What proportion of chronic obstructive pulmonary disease outpatients is eligible for inclusion in randomized clinical trials?

BACKGROUND AND
OBJECTIVE: We aimed to explore to what extent an unselected population of chronic obstructive pulmonary disease (COPD) outpatients would be eligible for inclusion in randomized clinical trials (RCTs).
METHODS: Retrospective analysis of the clinical records of outpatient subjects with an ascertained diagnosis of COPD. COPD outpatients were assessed against the following inclusion criteria: 40 < age < 80 years, current or former smokers, forced expiratory volume in the first second (FEV1) <70% predicted, no long-term oxygen therapy, no other concomitant lung diseases and absence of major extrapulmonary comorbidities. The study consisted of 2 phases; in phase 1, the criteria for inclusion in RCTs on COPD were selected, and in phase 2, the above criteria were applied to an unselected outpatient COPD population.
RESULTS: A total of 578 subjects (83% of the whole group) failed at least one of the inclusion criteria. Lung diseases other than COPD (occurring in 30% of our population, mostly bronchiectasis), long-term oxygen therapy (31%), FEV1 (19%), age (14%) and extrapulmonary comorbidities such as cognitive impairment (14%), arrhythmias (17%) and congestive heart disease (13%) would have been the most frequent causes for exclusion from RCTs.
CONCLUSIONS: In real-life settings, more than 80% of COPD subjects are currently treated by protocols based on results of RCTs for which they would not have been eligible. We encourage a more extensive use of pragmatic trials in COPD to better modulate the application of results of RCTs to patients encountered in daily practice.