Our results show insufficient knowledge among SR authors about the importance of protocol registration, which was directly reflected in their practice and opinions. About half of the participants seemed that the primary reason for not registering such protocols, that was not knowing that protocols must or should be mandatory. Although some already have registered their protocol for other reason, may be to preserve their rights of the idea or the journal they aim to submit mandate registration beforehand. Other reported reasons for not registering a SR protocol were: registration is not mandatory, carries no benefits, the process is time-consuming, and the fear of idea theft.
In this context, the myth that registration has no benefits or is time-consuming has already been debunked.(23) Before conducting any SR/MA, researchers should scan the field for any ongoing or completed reviews on the same topic.(24, 25) However, many of the individual researchers or research groups do not register or publicly publish the protocols of their ongoing studies; further contributing to the problem of duplication. Accordingly, SR protocol registration has actually become an urgent need that has to be addressed by guideline developers and decision-makers.(23)
Protocol registration is the way to alert different research groups that a related review is being conducted. This will not only help in preventing duplications, saving time and resources but could also open the gate for collaborative work among researchers with shared interests in a certain topic.(23, 26) Protocols may take time to be developed; however, the step of writing the review’s protocol is critical in order to make sure that all investigators are on the same page with avoiding discarded efforts or unintended bias.(23, 26)
Additionally, registration will enhance confidence in the reported results by knowing that the methodology was determined in advance and making sure it was not changed to suit the preference of the authors.(23, 26) Furthermore, a positive association between prospective registration and the methodological quality of SRs has been found.(27) The revised assessment of multiple SRs (R-AMSTAR) of registered reviews was higher than that for non-registered ones.(27) Similarly, the total preferred reporting items for SR/MAs (PRISMA) scores of registered reviews were significantly higher.(27)
In 2013, an online survey was conducted by PROSPERO to evaluate the experience of different users in registering their protocols.(28) Almost all (99%) respondents rated the PROSPERO navigation process as easy or very easy, and the majority (79%) of participants indicated that they had completed the registration form in 60 minutes or less. These findings are inconsistent with the beliefs expressed by the respondents in our sample and eliminates the argument of the registration process being hard or taking too much time. The main reason for such belief could be a preconceived judgment without the actual understanding and knowledge of the process.
Regarding the fear of idea theft, nearly half of the participants suggested that it will be safer for them if the details of the ongoing SR/MA were blocked until the completion of their studies. This option is already available in some databases in order to assure authors as well as to limit the possibility of idea theft problem.
On the other hand, nearly 20% of authors in our study have at least one paper that was registered but not published; either for not managing to finish the study or because they did not get results they anticipated. Furthermore, around 1% of our respondents never managed to publish any of their registered protocols. So, is it fair that someone keeps the idea forever for just thinking about it?.(29)
A recent study by Tsujimoto et al. reported that around 26% of protocols registered in PROSPERO remained unpublished 5.4 years after registration.(30) Further, they reported that funding for SRs was a determining factor in the publication status of registered SRs.(30, 31) As some of the responders in our sample suggested, a possible solution for unpublished papers for registered protocols, is adding an option to allow for direct official contact with authors documented by the database itself. Authors of the ongoing SR/MA may offer a collaboration or even confirm that they will not continue working on this idea. Another possible solution that was suggested by the responders and can be adopted by the databases registering SR protocols is to contact the authors in regular pre-defined intervals to make sure that they are still working on the registered study. If not, the authors can be given an option to either discarded the protocol from the database, to invite other potential authors to continue working on this topic, or to put up a notice that the authors are looking for collaborators that will help them complete the SR.
Some of our participants also suggested that collaboration between different databases registering protocols would be helpful in identifying duplicate ideas, as the same idea might be registered in two different databases by two different author teams. These potentially redundant protocols may pass screening unnoticed and get published, and the authors may find out too late that they have invested their time and efforts to the overlapping study.
The main limitation of this study was related to the low response rate 275/6650 (4.14%), raising the possibility of non-response bias. It is possible that many of the e-mails we sent ended up in the junk/spam folders, or that the e-mail addresses we used were functional but outdated and the authors do not use them anymore, as many e-mails were retrieved from manuscripts published 6 – 8 years ago. Our pilot testing indicated that the length of our questionnaire can be completed within a reasonable time, and we can therefore only speculate that the length of the survey did not contribute to the low response rate.
Due to the limited sample size, our results are not necessarily generalizable (32, 33) in reverse to other some surveys who met good response rate.(34, 35) However, it has to be emphasized that surveys conducted via e-mail generally have lower response rates when compared to in-person surveys (36-39), which is a common problem in all online surveys in general.(32, 33, 36-40) Nonetheless, the conclusions we draw establish a strong foundation for further investigations related to SR protocol registration and provide ideas for fostering registration of such studies.