Data extraction errors and double counting

This problem is addressed in ROBIS and MECIR. Data extraction for outcomes in individual studies should be performed carefully and independently verified in order to ensure accuracy. Double counting can occur when multiple included papers report data from the same trials.

Articles that support this problem:

A case study of binary outcome data extraction across three systematic reviews of hip arthroplasty: errors and differences of selection

2013 : Bmc research notes

High prevalence but low impact of data extraction and reporting errors were found in Cochrane systematic reviews

2005 : Journal of clinical epidemiology

Data extraction methods: an analysis of internal reporting discrepancies in single manuscripts and practical advice

2020 : Journal of clinical epidemiology

Errors in systematic reviews: an example of computed tomography screening for lung cancer

2014 : European journal of cancer prevention

Errors in the conduct of systematic reviews of pharmacological interventions for irritable bowel syndrome

2010 : American journal of gastroenterology

Different patterns of duplicate publication: an analysis of articles used in systematic reviews

2004 : Jama

Incorrect inclusion of individual studies and methodological flaws in systematic review and meta-analysis

2014 : British journal of general practice

Missing binary data extraction challenges from Cochrane reviews in mental health and Campbell reviews with implications for empirical research

2017 : Research synthesis methods

Cochrane has not consistently followed the COPE guidelines

2020 : European journal of clinical investigation

Increased risks for random errors are common in outcomes graded as high certainty of evidence

2019 : Journal of clinical epidemiology

Selecting studies (not reports) as the unit of interest of systematic reviews and meta-analyses: an essential practice

2020 : International journal of obesity

Disagreements in meta-analyses using outcomes measured on continuous or rating scales: observer agreement study

2009 : Bmj

Letter to the Editor concerning "The role of non-rigid cervical collar in pain relief and functional restoration after whiplash injury: a systematic review and a pooled analysis of randomized controlled trials" by Ricciardi L, et al. (Eur Spine J; [2019] 28:1821-1828)

2020 : European spine journal

Appraising the exercise oncology literature: a reminder of the rigour needed in systematic reviews

2019 : British journal of sports medicine

Validity of data extraction in evidence synthesis practice of adverse events: reproducibility study

2022 : Bmj

RE: Physical Activity and the Risk of Liver Cancer: A Systematic Review and Meta-Analysis of Prospective Studies and a Bias Analysis

2020 : Journal of the national cancer institute

Importance of excluded duplicates reporting in a systematic review

2021 : World journal of pediatrics

Errors and Biases in Meta-analysis of the Prevalence of Olfactory Dysfunction in Patients With COVID-19

2021 : Otolaryngology - head and neck surgery (united states)

Methodological considerations for systematic review and meta-analysis of Xpert bladder cancer monitor

2022 : Urologic oncology: seminars and original investigations

Letter to the editor regarding "The effectiveness of manual therapy on pain, physical function, and nerve conduction studies in carpal tunnel syndrome patients: a systematic review and meta-analysis"

2022 : International orthopaedics