A Proposed Consensus Definition of Severe COPD: a modified Delphi Study

Advanced interventions are available for patients with more severe COPD despite guideline-recommended therapies, yet this population is heterogeneously defined and inconsistently recognized, and a standardized work-up is lacking, which could lead to mismanagement.

To formulate a new, expert-based consensus definition of severe COPD and a minimal set of diagnostics and characteristics to be assessed in the work-up of these patients.

A modified Delphi study with two online rounds was conducted between June 2024 and January 2025 with 55 international COPD experts representing all areas of disease management. Sixty-seven (round 1) and 20 (round 2) statements were tested in seven domains: (A) the need for a definition, (B) symptoms, (C) functional impairment, (D) quality of life, (E) physiological impairment, (F) framework definition, and (G) risk factors. Consensus was defined as ≥ 75% agreement.

Consensus was reached for 46 (69%) statements in round 1 and 15 (75%) in round 2. Among patients with confirmed COPD, severe COPD was defined as: (1) persistent symptoms, functional impairment, or severely reduced quality of life; (2) despite optimal treatment and not due to comorbidities; and (3) including at least one clinical characteristic: severe airflow obstruction, severely impaired diffusion capacity, severe hyperinflation, frequent exacerbations, chronic respiratory insufficiency, pulmonary hypertension related to COPD, or cachexia or unintentional weight loss related to COPD. The proposed standardized work-up comprised: (1) assessment of patient-reported outcomes for symptoms, quality of life, anxiety and depression; (2) assessment of exacerbation frequency and severity; (3) comprehensive diagnostic testing, including lung function testing, blood gas analysis, imaging, cardiac assessment, and exercise-tolerance testing; and (4) assessment of risk factors for more severe and progressive disease.

Using expert consensus, we devised an internationally-supported, proposed definition and work-up for 'severe COPD', accounting for disease heterogeneity. This definition may improve identification of the population and supports a structured evaluation of this often under-recognized and potentially undertreated population. Future studies are warranted to determine its clinical impact, prognostic value, and utility in research.