The timing of outcome measurement is not usually defined in systematic review protocols registered in PROSPERO

ID: 

382

Session: 

Poster session 3

Date: 

Tuesday 18 September 2018 - 12:30 to 14:00

All authors in correct order:

Tsujimoto Y1, Kataoka Y2, Tsutsumi Y3, Tsujimoto H2, Papola D4
1 Department of Nephrology and Dialysis, Kyoritsu Hospital, Hyogo, Japan
2 Hospital Care Research Unit, Department of Respiratory Medicine, Hyogo Prefectural Amagasaki General Medical Center, Hyogo, Japan
3 Department of Emergency Medicine, National Hospital Organization Mito Medical Center, Ibaraki, Japan
4 WHO Collaborating Centre for Research and Training in Mental Health and Service Evaluation, Department of Neuroscience, Biomedicine and Movement Sciences, Section of Psychiatry, University of Verona, Italy
Presenting author and contact person

Presenting author:

Yasushi Tsujimoto

Contact person:

Yasushi Tsujimoto
Abstract text
Background:
Systematic review (SR) authors should define when outcomes are measured. If not pre-specified, this may introduce bias into the selection of reported results. However, there has been no investigation into how often authors define the timing of outcome measurement and whether or not this is associated with the reporting of statistical significance.

Objectives:
We aimed to describe the definition of the timing of outcome measurement and to examine whether pre-specification is associated with the reporting of statistical significance in SRs registered in PROSPERO.

Methods:
All SR protocols for interventional randomized controlled trials (RCTs) that were registered in PROSPERO by 31 December 2014 were eligible. We excluded Cochrane protocols, SRs with network meta-analyses, individual patient data meta-analyses and SRs without meta-analysis. We identified publications using the authors' names and keywords for participants or interventions in PROSPERO via PubMed and Google Scholar. We regarded the timing of outcome measurement to be pre-specified when the authors defined this for all primary outcomes. We described the proportion of SR protocols defining the timing of outcome measurement. We further examined the association between defining the timing of outcome measurement and the reporting of statistical significance using a multivariable logistic regression model to adjust for year of registration, number of included RCTs, number of primary outcomes, multinational collaboration and funding.

Results:
We included a total of 379 SR protocols. Of these, 209 full publications and nine conference abstracts were published before February 2018. Eighty-five protocols (22%) defined the timing of outcome measurement. The proportion did not change from 2011 to 2014 (P for trend = 0.51). Defining the timing of outcome measurement in the protocol was not associated with reporting of statistical significance (adjusted odds ratio 1.48, 95% confidence interval 0.61 to 2.54).

Conclusions:
The timing of outcome measurement was not usually defined among SRs registered in PROSPERO. The present study found no evidence to suggest that defining the timing of outcome measurement reduced the reporting of statistical significance in the publication.

Patient or healthcare consumer involvement:
None.

Relevance to patients and consumers: 

Research transparency is essential for rigorous research. Systematic review (SR) authors should define when the outcomes are measured. If not pre-specified, it may introduce bias in selection of the reported result. We found the timing of outcome measurement is not usually defined despite the recommendation of the Cochrane Handbook. The finding may alert both researchers and readers of SRs, and may improve the research transparency among SRs.