A Core Outcome Set for Clinical Trials on Post COVID-19 Condition: "What," "When," and "How" to Measure

To develop a core outcome set (COS) for clinical trials on post COVID-19 condition (PCC), that is, what, when, and how to measure PCC.

A comprehensive collection of outcomes (including their measurement methods and phases) was launched via literature review and clinician and patient surveys. Two rounds of Delphi surveys were conducted under the predefined criteria for rating, followed by a consensus meeting to finalize the COS for PCC (COS-PCC).

Fifty-two outcomes within 7 categories and 206 measurement methods were identified. Sixty participants from five stakeholder groups completed the first round of the Delphi survey and 41 the second. Consensus was reached among 36 representatives on four domains of respiratory, physical, neuropsychological, and health conditions, including nine core outcomes and their respective measurement methods of priority: dyspnea (modified Medical Research Council scale), cough (Leicester Cough Questionnaire), exercise capacity (6-min walk test), fatigue (Fatigue Severity Scale), pain (Numerical Rating Scale), sleeping disturbance (Pittsburgh Sleep Quality Index), anxiety (Generalized Anxiety Disorder Scale-7), depression (Patient Health Questionnaire-9), and health status (36-item Short Form Health Survey); 16 optional measurement methods achieved consensus for supplement. Measuring phases of each core outcome were prioritized by importance through short and long terms of PCC.

The COS-PCC highlights the key PCC concerns and provides an essential outcome set for PCC assessment in clinical trials and evidence synthesis. With improving the understanding of PCC and accumulating research evidence, the COS-PCC needs to be continuously updated and improved in practice.