An international survey indicated that unpublished systematic reviews exist

Ref ID 602
First Author A. C. Tricco
Journal JOURNAL OF CLINICAL EPIDEMIOLOGY
Year Of Publishing 2009
URL https://www.jclinepi.com/article/S0895-4356(08)00271-0/fulltext
Keywords Protocols
Publication bias
General medical
Problem(s) Unpublished or "zombie" reviews (the file-drawer effect)
Number of systematic reviews included 625
Summary of Findings Respondents reported a total of 199 unpublished systematic reviews. Reasons for not publishing included lack of time, lack of funding or organizational support, manuscript being rejected or operational issues.
Did the article find that the problem(s) led to qualitative changes in interpretation of the results? Not Applicable
Are the methods of the article described in enough detail to replicate the study? Yes