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Communications to the Editor |

Locating and Selecting Appraisal Studies for Reviews FREE TO VIEW

Hugo Hyung Bok Yoo; Thais Thomas Queluz
Author and Funding Information

Affiliations: Botucatu Medical School, Botucatu, Brazil,  University of Pennsylvania Medical Center, Philadelphia, PA

Correspondence to: Hugo Hyung Bok Yoo, MD, PhD, Department of Internal Medicine, Botucatu Medical School-UNESP, Botucatu, SP 18618-000, Brazil; e-mail: hugo@fmb.unesp.br



Chest. 2004;125(2):798-799. doi:10.1378/chest.125.2.798
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Published online

To the Editor:

We have read with great interest the critical care review by Kreider and Lipson (July 2003)1 concerning bronchoscopy for atelectasis in the ICU. However, the authors used a single method of locating review articles, including only MEDLINE, and excluded other electronic databases. Currently, such a restricted search is generally not considered adequate. Studies2 have shown that only 30 to 80% of all known published randomized, controlled trials were identifiable using MEDLINE (depending on the area or specific question). A comprehensive search is important not only for ensuring that as many studies as possible are identified, but also to minimize any selection bias for those that are found. Relying exclusively on a MEDLINE search may retrieve a set of reports unrepresentative of all reports that would have been identified through a comprehensive search of several sources.3 To prevent bias and to ensure that all relevant data are included in a review, it is fundamental to use multiple sources such as EMBASE, Best Evidence, and the Cochrane Library to identify studies and then to use a systematic approach5 to select those that will be included.

Another electronic database is LILACS5 for Latin America and the Caribbean, which indexes regional literature that contains 270,244 (40th edition, May 2001) citations of literature published since 1982 and abstracts in English, Portuguese, and Spanish. The US National Library of Medicine medical subject headings (MeSH) vocabulary is used to index each LILACS citation. LILACS is edited by BIREME (Latin-American and Caribbean Health Science Information Center), an agency of the Pan American Health Organization/World Health Organization, located in São Paulo City, Brazil. Of the 670 journals indexed in LILACS, only 45 overlap with those indexed in MEDLINE.56

Searching in LILACS according to the strategy proposed by the Cochrane Collaboration5 of the same terms (bronchoscopy, atelectasis, ICU, and critical illness) used by Kreider and Lipson1 for randomized, controlled trials, allowed the retrieval of two other citations.6 They may or may not reinforce the conclusions reached by authors, but our point is to stress that any search strategy of systematic or narrative reviews can and should include LILACS as an obligatory database.

References

Kreider, ME, Lipson, DA (2003) Bronchoscopy for atelectasis in the ICU: a case report and review of the literature.Chest124,344-350. [CrossRef] [PubMed]
 
Dickersin, K, Scherer, R, Lefebvre, C Identifying relevant studies for systematic reviews.BMJ1994;309,1286-1291. [CrossRef] [PubMed]
 
Juni, P, Holenstein, F, Sterne, J, et al Direction and impact of language bias in meta-analyses of controlled trials: empirical study.Int J Epidemiol2002;31,115-123. [CrossRef] [PubMed]
 
Mulrow, CD Oxman, AD eds. Locating and selecting studies. In: Cochrane collaboration handbook (updated December 9, 1996), Section 5. The Cochrane Collaboration, Issue 1. 1997; Update Software. Oxford, UK:.
 
Centro Latino-Americano e do Caribe de Informações em Ciências da Saúde. Periódicos Latino-Americanos: características formais e procedimentos para avaliação de trabalhos. São Paulo, Brazil: BIREME, 1996. Available at: http://www.bireme.br. Accessed January 8, 2004.
 
Castro, AA, Clark, OAC, Atallah, AN Optimal search strategy for clinical trials in the Latin American and Caribbean health science literature database (LILACS).Rev Paul Med1997;115,1423-1426
 
To the Editor:

We appreciate the comments made by Drs. Yoo and Queluz. We agree with the importance of using multiple sources to identify appropriate studies when performing any systematic review or meta-analysis. In our review,1 we performed an extensive search using MEDLINE utilizing two different search engines (OVID and PubMed). Additionally, we identified other citations from careful review of relevant bibliographies of both original studies and appropriate review articles. In light of the concern of Drs. Yoo and Queluz, we again performed our search using the Cochrane and the EMBASE databases. We identified only one potential additional reference in a journal of limited circulation. We believe it is unlikely we missed any study that would have significantly altered our final conclusions.

