The CONSENSUS study: protocol for a mixed methods study to establish which outcomes should be included in a core outcome set for oropharyngeal cancer

Background: The incidence of oropharyngeal cancer is increasing in the developed world. This has led to a large rise in research activity and clinical trials in this area, yet there is no consensus on which outcomes should be measured. As a result, the outcomes measured often differ between trials of comparable interventions, making the combination or comparison of results between trials impossible. Outcomes may also be 'cherry-picked', such that favourable results are reported, and less favourable results withheld. The development of a minimum outcome reporting standard, known as a core outcome set, goes some way to addressing these problems. Core outcome sets are ideally developed using a patient-centred approach so that the outcomes measured are relevant to patients and clinical practice. Core outcome sets drive up the quality and relevance of research by ensuring that the right outcomes are consistently measured and reported in trials in specific areas of health or healthcare. Methods/Design: This is a mixed methods study involving three phases to develop a core outcome set for oropharyngeal cancer clinical trials. Firstly, a systematic review will establish which outcomes are measured in published oropharyngeal cancer randomised controlled trials (RCTs). Secondly, qualitative interviews with patients and carers in the UK and the USA will aim to establish which outcomes are important to these stakeholders. Data from these first two stages will be used to develop a comprehensive list of outcomes to be considered for inclusion in the core outcome set. In the third stage, patients and clinicians will participate in an iterative consensus exercise known as a Delphi study to refine the contents of the core outcome set. This protocol lays out the methodology to be implemented in the CONSENSUS study. Discussion: A core outcome set defines a minimum outcome reporting standard for clinical trials in a particular area of health or healthcare. Its consistent implementation in oropharyngeal cancer clinical trials will improve the quality and relevance of research.