Cited by 269Ethics in Clinical ResearchStatistical Methods in EpidemiologyEthics and bioethics in healthcare

Written informed consent and selection bias in observational studies using medical records: systematic review

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Kho, M. E, Duffett, M., Willison, D. J, Cook, D. J, Brouwers, M. C·2009·BMJ

Abstract

OBJECTIVES: To determine whether informed consent introduces selection bias in prospective observational studies using data from medical records, and consent rates for such studies. DESIGN: Systematic review. DATA SOURCES: Embase, Medline, and the Cochrane Library up to March 2008, reference lists from pertinent articles, and searches of electronic citations. STUDY SELECTION: Prospective observational studies reporting characteristics of participants and non-participants approached for informed consent to use their medical records. Studies were selected independently in duplicate; a third reviewer resolved disagreements. DATA EXTRACTION: Age, sex, race, education, income, or health status of participants and non-participants, the participation rate in each study, and susceptibility of these calculations to threats of selection and reporting bias. RESULTS: Of 1650 citations 17 unique studies met inclusion criteria and had analysable data. Across all outcomes there were differences between participants and non-participants; however, there was a lack of consistency in the direction and the magnitude of effect. Of 161 604 eligible patients, 66.9% consented to use of data from their medical records. CONCLUSIONS: Significant differences between participants and non-participants may threaten the validity of results from observational studies that require consent for use of data from medical records. To ensure that legislation on privacy does not unduly bias observational studies using medical records, thoughtful decision making by research ethics boards on the need for mandatory consent is necessary.

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  • The prospective 6-month study reported here showed similar results to 3-month data presented previously and similar glycemic control to a retrospective cohort using Bigfoot Unity.

    “In general, the prospective 6-month study reported here showed similar results to 3-month data presented previously (35) and similar glycemic control to a retrospective cohort using Bigfoot Unity (34); here, the baseline HbA1c was higher (9.1% vs 8.4%), which may reflect health status or other demographic biases in those who consent to participate in an ongoing study vs those who do not (36).”

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Authors
Kho, M. E., Duffett, M., Willison, D. J., Cook, D. J., & Brouwers, M. C.
Affiliations
  • McMaster University (CA)
  • McMaster Children's Hospital (CA)
  • Cancer Care Ontario (CA)
Corresponding author
Kho, M. E
Venue
BMJ
Publisher
BMJ
Published
2009-03-12
Volume
338
Issue
mar12 2
Pages
b866-b866
ISSN
  • 0007-1447 (ISSN-L)
  • 0959-8138
  • 1468-5833
OpenAlex
W2022496558
Cited by
269
References
22
Citations by year
2026: 12 · 2025: 15 · 2024: 23 · 2023: 22 · 2022: 9 · 2021: 12 · 2020: 15 · 2019: 24 · 2018: 16 · 2017: 9 · 2016: 12 · 2015: 25 · 2014: 11 · 2013: 19 · 2012: 15
FWCI
2.03
Type
journal article
Language
en
Open access
Licence
cc-by-nc
Locations
  • BMJ (publishedVersion, cc-by-nc)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
Funders
Canadian Institutes of Health Research
Topics
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Ethics in Clinical Research
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Ethics and bioethics in healthcare
Keywords
written informed consent, selection bias, medical records, consent rates, research ethics committees, reporting bias
MeSH terms
Humans, Informed Consent, Medical Records, Research Design, Selection Bias

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