A core outcome set for post-COVID-19 condition in adults for use in clinical practice and research: an international Delphi consensus study

Health consequences that persist beyond the acute infection phase of COVID-19, termed post-COVID-19 condition (also commonly known as long COVID), vary widely and represent a growing global health challenge. Research on post-COVID-19 condition is expanding but, at present, no agreement exists on the health outcomes that should be measured in people living with the condition. To address this gap, we conducted an international consensus study, which included a comprehensive literature review and classification of outcomes for post-COVID-19 condition that informed a two-round online modified Delphi process followed by an online consensus meeting to finalise the core outcome set (COS). 1535 participants from 71 countries were involved, with 1148 individuals participating in both Delphi rounds. Eleven outcomes achieved consensus for inclusion in the final COS: fatigue; pain; post-exertion symptoms; work or occupational and study changes; survival; and functioning, symptoms, and conditions for each of cardiovascular, respiratory, nervous system, cognitive, mental health, and physical outcomes. Recovery was included a priori because it was a relevant outcome that was part of a previously published COS on COVID-19. The next step in this COS development exercise will be to establish the instruments that are most appropriate to measure these core outcomes. This international consensus-based COS should provide a framework for standardised assessment of adults with post-COVID-19 condition, aimed at facilitating clinical care and research worldwide.


To provide a framework for standardised assessment of adults with post-COVID-19 condition, aimed at facilitating clinical care and research worldwide


Daniel Munblit, Timothy Nicholson, Athena Akrami, Christian Apfelbacher, Jessica Chen, Wouter De Groote, Janet V Diaz, Sarah L Gorst, Nicola Harman, Alisa Kokorina, Piero Olliaro, Callum Parr, Jacobus Preller, Nicoline Schiess, Jochen Schmitt, Nina Seylanova, Frances Simpson, Allison Tong, Dale M Needham, Paula R Williamson, and the PC-COS project steering committee


Journal: Lancet respiratory medicine
Volume: 10
Issue: 7
Pages: 715 - 724
Year: 2022
DOI: 10.1016/S2213-2600(22)00169-2

Further Study Information

Current Stage: Completed
Funding source(s): There was no funding for the first stage of the Post-COVID-19 Condition Core Outcome Set (PC-COS) study; the second stage of the PC-COS study is funded by the UK National Institute for Health and Care Research (NIHR; grant COV-LT2-0072).

Health Area

Disease Category: Infectious disease

Disease Name: Post-Covid condition

Target Population

Age Range: 18

Sex: Either

Nature of Intervention: Any

Stakeholders Involved

- Clinical experts
- Consumers (caregivers)
- Consumers (patients)
- Methodologists
- Other
- Researchers

Study Type

- COS for clinical trials or clinical research
- COS for practice


- Consensus meeting
- Delphi process
- Literature review
- Survey

The PC-COS project comprised three stages: (1) a literature review to identify post-COVID-19 outcomes for consideration by the participants, also this inital list of outcomes came from a patient survey and recommendations from the steering committee; (2) a two-round online modified Delphi consensus process to rate the importance of the selected outcomes for a COS; and (3) an online interactive consensus meeting to review and agree upon the final COS.