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THE EFFECT OF ENGLISH-LANGUAGE RESTRICTION ON SYSTEMATIC REVIEW-BASED META-ANALYSES: A SYSTEMATIC REVIEW OF EMPIRICAL STUDIES

Published online by Cambridge University Press:  26 April 2012

Andra Morrison ,
Julie Polisena ,
Don Husereau ,
Kristen Moulton ,
Michelle Clark ,
Michelle Fiander ,
Monika Mierzwinski-Urban ,
Tammy Clifford ,
Brian Hutton  and
Danielle Rabb
Andra Morrison
Affiliation:
Canadian Agency for Drugs and Technologies in Health
Julie Polisena
Affiliation:
Canadian Agency for Drugs and Technologies in Health email: [email protected]
Don Husereau
Affiliation:
Private Universität für Gesundheitswissenschaften, Medizinische Informatik und Technik GmbH University of Ottawa
Kristen Moulton
Affiliation:
Canadian Agency for Drugs and Technologies in Health
Michelle Clark
Affiliation:
Canadian Agency for Drugs and Technologies in Health
Michelle Fiander
Affiliation:
Cochrane Effective Practice and Organization of Care (EPOC) Group
Monika Mierzwinski-Urban
Affiliation:
Canadian Agency for Drugs and Technologies in Health
Tammy Clifford
Affiliation:
Canadian Agency for Drugs and Technologies in Health and University of Ottawa
Brian Hutton
Affiliation:
Ottawa Hospital Research Institute
Danielle Rabb
Affiliation:
Canadian Agency for Drugs and Technologies in Health
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Abstract

Objectives: The English language is generally perceived to be the universal language of science. However, the exclusive reliance on English-language studies may not represent all of the evidence. Excluding languages other than English (LOE) may introduce a language bias and lead to erroneous conclusions.

Study Design and Setting: We conducted a comprehensive literature search using bibliographic databases and grey literature sources. Studies were eligible for inclusion if they measured the effect of excluding randomized controlled trials (RCTs) reported in LOE from systematic review-based meta-analyses (SR/MA) for one or more outcomes.

Results: None of the included studies found major differences between summary treatment effects in English-language restricted meta-analyses and LOE-inclusive meta-analyses. Findings differed about the methodological and reporting quality of trials reported in LOE. The precision of pooled estimates improved with the inclusion of LOE trials.

Conclusions: Overall, we found no evidence of a systematic bias from the use of language restrictions in systematic review-based meta-analyses in conventional medicine. Further research is needed to determine the impact of language restriction on systematic reviews in particular fields of medicine.

Keywords

Language biasMethodologyMeta-analysesConventional medicine
Type
METHODS
Information
International Journal of Technology Assessment in Health Care , Volume 28 , Issue 2 , April 2012 , pp. 138 - 144
Copyright
Copyright © Cambridge University Press 2012

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References

REFERENCES

1.Centre for Reviews and Dissemination. Systematic reviews: CRD's guidance for undertaking reviews in health care. York, UK: Centre for Reviews and Dissemination, University of York; 2009.Google Scholar
2.Deeks, JJ, Higgins, JPT, Altman, DG. Identifying and measuring heterogeneity. In: Higgins, JPT, Green, S, eds. Cochrane handbook for systematic reviews of interventions Version 5.1.0. Oxford: The Cochrane Collaboration; 2011.Google Scholar
3.Downs, SH, Black, N. The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J Epidemiol Community Health. 1998;52:377–384.CrossRefGoogle ScholarPubMed
4.Egger, M, Juni, P, Bartlett, C, Holenstein, F, Sterne, J. How important are comprehensive literature searches and the assessment of trial quality in systematic reviews? Empirical study. Health Technol Assess. 2003;7:1–76.CrossRefGoogle ScholarPubMed
5.Egger, M, Zellweger-Zähner, T, Schneider, M, et al. Language bias in randomised controlled trials published in English and German. Lancet. 1997;350:326–329.CrossRefGoogle ScholarPubMed
6.Fung IC-H. Seek, and ye shall find: Accessing the global epidemiological literature in different languages. Emerg Themes Epidemiol. 2008;5:21.CrossRefGoogle Scholar
7.Grégorie, G, Derderian, F, Le Lorier, J. Selecting the language of the publications included in a meta-analysis: Is there a tower of Babel bias? J Clin Epidemiol. 1995;48:159–163.CrossRefGoogle Scholar
8.Higgins, JPT, Green, S, eds. Cochrane handbook for systematic reviews of interventions. Version 5.1.0 ed. Oxford (UK): The Cochrane Collaboration; 2011.Google Scholar
9.Hottest journals of the millennium (so far). Sci Watch. 2005;16.Google Scholar
10.Jadad, AR, Moore, RA, Carroll, D, et al. Assessing the quality of reports of randomized clinical trials: Is blinding necessary? Control Clin Trials 1996;17:1–12.CrossRefGoogle ScholarPubMed
11.Jüni, P, Holenstein, F, Sterne, J, Bartlett, C, Egger, M. Direction and impact of language bias in meta-analyses of controlled trials: Empirical study. Int J Epidemiol. 2002;31:115–123.CrossRefGoogle ScholarPubMed
12.Moher, D, Pham, B, Lawson, ML, Klassen, TP. The inclusion of reports of randomised trials published in languages other than English in systematic reviews. Health Technol Assess. 2003;7:iii-90.CrossRefGoogle ScholarPubMed
13.Moher, D, Fortin, P, Jadad, AR, et al. Completeness of reporting of trials published in languages other than English: Implications for conduct and reporting of systematic reviews. Lancet. 1996 February 10;347:363–366.CrossRefGoogle ScholarPubMed
14.Moher, D, Pham, B, Jones, A, et al. Does quality of reports of randomised trials affect estimates of intervention efficacy reported in meta-analyses? Lancet. 1998;352:609–613.CrossRefGoogle ScholarPubMed
15.Moher, D, Pham, B, Klassen, TP, et al. What contributions do languages other than English make on the results of meta-analyses? J Clin Epidemiol. 2000;53:964–972.CrossRefGoogle ScholarPubMed
16.Morrison, A, Moulton, K, Clark, M, et al. English-language restriction when conducting systematic review-based metaanalyses: Systematic review of published studies. Ottawa: Canadian Agency for Drugs and Technologies in Health; 2009.Google Scholar
17.National Cancer Institute. Conventional medicine. Dictionary of cancer terms. Bethesda, MD: National Institutes of Health; 2007.Google Scholar
18.Pan, Z, Trikalinos, TA, Kavvoura, FK, Lau, J, Ioannidis, JPA. Local literature bias in genetic epidemiology: An empirical evaluation of the Chinese literature. Plos Med. 2005;2:1309–1317.CrossRefGoogle ScholarPubMed
19.Pham, B, Klassen, TP, Lawson, ML, Moher, D. Language of publication restrictions in systematic reviews gave different results depending on whether the intervention was conventional or complementary. J Clin Epidemiol. 2005;58:769–776.CrossRefGoogle ScholarPubMed
20.Wilkin, T, Gillies, R, Davies, K. EMBASE versus MEDLINE for family medicine searches. Can MEDLINE searches find the forest or a tree? Can Fam Physician. 2005;51:849–850.Google Scholar