Relation of study quality, concordance, take home message, funding, and impact in studies of influenza vaccines: Systematic review

Cochrane Vaccines Field, ASL (Azienda Sanitaria Locale) AL 20, 15100 Alessandria, Italy.
BMJ (online) (Impact Factor: 17.45). 02/2009; 338(feb12 2):b354. DOI: 10.1136/bmj.b354
Source: PubMed


To explore the relation between study concordance, take home message, funding, and dissemination of comparative studies assessing the effects of influenza vaccines.
Systematic review without meta-analysis.
Search of the Cochrane Library, PubMed, Embase, and the web, without language restriction, for any studies comparing the effects of influenza vaccines against placebo or no intervention. Abstraction and assessment of quality of methods were carried out.
We identified 259 primary studies (274 datasets). Higher quality studies were significantly more likely to show concordance between data presented and conclusions (odds ratio 16.35, 95% confidence interval 4.24 to 63.04) and less likely to favour effectiveness of vaccines (0.04, 0.02 to 0.09). Government funded studies were less likely to have conclusions favouring the vaccines (0.45, 0.26 to 0.90). A higher mean journal impact factor was associated with complete or partial industry funding compared with government or private funding and no funding (differences between means 5.04). Study size was not associated with concordance, content of take home message, funding, and study quality. Higher citation index factor was associated with partial or complete industry funding. This was sensitive to the exclusion from the analysis of studies with undeclared funding.
Publication in prestigious journals is associated with partial or total industry funding, and this association is not explained by study quality or size.

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    • "Distorted reporting in abstracts is of particular concern as these sections are easily accessed (and freely available), so clinical decisions may be based on abstracts alone [24]. Even when the full report is available, readers may only scan the abstract and conclusions [12,25]. These issues are of particular relevance in wound care, an area of healthcare where many of the treatment decisions are made by nurses working in community settings, where there are significant time constraints and limited access to computers and research findings. "
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    • "Vaccination did not have a statistically significant effect on hospitalization or complications, and no evidence was found that vaccines prevent viral transmission. As the review included industry funded trials, the authors found it necessary to include a warning as to the interpretation of its content, stressing that the association between industry funding and study conclusions and publication, as demonstrated in a systematic review of studies on the effect of influenza vaccines [8], could have biased their results and that reliable evidence on influenza vaccines is thin but there is evidence of widespread manipulation of conclusions and spurious notoriety of the studies. The reviewers suggest that although serious harm from vaccination may be rare it cannot be ignored and conclude that the results of their literature review discourage the utilization of vaccination against influenza in healthy adults as a routine measure. "
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    • "In a survey of faculty at top U.S. medical research institutions, Tereskerz et al. (2009) found over two-thirds of researchers (338 out of 506) received some support from industry. Studies show that the financial interests of researchers are positively associated with outcomes favorable to the sponsor in medical studies (Friedman and Richter, 2004; Jefferson et al., 2009; Yank et al., 2007). Not only individual researchers, but also research institutions can be influenced by industry sponsorships such as grants, endowed chairs, and other gifts (Tereskerz, 2003). "
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