Educational Aims

To improve understanding of: • The relative benefits and limitations of evidence derived from different study designs and the role that real-life asthma studies can play in addressing limitations in the classical randomised controlled trial (cRCT) evidence base. • The importance of guideline recommendations being modified to fit the populations studied and the model of care provided in their reference studies. Key points • Classical randomised controlled trials (cRCTs) show results from a narrow patient group with a constrained ecology of care. • Patients with “real-life ” co-morbidities and lifestyle factors receiving usual care often have different responses to medication which will not be captured by cRCTs if they are excluded by strict selection criteria. • Meta-analyses, used to direct guidelines, contain an inherent meta-bias based on patient selection and artificial patient care. • Guideline recommendations should clarify where they related to cRCT ideals (in terms of patient populations, medical resources and care received) and could be enhanced through inclusion of evidence from studies designed to better model the populations and care approaches present in routine care