Idiopathic pulmonary fibrosis is a serious disease where the alveoli (the tiny air sacs of the lungs) and the lung tissue next to the alveoli become damaged and scarred. The main symptom is shortness of breath that gradually gets worse. The exact cause is not known. Treatments include steroids, and other medicines, and increasingly lung transplantation may be offered.
Understanding the lungs and alveoli
What is idiopathic pulmonary fibrosis and what causes it?
It is useful to understand what the following words mean:
- Idiopathic and cryptogenic mean 'of unknown cause'.
- Pulmonary means 'affecting the lungs'.
- Fibrosis means 'thickening' or 'scarring'.
- Alveolitis means 'inflammation of the alveoli'.
Idiopathic pulmonary fibrosis used to be called cryptogenic fibrosing alveolitis. The exact cause is not known (hence the term idiopathic). It was thought that inflammation within the alveoli played a big role in the development of idiopathic pulmonary fibrosis and that this inflammation led to scarring and fibrosis. This led to the name cryptogenic fibrosing alveolitis. However, treatments that help to reduce inflammation are not always effective. Therefore, the role of inflammation has recently been brought into question.
The current thinking is that somehow the cells that line the alveoli are damaged in some way. The cells then try to heal themselves. But, this healing process becomes out of control, causing thickening and damage to the walls of the alveoli, and fibrosis (scarring) of the alveoli and lung tissue. The thickening and scarring reduces the amount of oxygen that can pass into the blood vessels from affected alveoli. Therefore, as the disease progresses, less oxygen than normal is passed into the body when you breathe.
Various things have been suggested as potential causes, or triggers, of the initial damage to the cells lining the alveoli. These include:
- Cigarette smoking. The disease is more common in people who smoke or have been smokers at some time.
- Viral infections. These include viruses such as the Epstein-Barr virus that causes glandular fever, and the hepatitis C virus.
- Certain medicines.
- Pollutants in the environment.
- Gastro-oesophageal reflux disease. This is where there is long-standing reflux of stomach contents into your gullet, which you may then inadvertently inhale into your lungs. See separate leaflet called Acid Reflux and Oesophagitis for more detail.
Idiopathic pulmonary fibrosis also seems to run in some families. However, in about 4 out of 5 cases, there is no family history of the disease.
(A similar fibrotic lung condition sometimes occurs as a result of exposure at work to certain metals, wood dusts and other chemicals, and as a side-effect to certain medicines. These conditions are not idiopathic, as the cause can be identified. If you have suspected lung fibrosis, your doctor is likely to ask you about your work history to rule out these conditions.)
How common is idiopathic pulmonary fibrosis?
It is rare. Fewer than 3 in 10,000 people develop this disease. However, it seems to be getting more common. It can affect anybody at any age but it most commonly develops between the ages of 50 and 70. It seems to be more common in men than in women.
What are the symptoms of idiopathic pulmonary fibrosis?
Symptoms tend to develop gradually:
- Breathlessness (shortness of breath) that gradually becomes worse is the main symptom. This is due to the reduced amount of oxygen that gets into the bloodstream. Shortness of breath on exertion may be noticed at first. This may be passed off as 'just getting older' for a while until the shortness of breath gets worse.
- A dry cough often develops (a cough with little or no sputum).
- Finger or toenail clubbing occurs in about half of cases. Clubbing is a painless swelling at the base of the nails. The cause of clubbing is not clear. It occurs in people with various chest and heart diseases.
- An increased risk of developing chest infections.
As the condition progresses, symptoms can sometimes quickly become worse (called an acute exacerbation). Periods of worse symptoms may be followed by periods where there seems to be some improvement. If the condition becomes severe then heart failure may develop. This is due to the reduced level of oxygen in the blood and changes in the lung tissue, which can cause an increase in pressure in the blood vessels in the lungs. This increase in pressure can put a strain on the heart muscle, leading to heart failure. Heart failure can cause various symptoms including worsening breathlessness and fluid retention.
How is idiopathic pulmonary fibrosis diagnosed?
