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Searching for unpublished data for Cochrane reviews: cross sectional study
Jeppe Bennekou Schroll1, Lisa Bero, Peter C Gøtzsche
1The Nordic Cochrane Centre, Rigshospitalet, Dept 7810, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark. js@cochrane.dk
BMJ (Clinical Research Ed.)
|April 25, 2013
Summary
Most Cochrane review authors successfully obtained unpublished data from trialists for their research. However, manufacturers and regulatory agencies were infrequent sources, and the study had a low response rate.
Area of Science:
- Medical Research
- Evidence Synthesis
- Scientific Publishing
Background:
- Accessing unpublished data is crucial for comprehensive systematic reviews.
- Cochrane reviews aim to synthesize all relevant evidence, including data not found in published literature.
- Understanding authors' experiences in obtaining unpublished data can identify barriers and facilitators.
Purpose of the Study:
- To investigate the experiences of authors conducting Cochrane reviews.
- To describe the process of searching for, accessing, and utilizing unpublished data.
- To identify common sources and challenges in obtaining unpublished trial data.
Main Methods:
- A cross-sectional study design was employed.
- Data were collected via an online survey from corresponding authors of Cochrane reviews.
- Response frequencies to open and closed questions were analyzed.
Main Results:
- A 36.9% response rate was achieved from 5915 contacted authors.
- Over 75% of respondents searched for unpublished data, with trialists/investigators being the primary source (73.9%).
- Data were obtained in 55.1% of searches, often within a month, and frequently used in reviews (82.0%). Manufacturers and regulatory agencies were uncommon data sources.
Conclusions:
- The majority of Cochrane review authors who sought unpublished data found it valuable, mainly from trialists.
- Low response rates suggest non-respondents may be less likely to have searched for unpublished data.
- Manufacturers and regulatory agencies represent underutilized sources for unpublished data in systematic reviews.
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