The effects of RA on the lungs
Rheumatoid arthritis (RA) is a generalized disorder which can affect virtually any organ of the body. Although most patients are aware of its effects on the joints, fewer may recognise its potential for causing lung disease. However, after heart disease, lung disease is the second commonest cause of death in RA and interstitial lung disease (ILD) was the only internal organ disorder found to have increased in frequency among RA patients in a recent large survey. Now that many patients are able to get around more easily with effective treatment of their joint disease, some are noticing that they are limited by breathlessness. This article will deal with the common forms of lung disease found in RA, the risk of pneumonia in RA, and the good and bad effect of drugs on the lung in RA.
Forms of lung disease in RA
The lungs are accessed by the airways which can themselves become inflamed in RA, causing a dry cough and breathlessness. This is quite common and is more frequently found in smokers, especially if they have dryness of the eyes and mouth (secondary Sjogren’s syndrome). The condition is a little like asthma and may respond to steroid inhalers. The condition is rarely serious or rapidly progressive.
The airways lead to the alveoli which are small air sacs where oxygen is absorbed into the body’s bloodstream. Changes in the structure of the lung at this level can result from inflammation leading to fibrosis, with destruction of the lung tissue. This is often called pulmonary fibrosis in laymen’s terms or interstitial lung disease (ILD) and may cause cough, breathlessness and fatigue as oxygen levels fall. Interstitial means the air spaces which is where oxygen is absorbed into the blood. This condition has been found in up to a quarter of all patients with RA using lung scans although many patients are not aware of any related symptoms, and only a minority develop progressive problems. Factors increasing the likelihood of developing ILD include:
- male sex
- having RA a long time and the presence of other systemic features
- Blood tests may also be useful in that patients who are positive for rheumatoid factor and a related test called CCP also appear to be at increased risk
- Breathing tests can be used to assess severity and, where needed, response to therapy.Treatment of this condition is dealt with in the final section.
Other forms of lung disease have become much rarer in RA with fluid around the outside of the lung (pleural effusions) and nodules within the lung both much less common than previously, probably as a result of the earlier and more effective treatment of RA.
Patients should seek help from their doctor if they have progressive (for over a month) or sudden severe breathlessness limiting everyday tasks. Investigations are likely to include a chest x-ray, blowing tests and possibly a lung scan.
The risk of pneumonia
The risk of lung infection is generally agreed to be about twice that seen in patients without RA. Research has shown that this relates to the activity of the disease itself, as well as to the use of certain drugs such as oral steroids .This risk may be reduced by ensuring that patients receive annual influenza jabs and at least a single pneumonia vaccination. This advice would seem to be important for all patients with RA, independent of their treatment.Some doctors recommend that drugs such as methotrexate should be suspended during an infection requiring antibiotic therapy. There is no doubt that smoking increases the risk of developing RA, increases the risk of getting pneumonia and reduces the chances of responding to treatment. All patients with RA should be actively encouraged and supported to stop smoking.
The presence of chronic infection in the lungs (bronchiectasis) is now known to be increased significantly. This is important as it causes progressive productive cough and can be associated with poor outlook joint disease. Treatment options are presently being explored for the treatment of both lung and joint problems in this setting.
The effects of drugs on the lung
Certain drugs used in the treatment of RA can have a potentially bad effect on the lung. Methotrexate can cause an acute lung inflammation called pneumonitis but this is thought to occur in under 1% of users. It can occur in patients with normal lungs but those with existing lung disease such as ILD do appear to be at higher risk.
The biologic agents have a complex effect on the lung with some appearing to worsen the outcome of established ILD while others may improve symptoms. Specifically, the anti TNF drugs such as etanercept, infliximab and adalimumab have all been reported to worsen ILD in some cases and many doctors are wary of using these agents in patients who are already breathless as a result of this.
By contrast, the use of the anti-B cell drug rituximab, advocated by NICE for patients who fail anti-TNF drugs, may be associated with stabilization or even improvement in some patients with ILD (16), and there is subjective evidence that the same drug may be effective in treating those RA patients who have bronchiectasis.
Other established drugs in the treatment of ILD in RA did include steroids and azathioprine. However their role has been called in to question with the results of a recent study of ILD in patients without RA, where they were found to be ineffective. By contrast, cyclophosphamide is still effective in many patients with severe disease although side effects can occur. Newer drugs such as mycophenolate have been recently found to help some patients with RA-ILD, and appear more effective and safer than previous agents .There does appear to be evidence that the outcome of RA patients with lung disease has improved recently, and the hope is that this aspect of RA will also soon start to come under control with effective therapy. As with all other aspects of RA, a good and varied diet and regular exercise is to be commended.
References available on request
Dr Clive Kelly MD FRCP Consultant Physician, Department of Rheumatological Medicine, Queen Elizabeth Hospital
Original article: 15/09/2011
Next review due: 13/08/2017