SynthesisBMC medical research methodology2005
Methodological bias in cluster randomised trials.
Synthesis in BMC medical research methodology, 2005. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to 2 registered trials, which are not on this map. Cited by 112 papers, 31 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.
A Pragmatic Cluster Randomized Controlled Trial of a Multi-element Psychosocial Intervention for Early Psychosis in a 10 Million Inhabitant Catchment Area Aimed to Measure the Treatment's Feasibility and Effectiveness: GET UP-PIANO Trial
Cross-Cultural Adaptation of a Betel Quid Cessation Program and Evaluation of Its Effectiveness in a Malaysian High-Risk Community
Who cites it
112 citing papers in PubMed, 31 syntheses or guidelines pooled it, 311 citations in OpenAlex.
- Interventions for preventing falls in older people in hospitals.The Cochrane database of systematic reviews · 2026Pooled it
- Interventions for preventing falls in older people in care facilities.The Cochrane database of systematic reviews · 2025Pooled it
- Interventions for postburn pruritus.The Cochrane database of systematic reviews · 2024Pooled it
- Pooled it
- Collaborative care approaches for people with severe mental illness.The Cochrane database of systematic reviews · 2024Pooled it
- Psychosocial interventions for reducing antipsychotic medication in care home residents.The Cochrane database of systematic reviews · 2023Pooled it
- Do cash transfers alleviate common mental disorders in low- and middle-income countries? A systematic review and meta-analysis.PloS one · 2023Pooled it
- Dressings and topical agents for the management of open wounds after surgical treatment for sacrococcygeal pilonidal sinus.The Cochrane database of systematic reviews · 2022Pooled it
- Effects of a gluten-reduced or gluten-free diet for the primary prevention of cardiovascular disease.The Cochrane database of systematic reviews · 2022Pooled it
- Patient and lay carer education for preventing pressure ulceration in at-risk populations.The Cochrane database of systematic reviews · 2021Pooled it
- Intervention effect estimates in cluster randomized versus individually randomized trials: a meta-epidemiological study.International journal of epidemiology · 2019Pooled it
- Risk assessment tools for the prevention of pressure ulcers.The Cochrane database of systematic reviews · 2019Pooled it
- Organisation of health services for preventing and treating pressure ulcers.The Cochrane database of systematic reviews · 2018Pooled it
- Interventions for preventing falls in older people in care facilities and hospitals.The Cochrane database of systematic reviews · 2018Pooled it
- Tobacco cessation interventions for young people.The Cochrane database of systematic reviews · 2017Pooled it
- Antiseptics for burns.The Cochrane database of systematic reviews · 2017Pooled it
- Antibiotics and antiseptics for pressure ulcers.The Cochrane database of systematic reviews · 2016Pooled it
- Antibiotics and antiseptics for surgical wounds healing by secondary intention.The Cochrane database of systematic reviews · 2016Pooled it
- A 'test and treat' strategy for elevated wound protease activity for healing in venous leg ulcers.The Cochrane database of systematic reviews · 2016Pooled it
- Prenatal education for congenital toxoplasmosis.The Cochrane database of systematic reviews · 2015Pooled it
52 more citing papers are in PubMed but not listed here.
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 at 1 institution in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundCluster randomised trials can be susceptible to a range of methodological problems. These problems are not commonly recognised by many researchers. In this paper we discuss the issues that can lead to bias in cluster trials.
methodsWe used a sample of cluster randomised trials from a recent review and from a systematic review of hip protectors. We compared the mean age of participants between intervention groups in a sample of 'good' cluster trials with a sample of potentially biased trials. We also compared the effect sizes, in a funnel plot, between hip protector trials that used individual randomisation compared with those that used cluster randomisation.
resultsThere is a tendency for cluster trials, with evidence methodological biases, to also show an age imbalance between treatment groups. In a funnel plot we show that all cluster trials show a large positive effect of hip protectors whilst individually randomised trials show a range of positive and negative effects, suggesting that cluster trials may be producing a biased estimate of effect.
conclusionMethodological biases in the design and execution of cluster randomised trials is frequent. Some of these biases associated with the use of cluster designs can be avoided through careful attention to the design of cluster trials. Firstly, if possible, individual allocation should be used. Secondly, if cluster allocation is required, then ideally participants should be identified before random allocation of the clusters. Third, if prior identification is not possible, then an independent recruiter should be used to recruit participants.
Indexed as
Identifiers
What OpenQuestion holds
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.