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Idiopathic Pulmonary Fibrosis

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Overview

Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD). ILD is an umbrella term for a group of respiratory diseases affecting the lung interstitium (the tissues and space around the alveoli).

Lung fibrosis is where the interstitium of the lungs is replaced with scar tissue, leading to less elasticity and expandability in the lungs (reduced compliance), giving rise to the signs and symptoms seen. It can happen secondary to lung damage (e.g. an acute infection such as pneumonia or tuberculosis), exposure to irritants (e.g. coal dust), or it can be idiopathic (IPF).

IPF is used to describe lung fibrosis where there is no identifiable underlying cause.

Causes of Lung Fibrosis

Upper zone fibrosis

Can be remembered using the mnemonic CHAARTSS:

Lower zone fibrosis

Can be remembered using the mnemonic RASIO:

Epidemiology

  • IPF is the most common ILD
  • Incidence is around 7 per 100,000
  • Median age of presentation is 70 years
  • More common in people who smoke or have a history of smoking
  • IPF is more common in men

Risk Factors

  • Increased age
  • Smoking
  • Family history
  • Occupational exposure e.g. silica or asbestos exposure, and raising livestock/birds 

Presentation

Patients may have:

Differential Diagnoses

Lung cancer

  • Patients may have signs and symptoms of paraneoplastic syndromes
  • Auscultation may reveal focal areas of dullness/wheezes

Investigations

All patients

  • Chest x-ray:
    • May show basilar reticular opacification
  • Spirometry and lung function tests:
    • Usually shows a restrictive picture:
      • FEV1 normal or decreased
      • FVC decreased
      • FEV1/FVC ratio >0.7 (increased)
    • Transfer factor (TLCO): decreased
  • High-resolution CT chest:
    • Shows ground-glass or opacification or honeycombing

Management

Overview

General principles of management are:

  • Most patients have pulmonary rehabilitation
  • Some medications may be used e.g. pirfenidone
  • Supportive care such as oxygen and physiotherapy

Monitoring

  • Patients are generally followed up every 3 months or sooner if their condition is rapidly worsening
  • They may be followed up every 6 months and then annually if they have stable disease

Complications

Prognosis

  • Median survival after diagnosis is around 2.5 years
  • The prognosis for pulmonary fibrosis varies significantly depending on if there is an underlying cause and if the patient has any comorbidities

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