Multiplicity of outcomes and lack of pre-specification for outcome reporting

This problem is addressed in PRISMA 2009, PRISMA 2020, AMSTAR-2, ROBIS and MECIR. Sometimes changes to the primary outcome in a systematic review are made after knowledge of individual trials. The primary outcome for the systematic review should be prespecified and any amendments from the protocol to the main outcome of interest should be fully documented and justifed in the final report.

Articles that support this problem:

Selective reporting of outcomes in randomised controlled trials in systematic reviews of cystic fibrosis

2013 : Bmj open

Bias due to selective inclusion and reporting of outcomes and analyses in systematic reviews of randomised trials of healthcare interventions

2014 : The cochrane library

Outcome reporting bias in Cochrane systematic reviews: a cross-sectional analysis

2020 : Bmj open

Inadvertent P-hacking among trials and systematic reviews of the effect of progestogens in pregnancy? A systematic review and meta-analysis

2017 : Bjog: an international journal of obstetrics & gynaecology

Generalizability of findings from systematic reviews and meta-analyses in the Leading General Medical Journals

2020 : Journal of rehabilitation medicine

Many scenarios exist for selective inclusion and reporting of results in randomized trials and systematic reviews

2013 : Journal of clinical epidemiology

Multivariate meta-analysis helps examine the impact of outcome reporting bias in Cochrane rheumatoid arthritis reviews

2015 : Journal of clinical epidemiology

Methods to select results to include in meta-analyses deserve more consideration in systematic reviews

2015 : Journal of clinical epidemiology

Survey of new 2007 and 2011 Cochrane reviews found 37% of prespecified outcomes not reported

2015 : Journal of clinical epidemiology

Attention should be given to multiplicity issues in systematic reviews

2008 : Journal of clinical epidemiology

Dealing with effect size multiplicity in systematic reviews and meta‐analyses

2018 : Research synthesis methods

A third of systematic reviews changed or did not specify the primary outcome: a PROSPERO register study

2016 : Journal of clinical epidemiology

A systematic survey showed important limitations in the methods for assessing drug safety among systematic reviews

2020 : Journal of clinical epidemiology

The impact of outcome reporting bias in randomised controlled trials on a cohort of systematic reviews

2010 : Bmj

Multiplicity of data in trial reports and the reliability of meta-analyses: empirical study

2011 : Bmj

Outcomes in Cochrane systematic reviews related to wound care: An investigation into prespecification

2017 : Wound repair & regeneration

Identification and impact of outcome selection bias in meta‐analysis

2005 : Statistics in medicine

Registration of systematic reviews in PROSPERO: 30,000 records and counting

2018 : Systematic reviews

A meta-epidemiological study of subgroup analyses in cochrane systematic reviews of atrial fibrillation

2019 : Systematic reviews

Association between unreported outcomes and effect size estimates in Cochrane meta-analyses

2007 : Jama

Exploring treatment by covariate interactions using subgroup analysis and meta-regression in cochrane reviews: a review of recent practice

2015 : Plos one

Bias due to changes in specified outcomes during the systematic review process

2010 : Plos one

Outcomes in Cochrane systematic reviews addressing four common eye conditions: an evaluation of completeness and comparability

2014 : Plos one

Strong heterogeneity of outcome reporting in systematic reviews

2016 : Journal of clinical epidemiology

Inclusion criteria for outcomes of studies not clearly reported in Cochrane systematic reviews

2017 : Journal of clinical epidemiology

Discrepancies in outcome reporting exist between protocols and published oral health Cochrane systematic reviews

2015 : Plos one

Statistical multiplicity in systematic reviews of anaesthesia interventions: a quantification and comparison between Cochrane and non-Cochrane reviews

2011 : Plos one

Age-treatment subgroup analyses in Cochrane intervention reviews: a meta-epidemiological study

2019 : Bmc medicine

Clinical heterogeneity was a common problem in Cochrane reviews of physiotherapy and occupational therapy

2006 : Journal of clinical epidemiology

A descriptive analysis of child-relevant systematic reviews in the Cochrane Database of Systematic Reviews

2010 : Bmc pediatrics

Investigation of bias in meta-analyses due to selective inclusion of trial effect estimates: empirical study

2016 : Bmj open

The fate of urological systematic reviews registered in PROSPERO

2019 : World journal of urology

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

2018 : Plos biology

Epidemiology and Reporting Characteristics of Systematic Reviews of Biomedical Research: A Cross-Sectional Study

2016 : Plos medicine

Missing Data in Systematic Reviews and Meta-Analysis

2022 : Pediatric critical care medicine

Substantial heterogeneity found in reporting mortality in Cochrane systematic reviews and Core Outcome Sets in COMET database

2022 : Journal of clinical epidemiology