Duyx Bram, Urlings Miriam J E, Swaen Gerard M H, Bouter Lex M, Zeegers Maurice P
CAPHRI School for Public Health and Primary Care, Department of Genetics and Cell Biology, Maastricht University, Maastricht, Limburg, The Netherlands
CAPHRI School for Public Health and Primary Care, Department of Genetics and Cell Biology, Maastricht University, Maastricht, Limburg, The Netherlands.
BMJ Open. 2020 Oct 7;10(10):e033967. doi: 10.1136/bmjopen-2019-033967.
Epidemiological research on the association between diesel exhaust exposure and lung cancer risk has some methodological challenges that give rise to different conclusions and intense debates. This raises the question about the role of selective citation and of citation bias in particular. Our aim was to investigate the occurrence and prevalence of selective citation in this field.
Citation analysis.
Web of Science Core Collection.
We identified 96 publications in this network, with 4317 potential citations. For each publication, we extracted characteristics such as study conclusion and funding source. Some of these characteristics are related to the study content: study design, sample size, method of diesel exposure assessment, type of diesel technology under investigation, and whether smoking had been adjusted for.
Whether a citation occurs or not, measured and analysed according to the preregistered protocol. Exploratively we analysed the association between funding source and study conclusion.
Methodological content of a study was clearly related to citation, studies using more sophisticated methods were more likely to be cited. There was some evidence for citation bias: supportive publications had a higher chance of being cited than non-supportive ones, but after adjustment for study quality, this effect decreased substantially (adjusted OR 1.3, 95% CI 1.0 to 1.7). Explorative analyses indicated that three quarters of non-profit funded publications had a supportive study conclusion against only one quarter of the industry-funded publications.
There is evidence for selective citation within this field, but the evidence for citation bias was weak. It seems that factors related to the methodology had more impact on citation than the conclusion of a study. Interestingly, publications that were funded by industry were more skeptical about a causal relationship between diesel exhaust and lung cancer compared to non-profit-funded publications.
关于接触柴油尾气与肺癌风险之间关联的流行病学研究存在一些方法学挑战，这导致了不同的结论和激烈的争论。这就引发了关于选择性引用尤其是引用偏差作用的问题。我们的目的是调查该领域选择性引用的发生情况和流行程度。
引用分析。
科学网核心合集。
我们在该网络中识别出96篇出版物，有4317条潜在引用。对于每篇出版物，我们提取了研究结论和资金来源等特征。其中一些特征与研究内容相关：研究设计、样本量、柴油暴露评估方法、所研究的柴油技术类型以及是否对吸烟进行了调整。
根据预先注册的方案测量和分析引用是否发生。我们探索性地分析了资金来源与研究结论之间的关联。
研究的方法学内容与引用明显相关，使用更复杂方法的研究更有可能被引用。有一些证据表明存在引用偏差：支持性出版物被引用的可能性高于非支持性出版物，但在对研究质量进行调整后，这种效应大幅降低（调整后的比值比为1.3，95%置信区间为1.0至1.7）。探索性分析表明，四分之三由非营利资金资助的出版物有支持性的研究结论，而只有四分之一由行业资助的出版物有支持性结论。
有证据表明该领域存在选择性引用，但引用偏差的证据较弱。似乎与方法学相关的因素对引用的影响比研究结论更大。有趣的是，与非营利资金资助的出版物相比，行业资助的出版物对柴油尾气与肺癌之间的因果关系更为怀疑。
