5th January 2024

Diagnosis

Diagnosis of COPD is suspected based on signs and symptoms and is supported by spirometry.

Investigations 

Spirometry

Spirometry should be performed at diagnosis to reconsider diagnosis if alternative diagnosis is likely and to monitor disease progression.

Post-bronchodilator spirometry should be performed to confirm diagnosis of COPD.

Other investigations

For initial diagnostic evaluation, in addition to spirometry, all patients should have the following:

• Chest radiograph to exclude alternative pathologies such as bronchiectasis and to look for typical signs of COPD. Frontal and lateral chest radiographs in patients with emphysema may reveal flattening of the diaphragm, increased retrosternal air space, long and narrow heart shadow. Patients with chronic bronchitis may show cardiomegaly and increased bronchovascular markings.
• Full blood count to assess for anaemia or polycythemia.
• BMI should be calculated, as patients with abnormal BMI should be referred for dietetic advice.
• Sputum culture in case of purulent and persistent sputum
• Serial home peak flows to exclude asthma if diagnosis is unclear
• ECG, natriuretic peptides and echocardiogram to assess cardiovascular status in case of cardiac disease or if pulmonary hypertension is suspected.
• CT scan of chest to assess suitability for lung reduction surgeries and investigate the following
  • Abnormalities seen on plain chest radiograph
  • Signs suggestive of other lung pathologies
  • Symptoms that are disproportionate to spirometry findings
• Transfer factor for carbon monoxide (TLCO) might be needed to investigate symptoms disproportionate to spirometric impairment and evaluate suitability for lung volume reduction surgery.
• Serum alpha-1 antitrypsin can be measured to assess for deficiency in younger patients and minimal smoking history or family history.

Reversibility testing

Routine spirometric reversibility is not necessary for diagnosis or planning initial therapy for most people. However, when diagnosis remains uncertain, or both asthma and COPD are present, the following findings can help to identify asthma:

• Over 400 ml response to bronchodilators.
• Over 400 ml to 30 mg oral prednisolone daily for 2 weeks.
• Serial peak flow measurements showing 20% or more of diurnal variability.

Classifying the severity of airflow obstruction

NICE. Recommendations | Chronic obstructive pulmonary disease in over 16s: diagnosis and management | Guidance | NICE [Internet]. Nice.org.uk. NICE; 2018. Available from: https://www.nice.org.uk/guidance/ng115/chapter/Recommendations#diagnosing-copd