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Reporting Methods of Blinding in Randomized Trials Assessing Nonpharmacological Treatments
Open accessAbstract
BACKGROUND: Blinding is a cornerstone of treatment evaluation. Blinding is more difficult to obtain in trials assessing nonpharmacological treatment and frequently relies on "creative" (nonstandard) methods. The purpose of this study was to systematically describe the strategies used to obtain blinding in a sample of randomized controlled trials of nonpharmacological treatment. METHODS AND FINDINGS: We systematically searched in Medline and the Cochrane Methodology Register for randomized controlled trials (RCTs) assessing nonpharmacological treatment with blinding, published during 2004 in high-impact-factor journals. Data were extracted using a standardized extraction form. We identified 145 articles, with the method of blinding described in 123 of the reports. Methods of blinding of participants and/or health care providers and/or other caregivers concerned mainly use of sham procedures such as simulation of surgical procedures, similar attention-control interventions, or a placebo with a different mode of administration for rehabilitation or psychotherapy. Trials assessing devices reported various placebo interventions such as use of sham prosthesis, identical apparatus (e.g., identical but inactivated machine or use of activated machine with a barrier to block the treatment), or simulation of using a device. Blinding participants to the study hypothesis was also an important method of blinding. The methods reported for blinding outcome assessors relied mainly on centralized assessment of paraclinical examinations, clinical examinations (i.e., use of video, audiotape, photography), or adjudications of clinical events. CONCLUSIONS: This study classifies blinding methods and provides a detailed description of methods that could overcome some barriers of blinding in clinical trials assessing nonpharmacological treatment, and provides information for readers assessing the quality of results of such trials.
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“In manual therapy, blinding is an issue, as patients tend to be aware of the manual treatment and therapists cannot be blinded to the treatment intervention they deliver.37”
From Efficacy and safety of osteopathic manipulative treatment: an overview of systematic reviews (2022) · cites this paper as [37]
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“The most common method reported was avoiding unblinding by participants through asking them not to discuss their treatment, a method frequently reported in the existing literature [5, 14, 18, 23].”
From Blinding outcome assessors in randomised controlled trials of psychological interventions: how is it done? A narrative review (2026) · cites this paper as [5]
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“In particular, only one study (Epton et al., 2014) evidently concealed group allocation and, as is often the case in non-pharmacological trials (Boutron et al., 2007), none clearly ensured blinding of participants.”
From The effect of e-mental health interventions on academic performance in university and college students: A meta-analysis of randomized controlled trials (2020) · cites this paper as Boutron et al., 2007
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“methods have been proposed to mitigate these issues in trial design and quality assessment (Boutron et al., 2007”
From Systematic review and meta-analysis of interventions for depression and anxiety in persons with multiple sclerosis (2016) · cites this paper as Boutron et al., 2007
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“it is difficult to use a doubleblind design for patients in trials of psychotherapy”
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“which would affect the transitivity of the whole network and restricts the interpretation of these results.15”
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Cited by
Sorted by citations
SPIRIT 2013 explanation and elaboration: guidance for protocols of clinical trials
Chan, A.-W., Tetzlaff, J. M., Gotzsche, P. C., Altman, D. G., Mann, H., Berlin, J. A., Dickersin, K., Hrobjartsson, A., Schulz, K. F., Parulekar, W. R., et al. (2013) · BMJ · doi:10.1136/bmj.e7586 · Cited by 6,251
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Self-citationBoutron, I., Altman, D. G., Moher, D., Schulz, K. F., Ravaud, P., & for the CONSORT NPT Group* (2017) · Annals of Internal Medicine · doi:10.7326/m17-0046 · Cited by 1,538
Self-citationSmith, M., Hosking, J., Woodward, A. J., Witten, K., Macmillan, A. K., Field, A., Baas, P. H., & Mackie, H. W. (2017) · International Journal of Behavioral Nutrition and Physical Activity · doi:10.1186/s12966-017-0613-9 · Cited by 955
Boutron, I. (2010) · JAMA · doi:10.1001/jama.2010.651 · Cited by 842
Self-citation
Metadata
- Authors
- Boutron, I., Guittet, L., Estellat, C., Moher, D., Hróbjartsson, A., & Ravaud, P.
- Affiliations
- Inserm (FR)
- University of Ottawa (CA)
- Rigshospitalet (DK)
- Corresponding author
- Boutron, Isabelle
- ORCID
- Venue
- PLoS Medicine
- Publisher
- Public Library of Science (PLoS)
- Published
- 2007-02-20
- Volume
- 4
- Issue
- 2
- Pages
- e61
- ISSN
- 1549-1277 (ISSN-L)
- 1549-1676
- PMC
- PMC1800311
- OpenAlex
- W2118789584
- Cited by
- 389
- References
- 55
- Citations by year
- 2026: 34 · 2025: 27 · 2024: 14 · 2023: 21 · 2022: 20 · 2021: 27 · 2020: 27 · 2019: 24 · 2018: 36 · 2017: 17 · 2016: 16 · 2015: 24 · 2014: 20 · 2013: 20 · 2012: 18
- FWCI
- 10.56
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Locations
- PLoS Medicine (publishedVersion, cc-by)
- Europe PMC (PubMed Central) (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- HAL (submittedVersion, other-oa)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Figshare (submittedVersion, cc-by)
- Funders
- University of Ottawa
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Life Sciences › Neuroscience › Cognitive Neuroscience › Pain Management and Placebo Effect
- Keywords
- blinding, randomization, non-pharmacological treatment, sham procedure, placebo, rehabilitation, psychotherapy, trial reporting quality
- MeSH terms
- Double-Blind Method, Humans, Research Design, Randomized Controlled Trials as Topic
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