GP-Update | Asthma-COPD overlap syndrome

I’m sure we’ve all had patients, perhaps smokers with childhood asthma, who present with breathlessness +/- cough and maybe odd spirometry findings? Is this COPD or asthma? As GPs, we know most patients don’t fit neatly into one diagnosis as guidelines often suggest! Thankfully, GOLD and GINA have produced guidance on asthma-COPD overlap syndrome (ACOS) (Diagnosis of Disease of Chronic Airflow Limitation: Global Initiative for Asthma, 2014), based on evidence and expert consensus.

Why is this important for GPs?

  • Probably underdiagnosed (thought to have 10-20% prevalence in COPD patients; Thorax 2015, doi:10.1136/thoraxjnl-2014-206740).
  • Increased risk of exacerbations (and possibly resultant lung function decline) which may be reduced by stepping up inhalers.
  • Because of an asthma component, inhaled corticosteroids (ICS) are important, at a time of reduced usage in COPD.

Pathology

This is debated: is ACOS a consequence of smoking damage in asthmatics or a specific phenotype of asthma? Some features of ACOS can exist as early as childhood, with airway limitation and smaller than expected tubes on CT scanning.

Diagnosis

First described in 2009, there is still no agreed definition. The challenge may be recognising when someone is developing COPD symptoms alongside their asthma.

Typical features include:

  • Usually >40y with smoking history.
  • Often PMH asthma/asthma-type symptoms in childhood.
    • ACOS commoner if more severe childhood asthma
  • Often FH asthma/allergies.
  • Respiratory symptoms persistent but variability may be prominent.
  • Symptoms significantly reduced by treatment but don’t resolve completely.
  • Progressive symptoms.
  • Exacerbations may be commoner than in COPD; frequency usually reduced by stepping up treatment.
  • Spirometry shows airflow limitation which is not fully reversible.

The guidelines suggest using these markers to help us by ticking each feature present in both the asthma and COPD columns:

  • If ≥3 features of one diagnosis, this suggests that condition is the main diagnosis.
  • However, if similar number of ticks for both conditions, consider ACOS.

Features Asthma COPD
Age of onset · <20y · ≥40y
Pattern of symptoms · Variability; Triggered by exercise/emotions/ dust/allergen exposure; Worse at night/early morning. Persistence of symptoms despite treatment; Daily symptoms and exertional dyspnoea; Chronic cough and sputum preceded onset of dyspnoea (dyspnoea unrelated to triggers).
Progression No worsening over time but can vary from season to season and year to year. Slowly worsening over time.
Lung function Variable airflow limitation; Lung function normal between symptoms. Persistent airflow limitation (post-bronchodilator FEV1/FVC <0.7); Lung function abnormal between symptoms.
PMH/FH FH asthma and/or allergies; Previous doctor diagnosed asthma. Heavy exposure to risk factors (smoking or open fires); Previous doctor diagnosed COPD or chronic bronchitis or emphysema.
Response to treatment  May improve spontaneously/have immediate response to bronchodilators/respond over weeks to ICS.  Short-acting bronchodilators provide only limited relief.
CXR Normal Severe hyperinflation.

Management

  • Evidence base is limited. The GINA/GOLD guideline suggests:
  • Smoking cessation.
  • Vaccinations (flu, pneumovax).
  • Pulmonary rehabilitation if indicated.
  • Drug therapy
    • Short-acting beta-agonists for relief.
    • Use ICS.
    • Consider LABA+/-LAMA in addition to ICS. In small trials, tiotropium led to lung function improvements in ACOS(Curr Allergy Asthma Resp 2015;15:7).
    • Don’t use LABA alone (safety concerns if used alone in asthma).
  • Safety of beta-blockers unknown, avoid in ACOS.
  • No guidance exists on management of exacerbations.

 

Aimee Lettis

Aimee Lettis from the GP Update team gives us short, sharp nuggets of clinical information for sessional GPs. The GP Update team run one-day courses, bringing GPs up to date with all the latest evidence and guidelines.

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