| 1. |
- Ferro, Ana, et al.
(author)
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Alcohol intake and gastric cancer : Meta-analyses of published data versus individual participant data pooled analyses (StoP Project)
- 2018
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In: Cancer Epidemiology. - : ELSEVIER SCI LTD. - 1877-7821 .- 1877-783X. ; 54, s. 125-132
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Journal article (peer-reviewed)abstract
- Background: Individual participant data pooled analyses allow access to non-published data and statistical reanalyses based on more homogeneous criteria than meta-analyses based on systematic reviews. We quantified the impact of publication-related biases and heterogeneity in data analysis and presentation in summary estimates of the association between alcohol drinking and gastric cancer.Methods: We compared estimates obtained from conventional meta-analyses, using only data available in published reports from studies that take part in the Stomach Cancer Pooling (StoP) Project, with individual participant data pooled analyses including the same studies.Results: A total of 22 studies from the StoP Project assessed the relation between alcohol intake and gastric cancer, 19 had specific data for levels of consumption and 18 according to cancer location; published reports addressing these associations were available from 18, 5 and 5 studies, respectively. The summary odds ratios [OR, (95%CI)] estimate obtained with published data for drinkers vs. non-drinkers was 10% higher than the one obtained with individual StoP data [18 vs. 22 studies: 1.21 (1.07-1.36) vs. 1.10 (0.99-1.23)] and more heterogeneous (1(2): 63.6% vs 54.4%). In general, published data yielded less precise summary estimates (standard errors up to 2.6 times higher). Funnel plot analysis suggested publication bias.Conclusion: Meta-analyses of the association between alcohol drinking and gastric cancer tended to overestimate the magnitude of the effects, possibly due to publication bias. Additionally, individual participant data pooled analyses yielded more precise estimates for different levels of exposure or cancer subtypes.
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| 2. |
- Ferro, Ana, et al.
(author)
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Tobacco smoking and gastric cancer: : meta-analyses of published data versus pooled analyses of individual participant data (StoP Project).
- 2018
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In: European Journal of Cancer Prevention. - 0959-8278 .- 1473-5709. ; 27:3, s. 197-204
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Journal article (peer-reviewed)abstract
- Tobacco smoking is one of the main risk factors for gastric cancer, but the magnitude of the association estimated by conventional systematic reviews and meta-analyses might be inaccurate, due to heterogeneous reporting of data and publication bias. We aimed to quantify the combined impact of publication-related biases, and heterogeneity in data analysis or presentation, in the summary estimates obtained from conventional meta-analyses. We compared results from individual participant data pooled-analyses, including the studies in the Stomach Cancer Pooling (StoP) Project, with conventional meta-analyses carried out using only data available in previously published reports from the same studies. From the 23 studies in the StoP Project, 20 had published reports with information on smoking and gastric cancer, but only six had specific data for gastric cardia cancer and seven had data on the daily number of cigarettes smoked. Compared to the results obtained with the StoP database, conventional meta-analyses overvalued the relation between ever smoking (summary odds ratios ranging from 7% higher for all studies to 22% higher for the risk of gastric cardia cancer) and yielded less precise summary estimates (SE ≤2.4 times higher). Additionally, funnel plot asymmetry and corresponding hypotheses tests were suggestive of publication bias. Conventional meta-analyses and individual participant data pooled-analyses reached similar conclusions on the direction of the association between smoking and gastric cancer. However, published data tended to overestimate the magnitude of the effects, possibly due to publication biases and limited the analyses by different levels of exposure or cancer subtypes.
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| 3. |
- Salles-Filho, Sergio Luiz Monteiro, et al.
(author)
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Perspectives for the Brazilian bioethanol sector : The innovation driver
- 2017
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In: Energy Policy. - : Elsevier BV. - 0301-4215. ; 108, s. 70-77
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Journal article (peer-reviewed)abstract
- This article addresses the future of Brazil's bioethanol sector, focusing on its capabilities to innovate, its efforts toward producing cellulosic ethanol, and on recently implemented policies. Contrary to what has been argued in the literature, Brazil may not be prepared to face the technological and market challenges now emerging in the biofuels domain worldwide. Important productive investments were made by oil, energy, and chemical companies in bioethanol production in Brazil in the first decade of the 2000s; however, that sector has not shown levels of investment in innovation—either for first- or second-generation bioethanol—compatible with the challenges of making bioethanol a global commodity. Even considering recent policies in Brazil toward cellulosic bioethanol, the results achieved have been far from sustainable. This situation is partially due to uncertainties surrounding biofuels worldwide and partially due to contradictory policies toward liquid fuels in Brazil. The Brazilian government has simultaneously promoted both fossil fuels and renewables, thereby creating ambiguity among decision makers. These and other findings were drawn from an in-depth survey on innovation in the bioethanol sector in Brazil conducted in 2014 among 35 productive units affiliated to 58 industrial groups.
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