Contacting of authors modified crucial outcomes of systematic reviews but was poorly reported, not systematic, and produced conflicting results

Ref ID 593
First Author R. Meursinge Reynders
Journal JOURNAL OF CLINICAL EPIDEMIOLOGY
Year Of Publishing 2019
URL https://www.jclinepi.com/article/S0895-4356(19)30456-1/fulltext
Keywords • General medical
• Cochrane
• Author
• Missing data
Problem(s) • Failure to address missing outcome data in analyses
Article Type Empirical
Article Subtype Survey/questionnaire of authors opinions/practices
First Author Country The Netherlands
Aim To assess the prevalence, reporting quality and need of contacting study authors by Cochrane reviewers to obtain additional information for all new Cochrane intervention reviews published between January 1, 2016 and January 31, 2017
Level of Investigation Descriptive
Summary of Findings Cochrane reviewers contacted (73.4%) or had tried to contact authors (80.0%) frequently but reporting by Cochrane reviewers on procedures for contacting authors and their outcomes was poor. Most eligible studies in the reviews were poorly reported, but few reviewers 21.2% (65/306) reported that they had contacted these studies.
Number of systematic reviews included 319
Number of eligible systematic reviews assessed 846
Treatment impacted Yes
Treatment impacted description The survey identified changes in key outcomes of reviews as a consequence of contacting of authors for: (1) the risk of bias scores, (2) the GRADE scores, (3) the summary primary or secondary outcomes, and (4) the summary effect size of the primary outcome
Interpretation impacted Yes
Interpretation impacted description The prevalence of reviews in which the summary effect size of the primary outcome was modified as a result of the information obtained from the contacted studies was 24.6% ((15/61) 95% CI: 14.5% - 37.3%)