Idiopathic Pulmonary Fibrosis (IPF)

What happens in IPF

The lungs contain millions of tiny air sacs (alveoli) surrounded by thin walls (the interstitium) where oxygen crosses into the blood. In IPF, repeated microscopic injury to the cells lining the air sacs leads to abnormal healing: fibroblasts lay down excess collagen, and scar tissue builds up. The lungs become stiff and smaller, and gas exchange worsens. In advanced disease, the lungs develop a "honeycomb" appearance on CT.

IPF is the most common form of interstitial lung disease of unknown cause. "Pulmonary fibrosis" more broadly can result from known causes such as asbestos, autoimmune diseases, medicines or hypersensitivity pneumonitis. See pulmonary fibrosis.

Symptoms

• breathlessness, first with exertion such as climbing stairs, gradually occurring with less activity
• dry, persistent cough, often triggered by talking or deep breaths
• fatigue and reduced exercise tolerance
• unintended weight loss
• clubbing: rounded, enlarged fingertips with curved nails, in up to half of people
• "Velcro" crackles heard with a stethoscope at the lung bases

Symptoms often develop over months to years and are commonly put down to aging, being out of shape or heart disease, which delays diagnosis.

Risk factors

• age: most diagnosed after 60
• male sex
• smoking, current or past
• occupational and environmental exposures: metal and wood dust, farming, stone cutting
• genetics: familial pulmonary fibrosis, MUC5B and telomere-related gene variants
• gastroesophageal reflux, which may contribute through repeated micro-aspiration
• viral infections may play a role

Diagnosis

Diagnosing IPF requires excluding other causes of fibrosis. Guidelines recommend a multidisciplinary discussion among lung specialists, radiologists and pathologists.

• History: exposures, medicines (such as amiodarone, nitrofurantoin, methotrexate), autoimmune symptoms, family history and birds or mold at home.
• High-resolution CT (HRCT): the key test. A usual interstitial pneumonia (UIP) pattern, with scarring and honeycombing at the bases and edges of the lungs, can confirm the diagnosis in the right setting without biopsy.
• Lung function tests: reduced lung volumes (restriction) and reduced gas transfer (DLCO).
• 6-minute walk test: distance and oxygen levels during exercise.
• Blood tests for autoimmune diseases such as rheumatoid arthritis, scleroderma and myositis.
• Bronchoscopy, cryobiopsy or surgical lung biopsy when CT is not conclusive.

Treatment

Antifibrotic medicines

• Nintedanib and pirfenidone slow the decline in lung function by roughly half and reduce acute exacerbations. They do not reverse existing scarring.
• Side effects include diarrhea and liver enzyme rises (nintedanib), and nausea, loss of appetite and sun-sensitive rash (pirfenidone). Liver blood tests are monitored.
• Newer treatments are being studied, and a further antifibrotic has been approved in some regions.

Steroids and immune-suppressing drugs are not recommended for IPF; a major trial showed that combining prednisone, azathioprine and N-acetylcysteine was harmful.

Supportive care

• Pulmonary rehabilitation: supervised exercise and education that improve breathlessness, exercise capacity and quality of life.
• Oxygen therapy for low oxygen levels at rest or during exercise.
• Vaccines: flu, COVID-19, pneumococcal and RSV.
• Stop smoking.
• Treat reflux if symptomatic, and screen for sleep apnea and pulmonary hypertension.
• Cough management and palliative care for symptoms such as breathlessness and anxiety.

Lung transplant

Lung transplantation can improve survival and quality of life for suitable patients, typically under about 65 to 70 without major other health problems. Early referral is recommended because waiting lists and evaluation take time.

Acute exacerbations

A sudden worsening over less than a month, often with new lung changes on CT, is serious. It is treated in hospital with oxygen and supportive care, often with steroids, although evidence for them is limited.

Outlook

IPF progresses differently in each person. Some stay stable for years. Others decline more quickly. Historically, average survival after diagnosis was around 3 to 5 years, but antifibrotic drugs, earlier diagnosis and better supportive care are improving outcomes. Complications include lung cancer, pulmonary hypertension, heart disease and infections. Planning for future care, including advance directives, is part of good management.

Frequently asked questions

What is idiopathic pulmonary fibrosis?

IPF is a chronic, progressive lung disease in which lung tissue becomes thickened and scarred for no known reason. The scarring makes it harder for oxygen to pass into the blood, causing breathlessness and cough that gradually worsen.

What are the early symptoms of IPF?

Early symptoms include breathlessness during activities such as walking uphill or climbing stairs, a persistent dry cough and fatigue. Doctors may hear crackles in the lungs, and some people develop clubbed fingertips. These are often mistaken for normal aging.

What causes idiopathic pulmonary fibrosis?

By definition the cause is unknown. Risk factors include age over 60, male sex, smoking, dust exposures, a family history and certain gene variants, and possibly acid reflux. Researchers think repeated injury to the air sacs triggers abnormal healing and scarring.

What is the life expectancy with IPF?

Historically, average survival was about 3 to 5 years after diagnosis, but it varies widely, and some people live much longer. Antifibrotic drugs slow progression, and lung transplant can extend life for suitable candidates. Your specialist can discuss your individual outlook.

Can pulmonary fibrosis be reversed?

Existing scarring cannot currently be reversed. Nintedanib and pirfenidone slow further scarring, and pulmonary rehabilitation and oxygen improve how people feel and function. Lung transplant replaces the scarred lungs in suitable patients.