Idiopathic Pulmonary Fibrosis

Essentials

• Idiopathic pulmonary fibrosis (IPF) is the most common subtype of usual interstitial pneumonias (UIP); it usually leads to progressive pulmonary fibrosis.
• Aetiology is unknown and the prognosis is poor in the majority of cases; however, the course of the disease shows significant variation. In a number of patients, an acute exacerbation may occur at any phase of the disease.
• Signs and symptoms are often initially nonspecific, and delays in diagnosis are therefore common.
• Diagnosis is confirmed in specialist health care.
• No curative drug therapy is known as yet. Pirfenidone and nintedanib may slow disease progress and prevent periods of exacerbation.
• A lung transplant is a feasible treatment option in some cases.

Epidemiology

• The worldwide prevalence estimates vary, ranging from 3 to 45 cases per 100 000 in the general population http://pubmed.ncbi.nlm.nih.gov/34233665/.

Symptoms

• The patient often gives a long history of cough before diagnosis. Dyspnoea develops as the disease progresses. Fever is not common.

Clinical findings

• At the initial stages both lung auscultation and investigation results may be normal.
• However, fine inspiratory crackles are often audible already at diagnosis (audio samples Fibrotising Alveolitis Associated with Rheumatoid Arthritis Fibrotising Alveolitis).
• Watch-glass nails and digital clubbing is seen in some patients.
• Findings consistent with right ventricular strain are associated with advanced disease.

Investigations

Diagnosis

• Diagnosis is confirmed in specialist health care.
• When a suspicion of IPF is aroused the principal task is to exclude other possible fibrotic lung diseases that resemble UIP, including other progressive pulmonary fibrosis (PPF), asbestosis Asbestos-Related Diseases, interstitial lung diseases associated with rheumatoid arthritis or other connective tissue disorders, chronic allergic alveolitis Allergic Alveolitis, pulmonary drug reactions and specific genetic syndromes.
• Serological tests are performed based on case-specific assessment.
• If HRCT demonstrates typical or probable UIP in accordance with the current classification (ATS/ERS), and other possible fibrotic lung diseases resembling UIP have been excluded, diagnosis can be made by clinical picture and the HRCT pattern.
• If the HRCT pattern meets the criteria for indeterminate for UIP, or alternative diagnosis (inconsistent with UIP), diagnostic investigations should be continued, provided that the patient's condition allows it. A bronchoscopy with bronchoalveolar lavage (BAL) and investigation of a lung tissue biopsy may be performed as additional examinations. Histological analysis of a lung biopsy is necessary only in a small portion of patients.
  • Before a lung biopsy, the patient's suitability to the procedure must be ascertained. The level of risk of surgical lung biopsy may be too high for some patients, e.g. due to disease severity, comorbidities or advanced age. According to the ATS/ERS guideline, the biopsy may be taken during bronchoscopy with cryobiopsy or as a surgical lung biopsy during endoscopic surgery.
  • Surgical lung biopsy can either be carried out as video-assisted thoracoscopic surgery (VATS) or an open lung biopsy procedure. It is recommended that several biopsies are obtained from at least two, preferably three, lobes of the lungs. The ATS/ERS guideline recommends VATS biopsy.
  • Cryobiopsy is performed during bronchoscopy. Several samples should preferably be taken.
• The final diagnosis is decided in a multidisciplinary discussion (MDD) involving a pulmonologist, radiologist and a pathologist and, if needed, a rheumatologist. In practice, participants can join an MDD in several ways, either in a face-to-face meeting, or over remote connection, using the internet, for example.
• Typical findings on spirometry include a decline in FVC (forced vital capacity), i.e. a restrictive defect, and reduced diffusion capacity.

Treatment

• The treatment of IPF is the responsibility of specialist health care. Follow-up treatment and monitoring may, however, be carried out in primary health care.
• No curative drug therapies are available to date.
• PirfenidoneNon-Steroid Agents for Idiopathic Pulmonary Fibrosis or nintedanib may be used to treat patients who have IPF according to the current diagnostic criteria and FVC between 50% and 90%.
  • Stopping smoking is recommended for those using pirfenidone.
  • Country specific regulations govern the reimbursement status of pirfenidone and nintedanib.
  • At present, pirfenidone is only indicated for the treatment of IPF. Nintedanib may be used for the treatment of IPF and other progressive pulmonary fibroses defined with specific criteria.
• Gastro-oesophageal reflux disease (GERD) Gastro-Oesophageal Reflux Disease is treated only if the patient is symptomatic.
• The latest international guideline recommends the use of oxygen therapy Domiciliary Oxygen for Interstitial Lung Disease and pulmonary rehabilitation Pulmonary Rehabilitation for Interstitial Lung Disease. Moreover, palliative symptomatic treatment is important especially as the disease progresses.
• The patient's suitability for lung transplantation should be assessed whenever IPF is diagnosed.

Prognosis

• Based on study data, the mean life expectancy is 3-5 years. The course of the disease may, however, be slower in some patients.
• The course of the disease varies greatly from patient to patient. In some patients the disease may progress slowly or remain stable even for several years, whereas others may have acute exacerbations leading to severe respiratory insufficiency.
• Individual patients may also experience different stages of disease progress.