Core Outcome Set for Research and Clinical Practice in Post COVID-19 Condition (Long COVID): An International Delphi Consensus Study ‘PC-COS’

Abstract

Background: Recent data suggest that many people experience Post COVID-19 Condition (Long COVID) following the acute phase of the SaRS CoV-2 infection. At present there is no agreement on what patient health outcomes should be measured in Post COVID-19 Condition. We aimed to identify core outcomes for Post COVID-19 Condition that stakeholders considered critical to assess in all research studies and clinical practice.

Methods: We conducted a multi-step study: (1) review of outcomes reported in studies of Post COVID-19 Condition to develop a list of potential core outcomes; (2) outcomes were then grouped, using the COMET taxonomy, to present in a consensus process; (3) a two-round online international modified Delphi consensus process, including 3 stakeholder groups (‘people with Post COVID-19 Condition and their carers’, ‘healthcare professionals and researchers’ and ‘healthcare professionals and researchers with Post COVID-19 Condition) to prioritise outcomes; and (4) an international online consensus meeting to finalize the core outcome set. Consensus ‘in’ was defined, a priori, as 80% or more of each stakeholder group rating an outcome as critical (‘7-9’ on a 9-point scale). Patient engagement and global outreach activities were undertaken at all stages of the project.

Findings: 1535 participants from 71 countries, representing six continents, were involved in the online modified Delphi process, with 1148 participating in both rounds (75% completion rate). Eleven of 24 outcomes met consensus ‘in’ criteria after the two Delphi rounds and consensus meeting: fatigue or exhaustion; pain; post-exertion symptoms; work/occupational and study changes; survival; and “functioning, symptoms and conditions” for each of the following outcomes: cardiovascular, respiratory, nervous system, cognition, mental and physical. ‘Recovery’ outcome was added ‘a-priori’ as a part of previously published COS on COVID-19.

Interpretation: This international study resulted in the development of a COS for Post COVID-19 Condition using a rigorous methodology. The generated consensus-based list of core outcomes should be assessed in clinical research and practice settings. The next step for the development of this COS will be to determine which measurement instruments best measure these outcomes.

Funding Information: Funding by the National Institute for Health Research (NIHR) (Grant COV-LT2-0072) supporting the second stage of the process.

Declaration of Interests: None to declare.

Ethics Approval Statement: Ethical approval for the study was given by the UK Health Research Authority and by the South West - Cornwall & Plymouth Research Ethics Committee (REC number 21/SW/0109).

Keywords: Covid-19, COVID-19 sequalae, Long COVID, Post-Acute Sequelae of SARS-CoV-2 infection, PASC, post-COVID-19 condition, outcomes, Core Outcome Set.