Drs. Yoo and Queluz bring up an important issue regarding language bias in the conduct of systematic reviews. It is currently unclear how non-English–language studies differ from those published in English. There are conflicting reports regarding differences in quality and the likelihood of publication of negative results in non-English–language literature.24 Despite these concerns, evidence suggests that excluding trials published in languages other than English generally has little impact on the final conclusions of review articles and meta-analyses.2 Specifically, Moher et al5 conclude that there is “… no evidence that language restricted meta-analyses lead to biased estimates of intervention effectiveness.” By including non-English–language articles and increasing the number of examined studies, the general direction and scope of estimates will not change; however, the precision of estimates is likely to be increased. If there had been adequate studies to perform a meta-analysis and determine a single estimate of the effectiveness of bronchoscopy for atelectasis in the ICU, inclusion of non-English–language articles may have been beneficial. However, the final conclusions of our review would not have been altered.

References
Kreider, ME, Lipson, DA Bronchoscopy for atelectasis in the ICU: a case report and review of the literature.Chest2003;124,344-350. [CrossRef] [PubMed]
 
Juni, P, Holenstein, F, Sterne, J, et al Direction and impact of language bias in meta-analyses of controlled trials: empirical study.Int J Epidemiol2002;31,115-123. [CrossRef] [PubMed]
 
Egger, M, Zellweger-Zahner, T, Schneider, M, et al Language bias in randomised controlled trials published in English and German.Lancet1997;350,326-329. [CrossRef] [PubMed]
 
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.Lancet1996;347,363-366. [CrossRef] [PubMed]
 
Moher, D, Pham, B, Klassen, TP, et al What contributions do languages other than English make on the results of meta-analyses?J Clin Epidemiol2000;53,964-972. [CrossRef] [PubMed]
 

Figures

Tables

References

Kreider, ME, Lipson, DA (2003) Bronchoscopy for atelectasis in the ICU: a case report and review of the literature.Chest124,344-350. [CrossRef] [PubMed]
 
Dickersin, K, Scherer, R, Lefebvre, C Identifying relevant studies for systematic reviews.BMJ1994;309,1286-1291. [CrossRef] [PubMed]
 
Juni, P, Holenstein, F, Sterne, J, et al Direction and impact of language bias in meta-analyses of controlled trials: empirical study.Int J Epidemiol2002;31,115-123. [CrossRef] [PubMed]
 
Mulrow, CD Oxman, AD eds. Locating and selecting studies. In: Cochrane collaboration handbook (updated December 9, 1996), Section 5. The Cochrane Collaboration, Issue 1. 1997; Update Software. Oxford, UK:.
 
Centro Latino-Americano e do Caribe de Informações em Ciências da Saúde. Periódicos Latino-Americanos: características formais e procedimentos para avaliação de trabalhos. São Paulo, Brazil: BIREME, 1996. Available at: http://www.bireme.br. Accessed January 8, 2004.
 
Castro, AA, Clark, OAC, Atallah, AN Optimal search strategy for clinical trials in the Latin American and Caribbean health science literature database (LILACS).Rev Paul Med1997;115,1423-1426
 
Kreider, ME, Lipson, DA Bronchoscopy for atelectasis in the ICU: a case report and review of the literature.Chest2003;124,344-350. [CrossRef] [PubMed]
 
Juni, P, Holenstein, F, Sterne, J, et al Direction and impact of language bias in meta-analyses of controlled trials: empirical study.Int J Epidemiol2002;31,115-123. [CrossRef] [PubMed]
 
Egger, M, Zellweger-Zahner, T, Schneider, M, et al Language bias in randomised controlled trials published in English and German.Lancet1997;350,326-329. [CrossRef] [PubMed]
 
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.Lancet1996;347,363-366. [CrossRef] [PubMed]
 
Moher, D, Pham, B, Klassen, TP, et al What contributions do languages other than English make on the results of meta-analyses?J Clin Epidemiol2000;53,964-972. [CrossRef] [PubMed]
 
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