Are asthmatics enrolled in randomized trials representative of real-life outpatients?

Background/Objective: This study was aimed at exploring to what extent populations enrolled in randomized controlled trials (RCTs) of inhalation combination treatment for mild/moderate asthma in adults are fully representative of 'real-life' populations. The following is a retrospective analysis of the clinical records of outpatient subjects with an ascertained diagnosis of asthma. Methods: A retrospective analysis was performed. Stable conditions, such as smoking habit and chronic diseases other than asthma, were identified as exclusion criteria for RCTs. The selected criteria were then applied to asthmatic outpatients, yielding a population that was potentially eligible for RCTs. Results: Out of 1,909 subjects, 824 (43.2%) met at least one of the exclusion criteria for RCTs. Cigarette smoking (occurring in 34.3% of the entire population), lung diseases other than asthma (5.0%), anxiety and depression (3.3%), arrhythmias (2.3%), and coronary artery disease (1.2%) would have been the most frequent causes for exclusion from RCTs. The proportion of patients excluded from RCTs appears to increase with age, reaching 57.1% in patients aged >85 years. Conclusions: In a real-life setting, >40% of subjects with mild/moderate asthma are currently treated by protocols based on the results of RCTs for which they would not have been eligible. This proportion increases in elderly patients with comorbidities. These findings limit the generalizability of RCTs and advocate that complementary pragmatic studies be conducted.