Unpublished or "zombie" reviews (the file-drawer effect)

Articles that support this problem:

Factors predicting completion and time to publication of Cochrane reviews

2009 : Open medicine

Reporting bias in the literature on the associations of health-related behaviors and statins with cardiovascular disease and all-cause mortality

2018 : Plos biology

The fate of urological systematic reviews registered in PROSPERO

2019 : World journal of urology

Unpublished systematic reviews and financial support: a meta-epidemiological study

2017 : Bmc research notes

Cochrane systematic reviews for the mental health field: is the gold standard tarnished?

2013 : Psychiatric services

Following 411 Cochrane protocols to completion: a retrospective cohort study

2008 : Plos one

An international survey indicated that unpublished systematic reviews exist

2009 : Journal of clinical epidemiology

Deficiencies in the publication and reporting of the results of systematic reviews presented at scientific medical conferences

2015 : Journal of clinical epidemiology

Half of systematic reviews about pain registered in PROSPERO were not published and the majority had inaccurate status

2019 : Journal of clinical epidemiology

More systematic reviews were registered in PROSPERO each year, but few records’ status was up-to-date

2020 : Journal of clinical epidemiology

Following Cochrane review protocols to completion 10 years later: a retrospective cohort study and author survey

2019 : Journal of clinical epidemiology

Zombie reviews taking over the PROSPERO systematic review registry. It’s time to fight back!

2019 : British journal of sports medicine

Characteristics, completion and publication of PROSPERO records in regional anesthesia for acute perioperative pain

2023 : Journal of comparative effectiveness research