COPD maintenance trials use heterogeneous outcomes and measurement instruments: a systematic literature review

Randomised controlled trials (RCTs) of COPD management assess heterogeneous outcomes with diverse instruments and often omit those important to patients and healthcare professionals, limiting interpretability and comparability. This review aimed to identify the outcomes and instruments used in phase III/IV COPD maintenance management RCTs and assess their consistency.

We systematically reviewed all phase III/IV RCTs registered on ClinicalTrials.gov between 2010 and 2025 evaluating COPD maintenance management. Outcomes and measurement instruments were extracted from registry entries and categorised using the COMET (Core Outcome Measures in Effectiveness Trials) taxonomy. Registered outcomes from a random 10% sample were compared with the corresponding publications to assess concordance. Outcome frequencies were summarised across intervention types and sponsor categories.

43 unique outcomes were identified across 240 eligible RCTs. Physiological (89.5%), clinical (85.0%) and life impact outcomes (63.8%) were most frequently assessed, whereas resource use (39.6%), safety (36.7%) and mortality (16.7%) outcomes were less commonly reported. Only lung function (76.3%) and health-related quality of life (57.5%) appeared in over half of the trials. Exacerbations were reported in 40.4% of studies, while several patient-prioritised outcomes, particularly activities of daily living (5.4%) and exercise tolerance (18.3%), were infrequently assessed. Industry-sponsored RCTs more often reported lung function, resource use and adverse events; non-industry trials more frequently included biomarkers. Concordance between registered and published outcomes was acceptable (79.7%), although safety outcomes and instruments were sometimes under-reported.

COPD maintenance management RCTs show substantial heterogeneity and incomplete assessment of patient-prioritised outcomes. An internationally representative, multi-stakeholder core outcome set is urgently needed to improve consistency and patient-centred evaluation in future trials.