The Core Outcome measures in Squamous Intraepithelial precursor lesions of the Anus (COrSIcA) study: A protocol for the development of a core outcome set for future anal high-grade squamous intraepithelial lesion (aHSIL) treatment trials

Introduction There are multiple treatments for anal high-grade squamous intraepithelial lesion (aHSIL). The evidence for aHSIL treatments is scarce and of poor quality, such that the optimal approach cannot be defined. Existing trials in aHSIL have used different ways of measuring the effects of treatment. This makes comparing the results of trials very difficult. Trials are also likely to have been poor at reporting treatment effects important to patients. Treatment trials are needed to determine optimal approaches. Key to the quality of these trials is consistent and meaningful outcome measurement and reporting. Methods and Analysis The Core Outcome measures in Squamous Intraepithelial precursor lesions of the Anus (COrSIcA) study aims to develop a core outcome set (COS) for use in future late-phase aHSIL treatment trials. This is a standardised set of outcomes deemed most important by key stakeholders, which should be measured and reported in all future treatment trials for the condition. Systematic review of current treatment studies, and interviews with patients who have lived experience of aHSIL, will determine a longlist of potentially important outcomes. Consensus methods (an international Delphi survey and consensus meeting), taking into account the views of key stakeholders (patients, healthcare professionals and clinician trialists) with experience of the condition, will determine which outcomes from the longlist are most important and subsequently be included in the COS. Ethics and Dissemination Utilisation of the COS in future treatment trials will ensure outcomes reported are consistent and meaningful. NHS/HRA research ethics committee approval has been granted. The study is registered with the Core Outcome Measures in Effectiveness Trials (COMET) initiative and is listed in their database (Study ID 2511, https://www.comet-initiative.org/Studies/Details/2511).