PO247 Dissemination bias in clinical trials of neurodegenerative diseases: an observational study

Objective To investigate the characteristics associated with trial discontinuation and non-publication in four major neurodegenerative diseases. Methods We searched ClinicalTrials.gov for all randomised, interventional, phase II-IV trials that were registered between 1 st January 2000 and 31 st December 2009 and included adults with Alzheimer’s disease, multiple sclerosis, Parkinson’s disease, or motor neurone disease. We identified publications from these trials by extensive online searching and contact with authors. Results We identified 362 eligible trials, of which 12% (42/362) were discontinued. 28% (91/320) of completed trials remained unpublished after five years. Trial discontinuation was independently associated with number of patients (p=0.015; more likely in trials with ≤100 patients) and phase of trial (p=0.009; more likely in phase IV trials). Trial non-publication was independently associated with blinding status (p=0.005; more likely in single-blind trials), number of centres (p=0.010; more likely in single-centre trials), phase of trial (p=0.041; more likely in phase II trials), and sponsor category (p=0.001; more likely in industry-sponsored trials). Conclusions We found evidence of dissemination bias in randomised trials of interventions for neurodegenerative diseases. Associations with trial discontinuation and non-publication were similar to findings in other diseases.