The above symptoms, combined with crackles heard by a doctor listening to your lungs with a stethoscope, can suggest the diagnosis. A chest X-ray may show a typical scarring pattern in the lungs, suggestive of the disease. Special breathing tests can also show changes that raise suspicion. Your doctor may advise that they refer you to a chest specialist if they suspect that you have idiopathic pulmonary fibrosis.
To confirm the diagnosis, and to assess the severity of the disease, a CT scan of the lung and/or a lung biopsy are usually needed.
A special type of CT scanning, called high-resolution CT (HRCT) scanning, is commonly used. A lung biopsy is where a small sample of lung tissue is taken by a small operation. A keyhole procedure is normally used. The sample is looked at under a microscope. Idiopathic pulmonary fibrosis causes a typical appearance of the alveoli and nearby lung tissue. This can be seen when the biopsy sample is examined. Sometimes the specialist may suggest that they take samples of your lung cells in another way to examine them. This is usually done through a procedure known as a bronchoscopy. A small, flexible telescope is passed down your breathing tubes so that the samples can be collected.
An echocardiogram (an ultrasound examination of your heart) may be done if it is suspected that you have developed heart failure.
What are the treatment options for idiopathic pulmonary fibrosis?
At present there is no cure for idiopathic pulmonary fibrosis and the optimal treatment has not yet been found. The aim of treatment is to suppress the symptoms as much as possible.
Because idiopathic pulmonary fibrosis was originally thought to be due to inflammation of the alveoli leading to fibrosis and scarring, treatment has been based on medicines to help suppress (reduce) this inflammation. These included treatments with corticosteroids (steroids) and immunosuppressant medicines such as azathioprine. These medicines are still used to some extent as they can be helpful in some people. Newer medicines are also being studied.
One or more of the following options may be advised to help to improve symptoms, and to slow down the progression of the disease:
- Steroid medication may be tried, usually in combination with immunosuppressant medicines. Previous studies showed that steroid medication improved symptoms in about 1 in 4 affected people. However, some doctors now wonder if these people for whom the steroids worked actually had another type of lung disease. If steroids are prescribed, a high dose is used at first and then reduced to a lower maintenance dose. If there is no improvement after a few months then the steroids are stopped. Some people who take steroids develop side-effects. See separate leaflet called Oral steroids for more details of possible side-effects.
- Immunosuppressant medicines such as azathioprine may also be tried, usually in combination with steroid medication. These also suppress inflammation. Like steroids, they help in just some cases.
- No treatment is another option. Medication can cause serious side-effects in some people. The risk of side-effects has to be balanced with the chance of improving symptoms and slowing down the progression of the disease. No treatment may be advised, particularly for elderly people if their symptoms are mild or are not getting much worse. A chest specialist usually keeps the situation under review.
- Oxygen treatment used in the home may be required if symptoms become severe.
- Pulmonary rehabilitation courses may help some people. The courses include education about idiopathic pulmonary fibrosis and physical exercise, as well as psychological and social support. Ask the chest clinic that you attend about your nearest course.
- Stop smoking if you are a smoker.
- Get immunised against influenza and pneumococcus. They protect against infections that can be particularly severe if you have a disease of the lung.
- A lung transplant may be an option. This is becoming more common, particularly in younger people who develop severe disease despite medication.
Various newer treatments have been tried. These include interferon, N-acetylcysteine and pirfenidone. These newer medicines are thought to work by having an effect on the fibrosis that develops in the disease. However, more trials are needed before the benefit of these medicines can be confirmed.
What is the prognosis (outlook)?
The progression of the disease can vary greatly. Some people respond to medication which may slow the progression of the disease but, in others, it makes little difference. Some people remain stable for many years after being diagnosed, but others deteriorate much more rapidly. It is difficult to predict at the outset how fast the disease will progress for each affected individual. Lung transplantation has been shown to improve survival in those people for whom it is suitable and so is being increasingly used as a treatment. Newer treatments with medicines may also be shown to be of benefit in the future.
Further help & information
Dr Tim Kenny
Dr Gurvinder Rull
Prof Cathy Jackson