Conflicts of interest in randomised controlled surgical trials: systematic review and qualitative and quantitative analysis

Conflicts of interest may lead to biased trial designs and unbalanced interpretation of study results. We aimed to evaluate the reporting of potential conflicts of interest in full publications of surgical randomised controlled trials (RCTs). A systematic literature search was performed in CENTRAL, MEDLINE and EMBASE (1985–2014) to find all surgical RCTs of medical devices and perioperative pharmacological or nutritional interventions. The information on conflicts of interest was evaluated both quantitatively and qualitatively, and the development of stated conflicts over time was studied. Of 7934 articles, 444 met the inclusion criteria. In 93 of 444 trials (20.9%), conflicts of interest were disclosed. In half of the cases, the information provided was insufficient to permit conclusions regarding possible influence on the trials. Information about conflicts of interest has increased continuously during the last decades (1985–1994: 0%, 1995–2004: 2.8% and 2005–2014: 33.0%; p<0.001). Among the 115 industry-funded trials, industry participation was considered as a potential conflict of interest in 24 cases (20.9%). Over the past three decades, only every 10th trial has provided appropriate information on conflicts of interest. However, transparency is crucial for the reliability of evidence-based medicine. There is an urgent need for the full disclosure of all conflicts of interest in surgical publishing and for transparency regarding cooperation between academia and industry.