We would like to thank M. Miravitlles and co-workers for their interest in our meta-analysis 1. They commented on our choice not to include randomised controlled trials (RCTs) in the meta-analysis that were written in languages other than English, French, German or Italian. In addition, they criticised the fact that the references of the excluded RCTs were not available. We welcome the letter by our respectable colleagues and would like to respond to the points they raised.
We would like to emphasise that our research team's policy regarding the reporting of meta-analyses is to provide the references of all excluded trials to secure transparency and reproducibility of our work. For instance, in another meta-analysis performed by our team that has been recently published in the European Respiratory Journal (ERJ), we have done so 2. However, for the contribution under discussion, we would have to have provided 139 additional references (i.e. the number of the studies that were omitted for various reasons as explained in the relevant figure of our article); we considered that this number was probably excessive, given the space limitations of the ERJ.
We carefully reviewed the abstracts of the five RCTs that were excluded due to language restrictions 3–7. None of them provided data relevant to the subject of our meta-analysis (namely the comparison of macrolides, quinolones and amoxicillin/clavulanate for the treatment of patients with acute bacterial exacerbations of chronic bronchitis). Thus, the findings of our meta-analysis would not be different if we did not use language restrictions.
We would also like to point out that a considerable proportion of meta-analyses that are published in high-impact factor journals include only English language studies. In addition, in the Quality Of Reporting Of Meta-analyses (QUOROM) statement, language-inclusive meta-analyses are encouraged, but restriction in study selection based on the language of publication is not considered unacceptable. Besides, a recent comprehensive study on the topic revealed that “for conventional medicine interventions, language-restricted systematic reviews, compared with language-inclusive ones, did not introduce biased results, in terms of estimates of intervention effectiveness” and concluded that “language restrictions do not change the results of conventional medicine systematic reviews” 8. Apparently, the Editors of the ERJ have been aware of this evidence and, given the clinical importance of our meta-analysis, decided to publish it after the appropriate peer review.
Nevertheless, we certainly share the reasonable concerns of our colleagues regarding the penetration of the English language in modern research. In fact, we are very sensitive regarding this issue as well and, moreover, we have already commented on it 9. In addition, we have also compiled a list of a number of non-English language world databases of summaries of articles in the biomedical fields with the hope that such databases might contain data useful for researchers and clinicians 10.
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