The relationship of study and authorship characteristics on trial sponsorship and self-reported conflicts of interest among neuro-oncology clinical trials

To examine the association between trial sponsorship sources, self-reported conflicts of interest (COI), and study and author characteristics in central nervous system (CNS) oncology clinical trials (CT). MEDLINE search was performed for original CT on "Central Nervous System Neoplasms"[Mesh]. The investigators assessed for relationships between funding source (industry, academic or cooperative, none, not described), COI (presented, none, or not reported), CT, and author characteristics. From 2010 to 2015, 319 CT were considered eligible. The majority of the studies involved primary gliomas (55.2%) and were Phase II CT (59.2%). Drug therapy was investigated in 83.0% of the CT. The remaining studies investigated surgery or radiotherapy. A minority of papers were published in journals with impact factor (IF) higher than > 10 (16%) or in regions other than North America and Europe (20.4%). Overall, 83.1% of studies disclosed funding sources: 32.6% from industry alone, 33.9% from an academic or cooperative group, and 10.7% from a mixed funding model. COI data was reported by 85.9% of trials, of which 56.2% reported no COI and 43.8% reported a related COI. Significant predictors for sponsorship (industry and/or academia) on univariate analysis were study design, type of intervention, journal impact factor, study conclusion, transparency of COI and presence of COI. On multivariate analysis, type of intervention, (P < 0.001), journal impact factor (IF) (P = 0.003), presence of COI (P < 0.001) and study conclusion (P = 0.003) remained significant predictors of sponsorship. For predicting COI, significant variables on univariate analysis were disease type, type of intervention, journal IF, funding source, and intervention arm being related to sponsor. On multivariate analysis, disease type (P = 0.003), journal IF (P < 0.001), type of intervention (P = 0.001), and funding source (P = 0.008) remained significant. The majority of CNS CT reported some external funding sources and non-related COI. We identified that drug trials, higher IF, presence of COI, and a neutral or negative study conclusion are associated with external funding. Likewise drug trials, higher IF, and glioma trials are associated with presence of COI.