Language bias in randomised controlled trials published in English and German

Egger, Matthias; Zellweger-Zähner, Tanja; Schneider, Martin; Junker, Christoph; Lengeler, Christian; Antes, Gerd

doi:10.1016/s0140-6736(97)02419-7

Cited by 909 publications

(529 citation statements)

References 26 publications

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“…The language selection could favour positive studies, following the assumption that they are more often published in English, whereas the negative ones tend to be published more often in local journals using the author's native languages (Egger et al, 1997). However, we did not identify many papers published in a national language (Italian, Russian, Serbian, German) (Lelle, 1990;Topic et al, 2002;Kushlinskii et al, 2004;Costarelli et al, 2005).…”

Section: Discussionmentioning

confidence: 95%

Ki-67 as prognostic marker in early breast cancer: a meta-analysis of published studies involving 12 155 patients

et al. 2007

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The Ki-67 antigen is used to evaluate the proliferative activity of breast cancer (BC); however, Ki-67's role as a prognostic marker in BC is still undefined. In order to better define the prognostic value of Ki-67/MIB-1, we performed a meta-analysis of studies that evaluated the impact of Ki-67/MIB-1 on disease-free survival (DFS) and/or on overall survival (OS) in early BC. Sixty-eight studies were identified and 46 studies including 12 155 patients were evaluable for our meta-analysis; 38 studies were evaluable for the aggregation of results for DFS, and 35 studies for OS. Patients were considered to present positive tumours for the expression of Ki-67/MIB-1 according to the cut-off points defined by the authors. Ki-67/MIB-1 positivity is associated with higher probability of relapse in all patients (HR ¼ 1.93 (95% confidence interval (CI): 1.74 -2.14); Po0.001), in node-negative patients (HR ¼ 2.31 (95% CI: 1.83 -2.92); Po0.001) and in node-positive patients (HR ¼ 1.59 (95% CI: 1.35 -1.87); Po0.001). Furthermore, Ki-67/MIB-1 positivity is associated with worse survival in all patients (HR ¼ 1.95 (95% CI: 1.70 -2.24; Po0.001)), node-negative patients (HR ¼ 2.54 (95% CI: 1.65 -3.91); Po0.001) and node-positive patients (HR ¼ 2.33 (95% CI: 1.83 -2.95); Po0.001). Our meta-analysis suggests that Ki-67/ MIB-1 positivity confers a higher risk of relapse and a worse survival in patients with early BC.

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Section: Discussionmentioning

confidence: 95%

Ki-67 as prognostic marker in early breast cancer: a meta-analysis of published studies involving 12 155 patients

et al. 2007

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“…This selection could favour the positive studies that are more often published in English while the negative ones tend to be more often published in native languages (Egger et al, 1997). Moreover, our review took into account only fully published studies.…”

Section: Discussionmentioning

confidence: 99%

Ki-67 expression and patients survival in lung cancer: systematic review of the literature with meta-analysis

et al. 2004

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Among new biological markers that could become useful prognostic factors for lung carcinoma, Ki-67 is a nuclear protein involved in cell proliferation regulation. Some studies have suggested an association between Ki-67 and poor survival in lung cancer patients. In order to clarify this point, we have performed a systematic review of the literature, using the methodology already described by our Group, the European Lung Cancer Working Party. In total, 37 studies, including 3983 patients, were found to be eligible. In total, 49% of the patients were considered as having a tumour positive for the expression of Ki-67 according to the authors cutoff. In all, 29 of the studies dealt with non-small-cell lung carcinoma (NSCLC), one with small-cell carcinoma (SCLC), two with carcinoid tumours and five with any histology. In terms of survival results, Ki-67 was a bad prognosis factor for survival in 15 studies while it was not in 22. As there was no statistical difference in quality scores between the significant and nonsignificant studies evaluable for the meta-analysis, we were allowed to aggregate the survival results. The combined hazard ratio for NSCLC, calculated using a random-effects model was 1.56 (95% CI: 1.30 -1.87), showing a worse survival when Ki-67 expression is increased. In conclusion, our meta-analysis shows that the expression of Ki-67 is a factor of poor prognosis for survival in NSCLC.

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“…This was not feasible given the large literature base, nor was it possible to systematically check for duplicates of patients across papers. We did not include foreign language papers because of the difficulties in translation, and this may have introduced bias if statistically or clinically significant studies were more likely to be (re)written for publication in an English language journal (20).…”

Section: Discussionmentioning

confidence: 99%

A Systematic Review of Molecular and Biological Tumor Markers in Neuroblastoma

Riley¹,

Heney

Jones³

et al. 2004

Clinical Cancer Research

180

110

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Purpose: The aim of this study was to conduct a systematic review, and where possible meta-analyses, of molecular and biological tumor markers described in neuroblastoma, and to establish an evidence-based perspective on their clinical value for the screening, diagnosis, prognosis, and monitoring of patients.Experimental Design: A well-defined, reproducible search strategy was used to identify the relevant literature from 1966 to February 2000.Results: A total of 428 papers studying the use of 195 different tumor markers in neuroblastoma were identified. Small sample sizes, poor statistical reporting, large heterogeneity across studies (e.g., in cutoff levels), and publication bias limited meta-analysis to the area of prognosis only; MYCN, chromosome 1p, DNA index, vanillylmandelic acid: homovanillic acid ratio, CD44, Trk-A, neuron-specific enolase, lactate dehydrogenase, ferritin, and multidrug resistance were all identified as potentially important prognostic tools.Conclusions: This systematic review forms a knowledge base of the tumor markers studied thus far in neuroblastoma, and has identified some of the most important prognostic markers, which should be considered in future research and treatment strategies. Importantly, the review has also highlighted some general problems across primary tumor marker studies, in particular poor and heterogeneous reporting. These need to be addressed to allow better clinical interpretation and enable more appropriate evidence-based reviews in the future. In particular, collaboration of cancer research groups is needed to enable bigger sample sizes, standardize methods of analysis and reporting, and facilitate the pooling of individual patient data.

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Language bias in randomised controlled trials published in English and German

Cited by 909 publications

References 26 publications

Ki-67 as prognostic marker in early breast cancer: a meta-analysis of published studies involving 12 155 patients

Ki-67 as prognostic marker in early breast cancer: a meta-analysis of published studies involving 12 155 patients

Ki-67 expression and patients survival in lung cancer: systematic review of the literature with meta-analysis

A Systematic Review of Molecular and Biological Tumor Markers in Neuroblastoma

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