Association between competing interests and authors' conclusions: epidemiological study of randomised clinical trials published in the BMJ

OBJECTIVE: To assess the association between competing interests and authors' conclusions in randomised clinical trials. DESIGN: Epidemiological study of randomised clinical trials published in the BMJ from January 1997 to June 2001. Financial competing interests were defined as funding by for profit organisations and other competing interests as personal, academic, or political. STUDIES: 159 trials from 12 medical specialties. MAIN OUTCOME MEASURES: Authors' conclusions defined as interpretation of extent to which overall results favoured experimental intervention. Conclusions appraised on 6 point scale; higher scores favour experimental intervention. RESULTS: Authors' conclusions were significantly more positive towards the experimental intervention in trials funded by for profit organisations alone compared with trials without competing interests (mean difference 0.48 (SE 0.13), P=0.014), trials funded by both for profit and non-profit organisations (0.30 (SE 0.10), P=0.003), and trials with other competing interests (0.45 (SE 0.13), P=0.006). Other competing interests and funding from both for profit and non-profit organisations were not significantly associated with authors' conclusions. The association between financial competing interests and authors' conclusions was not explained by methodological quality, statistical power, type of experimental intervention (pharmacological or non-pharmacological), type of control intervention (for example, placebo or active drug), or medical specialty. CONCLUSIONS: Authors' conclusions in randomised clinical trials significantly favoured experimental interventions if financial competing interests were declared. Other competing interests were not significantly associated with authors' conclusions.

研究目的：评估随机对照试验（randomised clinical trials）中利益冲突与作者结论之间的关联。
研究设计：针对1997年1月至2001年6月发表于《英国医学期刊》（BMJ）的随机对照试验开展的流行病学研究。其中，经济利益冲突定义为营利性组织资助，其他利益冲突则涵盖个人、学术或政治层面的利益冲突。
纳入研究：12个医学专科的159项试验。
主要结局指标：作者结论定义为对总体结果支持试验性干预的程度所作出的解读；结论采用6分制量表进行评价，得分越高表明越支持试验性干预。
研究结果：仅由营利性组织资助的试验中，作者对试验性干预的结论显著优于无利益冲突的试验（均数差0.48，标准误0.13，P=0.014），同时也优于同时接受营利性与非营利性组织资助的试验（0.30，标准误0.10，P=0.003），以及存在其他利益冲突的试验（0.45，标准误0.13，P=0.006）。其他利益冲突与同时接受营利性和非营利性组织资助的情况，与作者结论无显著关联。经济利益冲突与作者结论之间的关联，并未因方法学质量、统计效力、试验性干预类型（药物性或非药物性）、对照干预类型（如安慰剂或活性药物）或医学专科的不同而发生改变。
研究结论：若声明存在经济利益冲突，随机对照试验的作者结论会显著偏向试验性干预；其他类型的利益冲突与作者结论无显著关联。