Bias in clinical intervention research.

Gluud, Lise Lotte

doi:10.1093/aje/kwj069

Cited by 636Meta-analysis and systematic reviewsStatistical Methods in Clinical TrialsPharmaceutical industry and healthcare

Bias in clinical intervention research.

Gluud, Lise Lotte·2006·American Journal of Epidemiology

DOI 10.1093/aje/kwj069

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Abstract

Research on bias in clinical trials may help identify some of the reasons why investigators sometimes reach the wrong conclusions about intervention effects. Several quality components for the assessment of bias control have been suggested, but although they seem intrinsically valid, empirical evidence is needed to evaluate their effects on the extent and direction of bias. This narrative review summarizes the findings of methodological studies on the influence of bias in clinical trials. A number of methodological studies suggest that lack of adequate randomization in published trial reports may be associated with more positive estimates of intervention effects. The influence of double-blinding and follow-up is less clear. Several studies have found a significant association between funding sources and pro-industry conclusions. However, the methodological studies also show that bias is difficult to detect and appraise. The extent of bias in individual trials is unpredictable. A-priori exclusion of trials with certain characteristics is not recommended. Appraising bias control in individual trials is necessary to avoid making incorrect conclusions about intervention effects.

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The likelihood that the treatment effect reported in a systematic review approximates the truth depends on the validity of the included studies, as certain methodological characteristics may be associated with effect sizes.
“The likelihood that the treatment effect reported in a systematic review approximates the truth depends on the validity of the included studies, as certain methodological characteristics may be associated with effect sizes [87],[88].”
From The PRISMA Statement for Reporting Systematic Reviews and Meta-Analyses of Studies That Evaluate Health Care Interventions: Explanation and Elaboration (2009) · cites this paper as [87]

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Authors: Gluud, L. L.
Affiliations: Rigshospitalet (DK)
Corresponding author: Gluud, Lise Lotte
ORCID: Gluud, Lise Lotte
Venue: American Journal of Epidemiology
Publisher: Oxford University Press (OUP)
Published: 2006-01-27
Volume: 163
Issue: 6
Pages: 493-501
ISSN: 0002-9262 (ISSN-L)
1476-6256
DOI: 10.1093/aje/kwj069
OpenAlex: W2127765911
Cited by: 636
References: 138
Citations by year: 2026: 6 · 2025: 32 · 2024: 12 · 2023: 44 · 2022: 15 · 2021: 29 · 2020: 33 · 2019: 40 · 2018: 25 · 2017: 35 · 2016: 24 · 2015: 23 · 2014: 34 · 2013: 40 · 2012: 41
FWCI: 12.71
Type: journal article
Language: en
Open access: closed
Locations: American Journal of Epidemiology (publishedVersion)
PubMed (publishedVersion)
Topics: Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Pharmacology › Pharmaceutical industry and healthcare
Keywords: bias in clinical trials, bias control, double blinding, follow-up, funding sources, industry funding, publication bias, bias assessment, trial quality, intervention effects
MeSH terms: Humans, Research Support as Topic, Selection Bias, Odds Ratio, Randomized Controlled Trials as Topic, Publication Bias, Sample Size, Evidence-Based Medicine

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