Over time, rheumatoid arthritis can lead to lung tissue damage, which can result in a condition called pulmonary fibrosis. With this condition, lung tissue becomes thick and scarred, making it harder to absorb oxygen into the bloodstream.
Rheumatoid arthritis (RA) is an autoimmune inflammatory disorder that causes chronic pain in the joints. RA can also affect other organs, such as the lungs, causing severe breathing problems.
The risk of developing pulmonary fibrosis is higher in people who:
- are frequent smokers
- often come into contact with environmental pollution
- have a family history of pulmonary fibrosis
- regularly use anti-inflammatory medication
Doctors still do not fully understand the link between RA and pulmonary fibrosis, but evidence shows that as many as 40 percent of people with RA have pulmonary fibrosis.
Symptoms of RA vary in type and severity and may come and go.
When the disease is active, it is known as a flare. During a flare, symptoms can vary in duration and intensity.
Common symptoms of RA include:
- morning stiffness that lasts for 30 minutes or longer
- tenderness, pain, or swelling in the joints, lasting 6 weeks or longer
- pain in joints on both sides of the body
- pain in smaller joints, such as the hands, wrists, and feet
When RA leads to lung problems, people may experience the following symptoms:
- shortness of breath
- dry persistent cough
- frequent feeling of tiredness
- sudden, unexplained weight loss
Typically, pulmonary fibrosis and related lung problems develop in people who have lived with RA for several years. This means that doctors usually diagnose RA before pulmonary fibrosis.
However, a study in the journal European Respiratory Review reported that 10 to 20 percent of people experienced symptoms of respiratory problems before they developed typical RA symptoms.
Doctors diagnose RA by asking about a person's medical history, doing a complete physical examination, and ordering a series of imaging and blood tests.
These tests check for:
- swollen joints
- the degree of pain a person is experiencing
- the presence of antibodies in the blood called rheumatoid factor
- bone and joint abnormalities
Common tests to diagnose RA include:
- Erythrocyte sedimentation rate (ESR): A test measuring how quickly red blood cells settle to the bottom of a test tube. The ESR test indicates the presence of an inflammatory condition, such as RA, but cannot diagnose RA on its own.
- C-reactive protein (CRP) test: A test that indicates the level of C-reactive protein in the blood. Higher levels of CRP in the blood may indicate inflammation or infection in the body.
- Complete blood test: A test to check for anemia. A 2017 study in the World Journal of Pharmaceutical and Medical Research reported that 60 percent of Sudanese people with RA in the study also had anemia.
Diagnosing pulmonary fibrosis
A doctor will request one or more of the following tests to help diagnose pulmonary fibrosis.
- pulse oximetry
- pulmonary function test
- imaging tests, such as chest X-rays or computed tomography scans
- lung tissue biopsy
- arterial blood gas test
These tests show whether there is inflammation or damage in the lung tissue. They also measure the levels of oxygen, carbon dioxide, and air capacity in the lungs.
Complications from RA-linked pulmonary fibrosis can become life-threatening if not treated promptly.
According to the National Rheumatoid Arthritis Society, people should see their doctor if they experience lung problems for more than 1 month.
They should also see a doctor if they experience sudden but regular severe breathlessness while doing everyday tasks.
The doctor will assess the extent of the problem and may make a referral to a specialist called a rheumatologist if necessary.
Both RA and pulmonary fibrosis have no cure, so treatment goals aim to manage the symptoms and reduce the progression of the disease.
Medications and treatments to control RA-linked pulmonary fibrosis may include:
RA-linked pulmonary fibrosis progresses differently from person-to-person. Some people experience worsening of symptoms within months, while in others, the disease may take a few years to advance.
Differences in progression may be because age, genetics, and lifestyle factors play a role in the development of both conditions.
According to a study in Clinical Medical Insights: Circulatory, Respiratory and Pulmonary Medicine the average life expectancy for someone with pulmonary fibrosis is 2.5 to 5 years, although this is merely an estimate drawn from large-scale population studies.
If a person has RA and experiences lung problems, they should talk to a doctor at the earliest opportunity about the nature and frequency of symptoms. Recent advances in medication and treatment have improved both management of symptoms and quality of life in the long-term.