The DOI matches its Crossref record; 21 of the 22 references it cites were found in a registry or an index.
Written informed consent and selection bias in observational studies using medical records: systematic review
Open accessAbstract
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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“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).”
From Observed Glycemic and Psychosocial Benefits in the Prospective Bigfoot Unity Real World Study: A 6-Month Analysis (2025) · cites this paper as [36]
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Mining electronic health records: towards better research applications and clinical care
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Increasing value and reducing waste in biomedical research regulation and management
Salman, R. A., Beller, E., Kagan, J., Hemminki, E., Phillips, R. S., Savulescu, J., Macleod, M. R., Wisely, J., & Chalmers, I. (2014) · The Lancet · doi:10.1016/s0140-6736(13)62297-7 · Cited by 552
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Ethical aspects of registry-based research in the Nordic countries
Ludvigsson, J. F., Nørgaard, M., Weiderpass, E., Håberg, S. E., Lafolie, P., Sarkkola, C., von Kraemer, S., Zoëga, H., & Knudsen, G. P. (2015) · Clinical Epidemiology · doi:10.2147/clep.s90589 · Cited by 368
Metadata
- 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
- PMC
- PMC2769263
- 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
- hybrid
- doi.org
- 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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