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Asthma-COPD Overlap Syndrome

Up until recently, the chronic disease management of patients with chronic airways disease has categorised patients as suffering from either asthma or chronic obstructive pulmonary disease (COPD). However, it frequently poses a clinical dilemma as to which category a patient fits into. To assist us the various guideline bodies GOLD, GINA etc have cooperated and produce a new category of patient. This is the Asthma-COPD Overlap Syndrome (ACOS) patient.

ACOS

Background

For patients with respiratory symptoms, it’s important to distinguish between infectious causes, non-pulmonary causes, or chronic airway disease.

In patients with chronic airways disease, the differential diagnosis differs by age.

Children and young adults: most likely to be asthma.

Adults >40 years: COPD becomes more common.

However, distinguishing asthma from COPD has become more difficult as many patients with symptoms of chronic airway disease have features of BOTH asthma and COPD.

This has been called ACOS.

ACOS is not a single disease.

It is likely that a range of different underlying mechanisms and origins will be identified.

It is important to note that patients with features of both asthma and COPD have worse outcomes than those with asthma or COPD alone:

Frequent exacerbations.

Poor quality-of-life.

More rapid decline in lung function.

Higher mortality.

Greater healthcare utilisation. 

Reported prevalence of ACOS varies by definitions used

Concurrent doctor-diagnosed asthma and COPD are found in 15-20 per cent of patients with chronic airway disease.

Reported rates of ACOS are between 15-55 per cent of patients with chronic airway disease, depending on the definitions used for ‘asthma’ and ‘COPD’, and the population studied – this wide range highlights the importance of developing a concrete definition.

Stepwise approach for diagnosis and Iinitial treatment

1. Does the patient have chronic airway disease?

Clinical history (history of chronic or recurrent cough, dyspnoea, wheeze, previous diagnosis of asthma or COPD, treatment with inhaled medication, history of smoking).

Physical exam (may be normal, evidence of hyperinflation, wheeze, or crackles).

Radiology (CXR or CT; may be normal, air wall thickening, bullae, may identify diagnosis or suggest alternative).

Screening questionnaires (proposed primarily to aid in identifying patients at risk of chronic airway disease).

2. Syndromic diagnosis of asthma, COPD and ACOS (see Tables 1 and 2)

Assemble the features that favour a diagnosis of asthma or of COPD.

Compare the number of features on each side (if the patient has ≥3 features of either asthma or COPD, there is a strong likelihood that this is the correct diagnosis).

When a patient has a similar number of features of both asthma and COPD, consider the diagnosis of ACOS.

Consider the level of certainty around the diagnosis.

3. Spirometry

Essential if chronic airway disease is suspected

Confirms chronic airflow limitation.

More limited value in distinguishing between asthma with fixed airflow limitation, COPD and ACOS.

Measure at the initial visit or subsequent visit.

If possible, measure before and after a trial of treatment.

Medications taken before testing may influence results.

Although initial recognition and treatment for ACOS may be made in primary care, referral for confirmatory investigations is encouraged, as outcomes for ACOS are often worse than for asthma or COPD alone

4. Commence initial therapy

Initial pharmacotherapy choices are based on both efficacy and safety.

If syndromic assessment suggests asthma as single diagnosis:

Start with low-dose inhaled corticosteroids (ICS).

Add LABA and/or LAMA if needed for poor control despite good adherence and correct technique.

Do not give LABA alone without ICS.

If syndromic assessment suggests COPD as single diagnosis:

Start with bronchodilators or combination therapy.

Do not give ICS alone without LABA and/or LAMA.

If differential diagnosis is equally balanced between asthma and COPD, ie, ACOS:

Start treatment as for asthma, pending further investigations.

Start with ICS at low or moderate dose.

Usually also add LABA and/or LAMA, or continue if already prescribed.

For all patients with chronic airflow limitation: 

Treat modifiable risk factors including advice about smoking cessation.

Treat comorbidities.

Advise about non-pharmacological strategies including physical activity, and, for COPD or ACOS, pulmonary rehabilitation and vaccinations.

Provide appropriate self-management strategies.

Arrange regular follow-up.

5. Referral for specialised investigations (if necessary)

Persistent symptoms and/or exacerbations despite treatment.

Diagnostic uncertainty, especially if alternative diagnosis needs to be excluded (ie, CVD or TB).

Suspected airways disease with atypical or additional symptoms or signs (eg, haemoptysis, weight loss, night sweats, fever, or chronic purulent sputum). Do not wait for a treatment trial before referring.

Suspected chronic airways disease but few features of asthma, COPD or ACOS.

Comorbidities that may interfere with their management.

Issues arising during ongoing management of asthma, COPD or ACOS.

Future research

The understanding of ACOS is still at a preliminary stage and therefore an urgent need for more research is required in order to guide better recognition and appropriate treatment.

Further research is needed to inform evidence-based definitions and a more detailed classification of patients who present overlapping features of asthma and COPD, and to encourage the development of specific interventions for clinical use.

Key points

Distinguishing asthma from COPD can be problematic, particularly in smokers and older adults. Some patients may have clinical features of both asthma and COPD; this has been called ACOS.

ACOS is not a single disease. It includes patients with different forms of airways disease (phenotypes). It is likely that for ACOS, as for asthma and COPD, a range of different underlying mechanisms will be identified.

Outside specialist centres, a stepwise approach to diagnosing is advised, with recognition of the presence of a chronic airways disease, syndromic categorisation as characteristic asthma, characteristic COPD, or ACOS, confirmation of chronic airflow limitation by spirometry and, if necessary, referral for specialised investigation.

Although initial recognition and treatment for ACOS may be made in primary care, referral for confirmatory investigations is encouraged, as outcomes for ACOS are often worse than for asthma or COPD alone.

Recommendations for initial treatment, for clinical efficacy and safety, are:

For patients with features of asthma: Prescribe adequate controller therapy including ICS, but not long-acting bronchodilators alone (as monotherapy).

For patients with COPD: Prescribe appropriate symptomatic treatment with bronchodilators or combination therapy, but not ICS alone (as monotherapy).

For ACOS, treat with ICS in a low/moderate dose (depending on level of symptoms); add-on treatment with LABA and/or LABA is usually also necessary. If there are features of asthma, avoid LABA monotherapy.

All patients with chronic airflow limitations should receive appropriate treatment for other clinical problems, including advice about smoking cessation, physical activity, and treatment of comorbidities.

This consensus-based description of ACOS is intended to provide interim advice to clinicians, while simulating further study of the character, underlying mechanisms and treatments for this common clinical problem.

References on request

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