Nottingham Clinical Trials Unit, The University of Nottingham, Nottingham, UK.
Stroke Trials Unit, Division of Clinical Neuroscience, University of Nottingham, Nottingham, UK.
BMJ Open. 2019 Jan 30;9(1):e025273. doi: 10.1136/bmjopen-2018-025273.
Systematic reviews often rely on the acquisition of unpublished analyses or data. We carried out a nested randomised trial comparing two different approaches for contacting authors to request additional data for a systematic review.
Participants were authors of published reports of prevention or treatment trials in stroke in which there was central adjudication of events. A primary and secondary research active author were selected as contacts for each trial.
Authors were randomised to be sent either a short email with a protocol of the systematic review attached ('Short') or a longer email that contained detailed information and without the protocol attached ('Long'). A maximum of two emails were sent to each author to obtain a response. The unit of analysis was trial, accounting for clustering by author.
The primary outcome was whether a response was received from authors. Secondary outcomes included time to response, number of reminders needed before a response was received and whether authors agreed to collaborate.
88 trials with 76 primary authors were identified in the systematic review, and of these, 36 authors were randomised to Short (trials=45) and 40 to Long (trials=43). Responses were received for 69 trials. There was no evidence of a difference in response rate between trial arms (Short vs Long, OR 1.10, 95% CI 0.36 to 3.33). There was no evidence of a difference in time to response between trial arms (Short vs Long, HR 0.91, 95% CI 0.55 to 1.51). In total, 27% of authors responded within a day and 22% of authors never responded.
There was no evidence to suggest that email format had an impact on the number of responses received when acquiring data for a systematic review involving stroke trials or the time taken to receive these responses.
系统评价通常依赖于获取未发表的分析或数据。我们进行了一项嵌套随机试验，比较了两种不同的方法来联系作者，以请求系统评价的额外数据。
参与者是发表的中风预防或治疗试验报告的作者，这些试验报告中有事件的中央裁决。每个试验选择一个主要和次要的研究活跃作者作为联系人。
作者被随机分配发送附有系统评价方案的简短电子邮件（“简短”）或包含详细信息且未附加方案的较长电子邮件（“长”）。向每位作者最多发送两封电子邮件以获得回复。分析单位为试验，按作者进行聚类。
主要结果是作者是否回复。次要结果包括回复时间、收到回复之前需要的提醒次数以及作者是否同意合作。
在系统评价中确定了 88 项试验，涉及 76 名主要作者，其中 36 名作者被随机分配到“简短”组（试验=45），40 名作者被随机分配到“长”组（试验=43）。收到了 69 项试验的回复。试验组之间的回复率没有差异（短 vs 长，OR 1.10，95%CI 0.36 至 3.33）。试验组之间的回复时间没有差异（短 vs 长，HR 0.91，95%CI 0.55 至 1.51）。总共，27%的作者在一天内回复，22%的作者从未回复。
当涉及获取中风试验系统评价的数据时，没有证据表明电子邮件格式会影响收到的回复数量或收到这些回复所需的时间。
