Interstitial lung disease (ILD) comprises of a group of several diseases
of different causes but similar features. It is classified as either Primary
(or idiopathic) and Secondary (Secondary to some other disease). Secondary ILD
commonly occurs in patients with pre-existing diseases such as rheumatoid
arthritis, systemic sclerosis, sarcoidosis and occupational disorders.
Hypersensitivity pneumonitis is a group of common ILDs which occur on exposure
to organic dusts which happens during farming, keeping birds, manufacturing
cheese, air-conditioning etc. ILD can also develop following viral infections,
administration of certain drugs, high-dose radiation and radiotherapy.
Primary or idiopathic ILD is the more
serious type whose cause is not identifiable. Of various kinds of idiopathic
ILDs, idiopathic pulmonary fibrosis (IPF) is most important. There are a few
other types of idiopathic ILDs importantly, non-specific interstitial pneumonia
(NSIP), organizing pneumonias (OP), desquamative interstitial pneumonia and
acute interstitial pneumonia.
Common
complaints
1.
Breathlessness especially on
exertion. Patient may feel completely fine at rest.
2.
Dry cough which is quite hacking
and troublesome, often not relieved with routine cough suppressants.
3.
Generalized weakness, malaise,
fatigue and tiredness.
4.
Loss of appetite.
5.
Weight loss.
6.
Blueness of fingers and nails
during exercise.
7.
Symptoms of underlying disease
such as joint pains, skin rashes or other manifestations.
Investigations
required for confirmation of diagnosis
1.
Routine blood tests:
hematological, biochemical and immunological as considered important
by the physician.
2.
Chest X-Ray
3.
Pulmonary function tests –
spirometry. Sometimes, blood gases assessment.
4.
High resolution CT Chest
5.
ECG and Echocardiography
6.
Fiberoptic bronchoscopy and
lung biopsy as decided by the physician.
7.
Occasionally, lung biopsy with
thoracoscopy or open surgery is required to establish the diagnosis.
Other tests may be required for identification and exclusion
of a secondary cause of ILD such as for rheumatoid arthritis, sarcoidosis,
occupational disorder or hypersensitivity pneumonitis. Serological tests may be
required for hypersensitivity pneumonias.
Treatment of ILD
There is no efficacious therapy for ILDs.
Treatment of IPF remains elusive. Patients and clinicians are faced with four
options: (i) no treatment, (ii) corticosteroids and cytotoxic agents, (iii)
anti-fibrotic drugs, (iv) other miscellaneous agents.
Based on the evidence available
immunosuppression with corticosteroids and cytotoxic agents is not helpful for
IPF. These drugs are helpful in secondary ILDs such as CTD associated ILD,
sarcoidosis and some other forms of IIP (NSIP, COP and DIP). Pirfenidone is the
one agent which may provide some benefit in IPF. It is an anti-fibrotic drug
which is shown to decrease the decline in lung function parameters. Several
other drugs are also employed, but not very useful in improving the condition.
Most patients with IPF continue to experience an inexorable progression
to death, with lung transplantation being the only measure shown to prolong
survival. Currently, lung transplantation has been associated with improved
lung function, exercise capacity, quality of life, and survival in this group
of patients. The treatment is available at very few centres in India and the
cost is prohibitive. Most importantly, there is very limited availability of
organs. Lungs for transplantation can be
retrieved only from a brain-dead individual with fully informed consent of the
family following compliance of all the requisite legal and medical guidelines.
Thus, the primary objectives of treatment in IPF are essentially to
provide symptomatic relief of symptoms, oxygen therapy for desaturation and
pulmonary rehabilitation. One also needs to treat the complications which occur
either secondary to the disease per se, or the toxicity of drugs.
Prognosis
Natural history of ILD
Most forms of ILDs are progressive in nature. There is no permanent
cure. Patient’s condition is likely to deteriorate with time. IPF is the worst
form of ILD which carries a poor prognosis with an average survival of 3-5
years. Other ILDs have variable natural history which is modifiable with
treatment.
_____________________________________________
Dr Surinder K. Jindal, MD, FCCP, FAMS, FNCCP
(Ex-Professor & Head, Department of Pulmonary Medicine
Postgrad Instt of Med Edu & Res, Chandigarh, India)
Medical Director, Jindal Clinics, SCO 21, Dakshin Marg, Sector 20 D,
Near Guru Ravi Das Bhawan, Chandigarh, India 160020.
Ph. Clincis: +91 172 4911000
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