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10 February 2022

New study identifies 12 key outcomes to assess Long COVID treatments

Results from this international collaboration of experts and patients will accelerate research and development of approaches to manage and treat Long COVID.

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New pre-print research, co-authored by Dr Tim Nicholson from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN), has identified a set of core outcomes for Long COVID that are recommended for use in future research and clinical practice globally.

The outcomes, established via a large consensus study consisting of 1535 international experts and patients from 71 countries, identified 24 core outcomes of Long COVID in adults, 12 of which were considered a priority. These included fatigue, pain, and worsening of symptoms following physical or mental exertion, as well as changes to the cardiovascular, respiratory and nervous systems.

Establishing a set of clear outcomes will accelerate the development of evidence-based treatments for Long COVID by guiding the research community on collecting the most meaningful data on whether a treatment works. It will also ensure the consistency of measurements and allow for easier collation and comparison of results across clinical trials and other studies.

The rapid development of this Core Outcome Set for Long COVID by the global research community in partnership with patients with lived experience has achieved a key milestone in the development of evidence based treatments by allowing optimisation, coordination and efficient collation of data in research and clinical services

Dr Tim Nicholson, study co-author and Senior Clinical Lecturer at the Institute of Psychiatry, Psychology & Neuroscience, King's College London

COVID-19 symptoms persisting for more than months after the initial infection has gone are known as ‘Long COVID’ or ‘post-COVID syndrome’. Last year it was estimated that over 2 million people in the UK were living with Long COVID. While there are common features, patients can experience a wide range of other symptoms across all bodily systems, making identification of the key symptoms challenging.

Due to the breadth of possible symptoms, it is not feasible to measure all possible outcomes, and there needs to be a prioritisation that is agreed by all relevant stakeholders, from researchers and clinicians to patients and carers.

The study team identified all commonly reported outcomes in research to date, then used a ‘Delphi’ technique to reach consensus among the stakeholders. This is a well-established approach in which participants are asked their opinions in a first round, then shown the results of others and given the chance to rethink their views. This is repeated in subsequent rounds until consensus is achieved.

12 outcomes were prioritised for use in future clinical research studies and clinical practice: (1) Survival; (2) Fatigue; (3) Pain; (4) Post-exertion symptoms, and “functioning, symptoms and conditions” for (5) Cardiovascular, (6) Respiratory, (7) Neurological, (8) Cognitive, (9) Mental/psychiatric systems, (10) Overall physical function and (11) Work/occupational and study changes, and (12) ‘Recovery’. This was included as an additional outcome to achieve consistency with a previously published core outcome set for acute COVID-19.

Researchers must now go through a similar process to identify the best measures for assessing these outcomes. These will need to be feasible for use across the world, including in resource-poor settings. It will also need to be done on an accelerated timescale to inform treatment trials, other studies, and clinical services to meet this major new healthcare challenge.


The study was co-led with Dr Daniel Mublit (Imperial College London and Sechenov University Moscow) and Professor Paula Williamson (Liverpool University) and funded by the National Institute for Health Research (NIHR). It was conducted in collaboration with the World Health Organisation (WHO), the Core Outcome Measures in Effectiveness Trials (COMET) Initiative, the International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC) and many Long COVID patients and organisations, including Long COVID SOS.

For more information, please contact Patrick O’Brien (Senior Media Officer)

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Tim Nicholson

Reader in Neuropsychiatry