SynthesisBMC medical research methodology2016
The matching quality of experimental and control interventions in blinded pharmacological randomised clinical trials: a methodological systematic review.
Synthesis in BMC medical research methodology, 2016. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 10 papers, 4 of them syntheses that pooled it.
What it found
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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
10 citing papers in PubMed, 4 syntheses or guidelines pooled it.
- Impact of active placebo controls on estimated drug effects in randomised trials: a systematic review of trials with both active placebo and standard placebo.The Cochrane database of systematic reviews · 2023Pooled it
- Attempting to Separate Placebo Effects from Exercise in Chronic Pain: A Systematic Review and Meta-analysis.Sports medicine (Auckland, N.Z.) · 2022Pooled it
- Low Reporting of Cointerventions in Recent Cardiovascular Clinical Trials: A Systematic Review.Journal of the American Heart Association · 2020Pooled it
- Inadequate description of placebo and sham controls in a systematic review of recent trials.European journal of clinical investigation · 2019Pooled it
- Scoping review on the genotoxicity of silver nanoparticles in endodontics: therapeutic saviors or genetic saboteurs?Odontology · 2025Article
- Acceptability of a 250 mg levofloxacin formulation in children receiving TB preventive treatment.IJTLD open · 2025Article
- 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
- Intense bitterness of molecules: Machine learning for expediting drug discovery.Computational and structural biotechnology journal · 2021Article
- TIDieR-Placebo: A guide and checklist for reporting placebo and sham controls.PLoS medicine · 2020Article
- How placebo characteristics can influence estimates of intervention effects in trials.CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne · 2018Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
4 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundBlinding is a pivotal method to avoid bias in randomised clinical trials. In blinded drug trials, experimental and control interventions are often designed to be matched, i.e. to appear indistinguishable. It is unknown how often matching procedures are inadequate, so we decided to systematically identify and analyse studies of matching quality in drug trials. Our primary objective was to assess the proportion of studies that concluded that the matching was inadequate; our secondary objective was to describe mechanisms for inadequate matching.
methodsSystematic review. We searched PubMed, Google Scholar and Web of Science Citation Index for studies that assessed whether supposedly indistinguishable interventions (experimental and control) in randomized clinical drug trials could be distinguished based on physical properties (e.g. appearance or smell). Two persons decided on study eligibility and extracted data independently. Our primary analysis was based on the conclusions of each study. In supportive analyses, we defined a low and a high threshold for inadequate matching. We summarised results qualitatively.
resultsWe included studies of 36 trials, of which 28 (78%) were published before 1977. The studies differed considerably with regard to design, methodology and analysis. Sixteen of the 36 studies (44%) concluded inadequate matching. When we adapted high or low thresholds for inadequate matching, the number of trials with inadequate matching was reduced to 12 (33%) or increased to 26 (72%). Inadequate matching was concluded in 7 of 22 trials (32%) based on a defined cohort of trials. Inadequate matching was concluded in 9 of 14 trials (64%) which were not based on a trial cohort, and therefore at a higher risk of publication bias. The proportion of inadequate matching did not seem to depend on publication year. Typical mechanisms of inadequate matching were differences in taste or colour.
conclusionWe identified matching quality studies of 36 randomized clinical drug trials. Sixteen of the 36 studies (44%) concluded inadequate matching. Few studies of matching quality in contemporary trials have been published, but show similar results as found for older trials. Inadequate matching in drug trials may be more prevalent than commonly believed.
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