Developing a Core Outcome Set and Identifying outcome measurement instruments to measure COS for use in clinical practice and research in Human T-Cell Lymphotropic Virus Type-1

Background: Human T-Cell Lymphotropic Virus Type-1 (HTLV-1), a rare retroviral infection, can result in neurological complications (HTLV Associated Myelopathy) or blood cancer.

Key UK risk factors include African or Afro-Caribbean ethnicity, being born in or to parents from endemic countries, and having an HTLV-1-positive partner. Approximately 82.5 million people worldwide are living with HTLV-1.

The incidence in England and Wales has risen sharply to around 36,000 cases in 2021, influenced by migration and a higher prevalence among those identifying as Black/Black African/Afro-Caribbean. I work in the UK's centre to support people with this disease. Current measures in HTLV clinical care and research focus on factors such as viral load.

This does not accurately correlate with disease progression and lacks patient relevance.

A core outcome set(COS) is a consensus-based standardised collection of outcomes used in clinical practice and research.

Establishing a COS for HTLV-1 is essential for promoting consistency and enhancing the quality of information on disease progression and intervention effects.

Aim: To develop a Core Outcome Set and identify outcome measurement instruments for the COS, to use in HTLV-1 clinical practice and research.

Research Questions Which outcomes need to be measured in those living with HTLV Associated Myelopathy(HAM) and HTLV-1 Asymptomatic carriers(ACs)? Which existing measurement instruments are best to measure these core outcomes?

Objectives: Identify what to measure: Work Package 1 Identify and refine a list of outcome domains for those living with HAM and ACs.

Prioritise and reach a consensus regarding these domains from the perspective of those living with HAM and ACs, clinicians and researchers Identify how to measure: Work Package 2 Determine which existing measures could be used for each domain Evaluate and appraise the existing measures available for each domain Reach a consensus on the most appropriate existing measure for each domain of the COS Methods: An iterative mixed-methods study employing both qualitative and quantitative methods will be used.

I will use the Core Outcome Measures in Effectiveness Trials (COMET) framework to guide the development of this COS.

I will create the study protocol following Core-Outcome-Set-STAndardised Protocol-Items and Core-Outcome-Set-STAndards-for-Development guidelines for COS development.

Inclusion criteria for all work packages: HTLV-1-Associated-Myelopathy and HTLV-1-Asymptomatic carriers; significant others of those with HAM and specialist clinicians and researchers working with people with HTLV-1. Objective 1(WP1): A rapid review identifying outcomes used in HTLV clinical practice and research studies.

Focus groups and semi-structured interviews with stakeholders to identify their outcomes of interest.

The resulting long list of outcomes will be refined and used in a multi-stakeholder 2 round-modified Delphi survey where the outcomes will be scored for importance. Consensus criteria have been set and the core outcome set will be agreed in a multi-stakeholder consensus meeting. Objective 2(WP2): Identify and psychometrically review existing outcome measurement instruments.

Finally, a consensus meeting will determine the selection of one measure for each identified outcome domain.

Anticipated impacts: Patient empowerment through strong PPIE, increased awareness and engagement with those living with HTLV-1 and guidelines for a standardised approach to data collection that enhances care quality.