What causes Chronic Obstructive Pulmonary Disease (COPD) exacerbation?

From the Guidelines

COPD exacerbations are primarily caused by respiratory infections, with viral and bacterial pathogens accounting for about 70-80% of cases, as stated in the 2017 Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Lung Disease report 1. The most common causes of COPD exacerbations are respiratory tract infections, which can be triggered by various factors, including viral and bacterial pathogens.

• Common viral triggers include rhinovirus (common cold), influenza, and respiratory syncytial virus, while bacterial culprits often include Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis, as mentioned in the 2017 report 1.
• Air pollution, both indoor and outdoor, significantly contributes to exacerbations by irritating airways and increasing inflammation, including exposure to particulate matter, nitrogen dioxide, sulfur dioxide, and ozone.
• Cigarette smoke remains a major trigger, as continued smoking worsens COPD progression and increases exacerbation frequency, as stated in the 2017 European Respiratory Society/American Thoracic Society guideline 1.
• Weather changes, particularly cold temperatures and high humidity, can provoke symptoms, and medication non-adherence is another important factor, as inconsistent use of prescribed inhalers and medications allows inflammation to progress unchecked.
• Less common causes include gastroesophageal reflux disease (GERD), heart failure, and pulmonary embolism, as mentioned in the 2015 American Thoracic Society/European Respiratory Society statement 1. Prevention strategies include vaccination against influenza and pneumococcal disease, proper inhaler technique, smoking cessation, avoiding air pollutants, and prompt treatment of respiratory infections, as recommended in the 2021 American Family Physician guideline 1.

From the Research

Causes of COPD Exacerbation

• Respiratory viruses and bacteria are the main triggers of COPD exacerbations, infecting the lower airway and increasing airway inflammation 2, 3, 4, 5
• Air pollution is also a significant cause of COPD exacerbations, leading to acute inflammation of the airways and lung 3, 4, 5
• Other factors that can contribute to COPD exacerbations include:
  • Prior exacerbations 4
  • Non-adherence to treatment 4
  • Associated comorbidities, such as heart failure and hypertension 3, 4, 5
  • Exacerbation of other respiratory diseases and non-respiratory diseases 3, 5

Mechanisms of COPD Exacerbation

• Acute inflammation of the airways and lung, leading to worsening of respiratory symptoms 2, 3, 4, 5
• Systemic inflammation, which can cause acute respiratory symptoms through decompensation of concomitant chronic diseases 3
• Hyperinflation, which can lead to increased airway resistance and worsening of symptoms 2

Risk Factors for COPD Exacerbation

• Respiratory tract infections 4, 5
• Various exposures, such as air pollution 4, 5
• Prior exacerbations 4
• Non-adherence to treatment 4
• Associated comorbidities, such as heart failure and hypertension 3, 4, 5