Improving the diagnosis of asthma is the first step to improving outcomes. At a global level asthma is both
under and over-diagnosed , with under-diagnosis contributing to unnecessary burden for
patients and families and increased costs for the health system, and over-diagnosis increasing treatment
costs and exposing patients to unnecessary risk of side-effects. Past “definitions” of asthma have been
lengthy descriptions, focusing on types of inflammatory cells, hyperresponsiveness, symptoms, and the
assumed relationship between these features. A key priority for GINA was that the new definition should
be feasible for use in diagnosing asthma in clinical practice, while also reflecting the complexity of asthma
as a heterogeneous disease; the definition also needed to display flexibility within the context of rapidly
emerging evidence that different mechanisms underlie the cardinal clinical features of variable respiratory
symptoms and variable expiratory airflow limitation by which asthma is defined.