Originally published: March 2019

Key learning points

  • Idiopathic pulmonary fibrosis (IPF) is a progressive, scarring lung disease with a poor prognosis and a rising incidence
  • It is most common in men over 65 with a smoking history
  • Patients are often symptomatic for years and are frequently misdiagnosed as having COPD or asthma
  • The hallmark clinical finding is crackles on auscultation of the chest
  • At the early stages, chest X-ray and spirometry may be normal and a CT scan is the most sensitive means of making the diagnosis
  • Early diagnosis allows access to novel anti-fibrotic therapies that have been shown to slow down the progression of IPF and improve outcomes

Introduction

Idiopathic pulmonary fibrosis (IPF) is a progressive, scarring lung disease of unknown aetiology with a historic life expectancy of between three and five years from diagnosis.1 The incidence of IPF is rising. It is estimated that in the UK there are over 32,000 people with the condition, which is responsible for 1% of all deaths.2 IPF is most common in Caucasian men over the age of 65 who have a history of cigarette smoke exposure. Some individuals are genetically predisposed to the condition so it can be hereditary. Familial IPF demonstrates genetic anticipation in that patients often present at a younger age than their affected parent.

How to make the diagnosis

In its early stages, the symptoms of IPF are nonspecific and the most common presentation to primary care is with a persistent dry cough. Over time, breathlessness develops, and patients notice a decline in their exercise capacity. The symptoms of cough and breathlessness progress insidiously and may overlap with other respiratory conditions leading to a delay in diagnosis. Patients frequently spend up to five years with symptoms before they are diagnosed,and may be incorrectly labelled as having COPD or asthma.

The key to making the diagnosis is clinical examination. The hallmark finding of pulmonary fibrosis is the presence of fine end inspiratory crackles (Velcro-like) on auscultation of the chest.4 This feature should be a red flag, alerting clinicians to the possible diagnosis of IPF. While the presence of crackles can also signify respiratory tract infection or heart failure, there are usually other history, signs and symptoms that make these diagnoses more likely; so persistent crackles should raise the suspicion of IPF. The acoustics of the thoracic cavity means that crackles can first be auscultated in the axillae and special attention should be paid to this area during clinical examination.

As IPF progresses, the typical fine crackles become more pronounced at the lung bases where the disease is often most florid. Clubbing of the nails develops with time and when the condition advances further, pulmonary hypertension and right heart failure ensues.5 At this stage patients are invariably dependent on oxygen at rest and on ambulation.

The key investigation for the diagnosis of IPF is CT scanning and the identification of pulmonary fibrosis on a CT scan should prompt an urgent outpatient respiratory referral. When the disease is limited, the chest radiograph may be normal and spirometry will be preserved. Clinicians should not be falsely reassured by these tests when considering the diagnosis of IPF. Sometimes a bronchoscopy is required to differentiate IPF from other causes of pulmonary fibrosis, and rarely a lung biopsy may be needed to confirm the diagnosis.4

Summary of diagnosis of IPF
Symptoms
  • Persistent dry cough
  • Breathlessness
  • Decline in exercise capacity
Examination/tests
  • Auscultation of chest – fine end inspiratory crackles
  • CT scan – pulmonary fibrosis
  • Lung function – restrictive spirometry (reduced FVC and raised FEV1/FVC ratio)
  • Bronchoscopy may be required and, rarely, lung biopsy

Early detection of IPF allows initiation of treatment

It is important to remember that IPF has an outcome far worse than many cancers and so delays in diagnosis have grave consequences. This is all the more relevant as there are now two anti-fibrotic therapies approved for the treatment of IPF.6,7

On average as the disease progresses, untreated patients with IPF decline by approximately 250ml of their forced vital capacity (FVC) each year. However, treatment with either pirfenidone or nintedanib has been found to reduce that decline by 50% to approximately 125ml.6,7 There is emerging evidence that treatment may prolong life.8 Neither drug can reverse established fibrosis but both slow down the scarring process. Therefore, early detection of the condition and timely referral to respiratory services is key to achieving the best outcomes for patients with pulmonary fibrosis.

In the UK, antifibrotic therapies can only be prescribed at nationally commissioned specialist centres and their use is restricted to patients with an FVC between 50% and 80% of predicted.9,10 For this reason, early referral is crucial because if the disease progresses to below this threshold, treatment cannot be initiated.

Other treatment considerations

Access to clinical nurse specialists, palliative care services, oxygen therapy and pulmonary rehabilitation is of paramount importance in supporting both the patient and family, leading to an improved quality of life for patients with this serious and progressive condition.11 Ultimately, aside from lung transplantation, there is no cure for IPF so patients should be referred for lung transplant assessment in a timely fashion and preferably before pulmonary hypertension and right heart failure ensues.

Although IPF is one of the most common interstitial lung diseases, other conditions such as hypersensitivity pneumonitis, sarcoidosis or pulmonary fibrosis related to rheumatoid arthritis or scleroderma can have similar appearances on a CT scan. The treatment of these conditions differs and is based on immunosuppression with steroids and steroid-sparing agents. These treatments have been shown to be harmful for patients with IPF,12 hence the need for specialist input from a multidisciplinary team to confirm the diagnosis.

Outlook

Research into IPF is rapidly expanding and our understanding of the condition is progressing. Furthermore, clinical trials of new therapies for this condition are ongoing.13,14 Therefore the outlook for patients with IPF is more positive than it has ever been before. The focus of the medical community should be on making the diagnosis as early as possible so that we can start to improve outcomes for patients with this condition.

Dr Peter George is clinical lead for interstitial lung disease at Royal Brompton Hospital, London

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