SynthesisClinical trials (London, England)2021
Blinding, sham, and treatment effects in randomized controlled trials for back pain in 2000-2019: A review and meta-analytic approach.
Synthesis in Clinical trials (London, England), 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 18 papers, 2 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
18 citing papers in PubMed, 2 syntheses or guidelines pooled it, 47 citations in OpenAlex.
- The blinding status and characteristics in acupuncture clinical trials: a systematic reviews and meta-analysis.Systematic reviews · 2024Pooled it
- Interventions for preventing back pain among office workers - a systematic review and network meta-analysis.Scandinavian journal of work, environment & health · 2023Pooled it
- Successful Blinding or Wishful Thinking? A Secondary Analysis of a Randomised Controlled Trial of Manual Therapy.European journal of pain (London, England) · 2026Trial
- Evaluation of 3D-Printed Models in Dentoalveolar Trauma Simulation: A Randomized Trial in Undergraduate Dental Training.Dental traumatology : official publication of International Association for Dental Traumatology · 2025Trial
- 'Which treatment do you believe you received?' A randomised blinding feasibility trial of spinal manual therapy.Chiropractic & manual therapies · 2025Trial
- Seeing Through the Blind: Belief About Treatment Randomization and Smoking Cessation Outcome Among People With Current or Past Major Depressive Disorder Who Smoke in a Placebo-Controlled Trial of Varenicline.Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco · 2024Trial
- Is blinding in studies of manual soft tissue mobilisation of the back possible? A feasibility randomised controlled trial with Swiss graduate students.Chiropractic & manual therapies · 2024Trial
- A randomised, pragmatic clinical trial of ACUpuncture plus standard care versus standard care alone FOr Chemotherapy Induced peripheral Neuropathy (ACUFOCIN).European journal of oncology nursing : the official journal of European Oncology Nursing Society · 2022Trial
- Effect of Partial vs Full Disclosure of Potential Assignment to Placebo on Participant Blinding, Perceptions of Group Assignment, and Trial Outcomes: A Randomized Clinical Trial.JAMA network open · 2022Trial
- Unmasking three blinding indices for randomized controlled trials: comparison and application.Contemporary clinical trials communications · 2025Article
- Waiting for pain: effect of a mindfulness intervention during a wait situation on pain intensity.Frontiers in pain research (Lausanne, Switzerland) · 2025Article
- Seeing the Truth About Double Blinding.Journal of general internal medicine · 2024Review
- Participant's treatment guesses and adverse events in back pain trials: Nocebo in action?Clinical trials (London, England) · 2024Article
- Drug trials are more likely to disclose full placebo control information than non-drug trials: A cross-sectional study of participant information leaflets of placebo-controlled trials.Integrative medicine research · 2024Article
- Feasibility of blinding spinal manual therapy interventions among participants and outcome assessors: protocol for a blinding feasibility trial.Pilot and feasibility studies · 2024Article
- Meta-epidemiologic review: blinding and sham treatment in clinical trial design for osteopathic manipulative treatment research.International journal of osteopathic medicine : IJOM · 2024Article
- The Biology of Placebo and Nocebo Effects on Experimental and Chronic Pain: State of the Art.Journal of clinical medicine · 2023Review
- Blinding Assessment: One Step Forward.Dental hypothesesArticle
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
8 authors at 7 institutions in 2 countries.
Funding
Abstract
backgroundBlinding aims to minimize biases from what participants and investigators know or believe. Randomized controlled trials, despite being the gold standard to evaluate treatment effect, do not generally assess the success of blinding. We investigated the extent of blinding in back pain trials and the associations between participant guesses and treatment effects.
methodsWe did a review with PubMed/OvidMedline, 2000-2019. Eligibility criteria were back pain trials with data available on treatment effect and participants' guess of treatment. For blinding, blinding index was used as chance-corrected measure of excessive correct guess (0 for random guess). For treatment effects, within- or between-arm effect sizes were used. Analyses of investigators' guess/blinding or by treatment modality were performed exploratorily.
resultsForty trials (3899 participants) were included. Active and sham treatment groups had mean blinding index of 0.26 (95% confidence interval: 0.12, 0.41) and 0.01 (-0.11, 0.14), respectively, meaning 26% of participants in active treatment believed they received active treatment, whereas only 1% in sham believed they received sham treatment, beyond chance, that is, random guess. A greater belief of receiving active treatment was associated with a larger within-arm effect size in both arms, and ideal blinding (namely, "random guess," and "wishful thinking" that signifies both groups believing they received active treatment) showed smaller effect sizes, with correlation of effect size and summary blinding indexes of 0.35 (
conclusionParticipants in active treatments in back pain trials guessed treatment identity more correctly, while those in sham treatments tended to display successful blinding. Excessive correct guesses (that could reflect weaker blinding and/or noticeable effects) by participants and investigators demonstrated larger effect sizes. Blinding and sham treatment effects on back pain need due consideration in individual trials and meta-analyses.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.