Isojarvi 2018

Appraisal of: Isojarvi, J., Wood, H., Lefebvre, C., Glanville, J. Challenges of identifying unpublished data from clinical trials: getting the best out of clinical trials registers and other novel sources. Res Synth Methods. 2018;9(4):561-578.

Reviewer(s): 

Monika Mierzwinski-Urban

Melissa Severn

Full Reference: 

Isojarvi, J., Wood, H., Lefebvre, C., Glanville, J. Challenges of identifying unpublished data from clinical trials: getting the best out of clinical trials registers and other novel sources. Res Synth Methods. 2018;9(4):561-578

Short description: 

The aim of this review was to summarize research evidence on how to identify sources of unpublished trial data, how these sources should be searched, and which evolving initiatives may improve access and retrieval of unpublished trial data.

The evidence shows that unpublished trial data can be found in a range of resources including clinical trials registers, regulatory agencies’ websites, health technology assessment agencies’ websites, manufactures’ websites, and submissions for regulatory approval. It has been found that these sources can provide access to additional unique trial data (e.g., primary, secondary outcome information or adverse events data) which might not be available in trial publications such as conference abstracts or journal articles.

The authors did not identify any research which provided a ranked list of resources that should be searched for unpublished clinical trial data, however, they have compiled and presented a list of specific resources that provide access to unpublished data. Also, since there is no one source that would provide access to all trials and since it is not clear how far trials registers overlap and how to best search them, the authors suggest that multiple trial registers should be searched.

The new evolving initiatives such as OpenTrials (no longer active) and OpenTrialsFDA, which strive to enhance access to and retrieval of unpublished trial evidence, have also been identified and described in this review.

Limitations stated by the author(s): 

This review was not a systematic review, therefore, it is possible that other potentially relevant studies might be found via more extensive searches, particularly in languages other than English

This review did not focus on the following areas of clinical trials research:  what systematic reviewers are reporting on how they search trials registers, what systematic reviewers are reporting regarding their use of regulatory agency or CSRs data, what is the evidence of the scale and extent of non-publication of trials

Limitations stated by the reviewer(s): 

The topic of when to search the different sources of unpublished trial data is not explored in depth in this review, however, an ongoing project that may address this topic is being mentioned within the review.

Only published literature was consulted for this review, it is possible that grey literature searches may provide additional information on identifying unpublished clinical trial data.

Study Type: 

Narrative review

Related Chapters: 

Tags: 

• Grey literature

• Ongoing trials