Unplanned or unjustified subgroup or sensitivity analyses

This problem is addressed in PRISMA 2009, PRISMA 2020 and MECIR. Subgroup analyses should be pre-specified, kept to a minimum and represent potentially important clinical differences. Unplanned or unjustified combinations of different trials in meta-analyses represent a way of 'massaging the data'. This can also be thought of as 'p-hacking'.

Articles that support this problem:

Can Cochrane Reviews in controversial areas be biased? A sensitivity analysis based on the protocol of a Systematic Cochrane Review on low-level laser therapy in osteoarthritis

2005 : Photomedicine and laser therapy

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

2013 : Journal of clinical epidemiology

Attention should be given to multiplicity issues in systematic reviews

2008 : Journal of clinical epidemiology

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

2015 : Plos one

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

2011 : Plos one

Reporting quality of Cochrane systematic reviews with Chinese herbal medicines

2019 : Systematic reviews

Lessons learnt on transparency, scientific process and publication ethics. The short story of a long journey to get into the public domain unpublished data, methodological flaws and bias of the Cochrane HPV vaccines review

2019 : Bmj evidence-based medicine

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

2019 : Bmc medicine

Flaws in the application and interpretation of statistical analyses in systematic reviews of therapeutic interventions were common: a cross-sectional analysis

2018 : Journal of clinical epidemiology

Statistical heterogeneity in systematic reviews of clinical trials: a critical appraisal of guidelines and practice

2002 : Journal of health services research & policy

The Reporting Quality of Systematic Reviews in Japanese Physical Therapy Journals

2020 : Progress in rehabilitation medicine

The collaboration and reporting quality of social welfare systematic reviews in the Campbell Collaboration online library

2019 : Health & quality of life outcomes

The fate of urological systematic reviews registered in PROSPERO

2019 : World journal of urology

Is quality control of Cochrane reviews in controversial areas sufficient?

2006 : Journal of alternative & complementary medicine

Caution should be exercised when assessing ivermectin for the treatment of COVID-19 in systematic reviews

2022 : Reviews in medical virology

Saturated fat, the estimated absolute risk and certainty of risk for mortality and major cancer and cardiometabolic outcomes: an overview of systematic reviews

2023 : Systematic reviews