Improving the diagnosis of asthma is the first step to improving outcomes. At a global level asthma is both
under- [2] and over-diagnosed [15– 18], 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.
The new definition of asthma. “ Asthma is a heterogeneous disease, usually characterized by chronic airway
inflammation. It is defined by the history of respiratory symptoms such as wheeze, shortness of breath,
chest tightness and cough that vary over time and in intensity, together with variable expiratory airflow
limitation.” The term “ asthma” is now deliberately used as an umbrella term like “ anaemia” , “ arthritis”
and “cancer ” ; these terms are very useful for communication with patients and for advocacy, and they
facilitate clinical recognition of heterogeneous diseases that have readily recognisable clinical features in
common. By contrast with anaemia, arthritis and cancer, evidence about the underlying mechanisms in
asthma is much less well-established, with most existing evidence coming from patients with long-standing
and clinically severe asthma; further research in broader populations is needed. However, an overarching
principle in the new GINA report is the importance of individualising patient management not only by
using genomics or proteomics, but also with “humanomics ” [19], taking into account the behavioural, social
and cultural factors that shape outcomes for individual patients.
The word “ usually” in the definition of asthma has concerned some readers. The rationale is that,
although chronic airway inflammation is characteristic of most currently known asthma phenotypes, the absence of inflammatory markers should not preclude the diagnosis of asthma being made in patients with
variable expiratory airflow limitation and variable respiratory symptoms. This should not be taken to
suggest a lesser emphasis on anti-inflammatory treatment; on the contrary, as described below, indications
for inhaled corticosteroid (ICS) treatment have been expanded. Importantly, the definition also avoids past
assumptions about the relationship between airway inflammation, airway hyperresponsiveness, symptoms
and exacerbations, and the inclusion of heterogeneity in the definition reinforces the need for ongoing
research to identify specific treatment targets [20].
Practical tools for diagnosis of asthma. The key changes in this section are consequent upon the new
definition of asthma, and are aimed at reducing both under- and over-diagnosis. There is an emphasis on
making a diagnosis in patients presenting with respiratory symptoms, preferably before commencing
treatment, and on documenting the basis of the diagnosis in the patient’s medical records. The chapter
includes a table of specific criteria for documenting variable expiratory airflow limitation, a key component
of asthma diagnosis, for use in clinical practice or clinical research. Other tests used in diagnosis of asthma
are described in the report and appendix, with a reminder that statements in the literature about the
sensitivity and specificity of “diagnostic” tools must be interpreted in the light of the definition of asthma
that was used and the population that was studied; many studies, particularly those in which physician
diagnosis was the gold standard, have primarily included patients with a classical allergic asthma phenotype.
A list of common asthma phenotypes is provided, to prompt clinicians, including those in primary care, to
recognise different clinical patterns among their patients, even if they lack access to complex investigations.
Confirming the diagnosis of asthma in patients already on treatment. Evidence to support a diagnosis of
asthma is often not documented in case notes, and over-diagnosis is common (25– 35%) in developed
countries [15– 18]. Different approaches are suggested for confirming the diagnosis in patients already on
treatment, depending on their clinical status. Advice is provided about how to step down treatment if
needed for diagnostic confirmation, based on available evidence and practical considerations, such as
ensuring the patient has a written asthma action plan, and choosing a suitable time (no respiratory
infection, not travelling, not pregnant).
Diagnosis of asthma in special populations (e.g. pregnancy, occupational asthma, older patients, smokers
and athletes). These sections are consistent with the emphasis in GINA on tailoring asthma management
for different populations.