%) were employed by an academic institution, and two thirds of these had reached the rank of full professor. Respondents were professionally productive: in the past three years, 41% had published ≥25 articles, 46% had been awarded four or more grants, and 52% had received more than $1million in direct research support.
Table 2 Sociodemographic and professional characteristics of survey respondents (n=317)
Support for and prevalence of data sharing
Overall, 278 (88%) of respondents supported data sharing. Specifically, 236 (74%) thought that, in principle, sharing de-identified data through a data repository should be mandatory. Furthermore, 229 (72%) thought that investigators should be required to share de-identified data upon individual request.
In practice, only 56 (18%) respondents were required by their research funder to deposit their trial data in a repository, and 32 of the 56 (57%) had thus far deposited the data. Similarly, 149 (47%) had received an individual request to share their clinical trial data, and 115 (77%) of these had granted at least one request and 56 (38%) had denied at least one request. The most common reasons for data requests were for systematic review or meta-analysis (n=85 (57%)), for subgroup analysis of the originally published study (n=58 (39%)), and to pursue novel research questions (n=47 (32%)). Among the respondents, 101 (32%) had made a request for clinical trial data of another investigator: 81 of 101 (80%) had at least one request granted, and 49 (49%) had at least one request declined.
Respondents varied in their beliefs about right of first use of clinical trial data. Five (2%) indicated that clinical trial data should be made available to investigators external to the study team immediately on trial completion, 109 (34%) stated that it should be within one to two years of trial completion, 97 (31%) stated that it should be within three to five or more years of trial completion, while 106 (33%) indicated that there should be no time limit and that the right of first use should extend until the main findings are accepted for publication.
Concerns with data sharing through repositories
Respondents identified potential major and minor concerns with data sharing through repositories. The most common concerns related to appropriate data use (n=205 (65%)), but investigator and funder interests (n=129 (41%)) and protection of research subjects (n=91 (29%)) were also common concerns. Specific concerns, and whether they were indicated to be major or minor, are displayed in fig 2.
Fig 2 Major and minor concerns with data sharing through repositories described by 317 survey respondents, grouped by overarching concern related to appropriate data use, investigator or funder interests, and protection of research subjects. (The sample (more ...)
Reasons for granting and denying individual data sharing requests
Respondents offered several reasons for sharing data in response to an individual request. The most common reasons cited were related to promoting open science (n=248 (78%)), although academic benefits and recognition (n=133 (42%)) were also often identified. More detailed reasons for granting data sharing requests are displayed in fig 3.
Fig 3 Reasons for granting individual requests to share data described by 317 survey respondents, grouped by overarching reason related to promoting open science, enhancing academic benefit or recognition, and satisfying administrative requirements. (The (more ...)
Similarly, respondents offered several reasons for denying individual requests to share data. The most common reasons cited were related to ensuring appropriate data use (n=233 (74%)). However, protecting investigator or funder interests (n=121 (38%)) and protecting research subjects (n=107 (34%)) were also often cited. More detailed reasons for denying data sharing requests are displayed in fig 4.
Fig 4 Reasons for denying individual requests to share data described by 317 survey respondents, grouped by overarching reason related to ensuring appropriate data use, protecting investigator or funder interests, and protecting research subjects. (The (more ...)