What is an exacerbation of chronic obstructive pulmonary disease (COPD)?

COPD exacerbation definitions have been spelled out in different ways through different guidelines and criteria by institutions such as GOLD, NICE, and ATS, but all these definitions basically say the same thing.

An acute exacerbation or a flare-up of chronic obstructive pulmonary disease (COPD) is a sustained worsening of respiratory symptoms that is acute in onset and usually drives the patient to seek medical help or change of treatment.

COPD exacerbation classifications, however, vary because they have been created using different standards.

A primary requirement for an exacerbation to be diagnosed as a COPD exacerbation is that the patient primarily is a diagnosed and confirmed case of the COPD disease.

They have also been classified according to their severity, frequency, acceleration of symptoms, and the necessary change in treatment.

A  COPD exacerbation is characterized by a flare-up or worsening of the existing COPD symptoms such as a cough with sputum and breathlessness. These cardinal symptoms suddenly intensify causing you great discomfort and may require hospitalization. the changes in symptoms include:

  • A cough that increases in frequency and severity
  • Sputum production increases in volume and/or changes character and color
  • Dyspnea increases in severity and frequency

The principal identified causes of COPD exacerbations include

  • bacterial and/or viral infections – major cause accounting for 50% of the cases
  • air  pollution
  • cold weather and
  • interruption of regular treatment

COPD exacerbations are not common in the early stages of the disease and are largely a sign of moderate to severe cases. Furthermore, it is seen that in people with regular sputum production, the frequency of the flare-ups is more, and again, such people have an accelerated decline in FEV1 with a faster worsening of the prognosis.

Even then, 20% of the moderate to severe cases of inhaled steroids have no exacerbations during the initial three years.

COPD flare-ups have been associated with worsening of the lung function, increased frequency of hospitalization, and an increase in mortality rate.

Once the first exacerbation event has occurred, it tends to recur with increasing frequency and severity.

The ultimate outcome can lead to respiratory failure and eventual death from COPD itself or associated cardiovascular complications.

Defining COPD exacerbations

An exacerbation of COPD is defined as an event in the natural course of the disease characterized by a change in the patient’s baseline dyspnea, cough, and/or sputum that is beyond normal day-to-day variations; is acute in onset, and may warrant a change in the ongoing medication.

The American Thoracic Society (ATS) and European Respiratory Society (ERS) define an exacerbation as an

“acute change in a patient’s baseline dyspnea, cough, or sputum that is beyond normal variability, and that is sufficient to warrant a change in therapy”.

The Global Initiative for Chronic Obstructive Lung Disease (GOLD), the National Heart, Lung, and Blood Institute (NHLBI), and the World Health Organization (WHO), define a COPD exacerbation as

“an acute event characterized by a worsening of the patient’s respiratory symptoms that is beyond normal day-to-day variations and leads to a change in medication”

Another symptoms-based classification based on duration defines a COPD exacerbation as characterized by

“increase in dyspnea, cough or associated with a change in quality and quantity of sputum that led the patient to seek medical attention and lasts for at least 3 days”.

Another treatment-based classification defines COPD exacerbation as

a worsening of respiratory symptoms that require treatment with oral corticosteroids or antibiotics, or both.

COPD exacerbations can be mild, moderate, or severe.

  • Mild exacerbations of COPD may be defined as increased breathlessness, possibly associated with increased cough and sputum production, which force the patient to seek medical attention outside the hospital.
  • Severe COPD exacerbations may be defined when they are associated with acute or chronic respiratory failure using standard criteria based on arterial blood-gas measurement while breathing room air.

COPD exacerbations differential diagnosis

Many other conditions can mimic the symptoms presented by the COPD flare-up and therefore, it may be difficult to diagnose the condition during the first episode.

A COPD flare-up may be easily confused with:

  • A severe asthmatic exacerbation in an old asthmatic patient who smokes
  • Bronchiectasis flare-up of symptoms
  • Existing COPD comorbidities should be excluded before labeling the symptoms as those of COPD exacerbation. These include heart failure, pulmonary embolism, rib fracture, pneumothorax, pneumonia, and bronchial carcinoma.

Classification of COPD exacerbations 

Classification of disease becomes important to gather information on the incidence, prevalence, and treatment modification.

COPD exacerbations are classified in several ways. A treatment-based classification is given:

  • Level I – treated at home
  • Level II – requires hospitalization
  • Level III – leads to respiratory failure

This classification has its limitations because it classifies all admitted patients with respiratory failure. Secondly, the criteria for hospital admission vary from country to country and similarly from hospital to hospital.

The proposed classification as per the severity of the flare-up of the recent American Thoracic Society (ATS) and European Respiratory Society (ERS) statement includes three categories:

  • Mild –worsening of the respiratory symptoms, which are needed to be controlled with an increase in the dosage of the usual medication.
  • Moderate – exacerbations that require treatment with systemic corticosteroids and/or antibiotics;
  • Severe – exacerbations that require hospitalization or treatment at the emergency department. The most important sign of a severe exacerbation is a change in the mental status of the patient.

The American Thoracic Society/European Respiratory Society guidelines suggest a further classification based on the patient’s symptoms and signs to facilitate appropriate treatment.

  • Level I patients with mild-to-moderate COPD and no complications can be treated on an outpatient (OPD) basis.
  • Level II patients with moderate-to-severe COPD and the presence of complications require hospitalization.
  • Level III patients who are unstable with severe COPD and the presence of one or more additional health disorders (or diseases) require treatment in an intensive care unit (ICU) to prevent and/or treat respiratory failure.

The classic definition of Anthonisen et al divided exacerbated COPD patients according to their symptoms:

Type 1 exacerbations:  increase in breathlessness, sputum volume, and sputum purulence;

Type 2 exacerbations:  the presence of two of these symptoms; and

Type 3 exacerbations:  the presence of one of these symptoms in addition to one of the following criteria:

  • an upper respiratory tract infection for the past 5 days
  • fever
  • increased wheezing and cough
  • an increase in  heart rate or respiratory rate by 20% compared with the patient’s baseline readings

There is another method that has been used to classify COPD exacerbations:

  • Frequent exacerbations with two or more episodes per year. These patients have an accelerated decline in physical activity and lung function due to more severe infection and inflammation. It helps to evaluate the degree of COPD disease.
  • Infrequent exacerbations are those with less than two episodes/ year.