Felty's syndrome is a rare disease that affects the body’s ability to fight infection. Whilst it is sometimes a complication of rheumatoid arthritis, the exact cause remains unknown.
We spoke with leading rheumatologist, Dr Gerald Coakley, to find out how Felty’s syndrome is diagnosed as well as what treatment options and lifestyle changes can help to relieve symptoms.
What is Felty's syndrome?
Felty’s syndrome is an uncommon complication of rheumatoid arthritis, first described by the American Physician A.R. Felty. The most important aspect of the condition is a low neutrophil count. Neutrophils are one of several types of white cell that circulate in the blood and are key to preventing and fighting bacterial infections. In 1924, Felty described five patients with rheumatoid arthritis, a low neutrophil count and an enlarged spleen (an organ in the left upper abdomen that is important in the healthy function of the immune system). It affects around 1% of people with rheumatoid arthritis.
What are the symptoms of Felty's syndrome?
The condition affects about twice as many females with rheumatoid arthritis as males, and usually develops 10 - 20 years after the onset of arthritis. So, most people who develop Felty’s syndrome are in their 50s or older. Other common features include rheumatoid nodules, weight loss, or Sjögren’s syndrome, giving rise to dry eyes and dry mouth. About one third of patients suffer from leg ulcers caused by skin vasculitis, or interstitial lung disease (fibrotic, scarring disease of the lung), singly or in combination.
How is Felty’s syndrome diagnosed?
Felty’s syndrome is first suspected when a patient with known rheumatoid arthritis develops a persistently low neutrophil count. This feature can be caused by many other conditions apart from Felty’s syndrome, including some of the therapies commonly used to treat rheumatoid arthritis (like Methotrexate, Leflunomide or Sulfasalazine), and several types of bone marrow disease.
The first step is usually to stop any medication that might be responsible for causing a low neutrophil count (a lot of treatments for rheumatoid arthritis can in fact cause a low count). If the count recovers, it usually means the medication was causing the problem and a switch to another treatment is a sensible step. If the count remains low, we usually arrange an abdominal ultrasound scan to look for an enlarged spleen, and refer to a haematologist (blood specialist) who will carry out a bone marrow biopsy. This gives us an accurate picture of the health of the bone marrow, and helps to exclude other serious causes of a low neutrophil count apart from Felty’s syndrome.
If it is shown that a drug is not responsible and the bone marrow shows no other cause of a low neutrophil count in a patient with proven rheumatoid arthritis, then that confirms the diagnosis of Felty’s syndrome. Most, but not all, patients will have an enlarged spleen.
How is Felty’s syndrome treated?
Felty’s syndrome has always been quite a rare disease, and it has become rarer still as our treatment of rheumatoid arthritis has become more effective in the last 20 years. That’s a great sign of progress, but it does mean that the usual way scientists use to work out what treatments work (the randomised controlled trial) is more or less impossible. Few rheumatologists will ever see more than a handful of Felty’s syndrome patients in their careers, so we do not have a strong evidence base for treatment decisions.
From the imperfect research literature we have, the most effective treatment is Methotrexate. This is the treatment of choice for rheumatoid arthritis, but it can also cause a low white cell count. In Felty’s syndrome, we advise giving much lower than usual doses of the drug, with careful monitoring and review. In around 50% of cases, the white cell count will return to normal, but it may take a few months for this to happen. For those whose condition is responsive to Methotrexate, it is vital not to stop it for long (for example when recovering from an infection or surgery) because the white cell count can crash down again very quickly without Methotrexate.
When Methotrexate does not work, there are several other options but these are best discussed with a specialist because decision-making is complicated and depends on the individual characteristics of the patient.
Are there lifestyle changes that can help the condition?
The main risk with Felty’s syndrome comes from infections. Therefore, it is important to adopt as healthy a lifestyle as possible to reduce the risk of picking up infections. That means taking regular exercise, not smoking, and maintaining a healthy weight. Having a nutritious diet and managing stress in a healthy way is also key. It is really important to make use of all available health protection strategies too, like getting an annual flu vaccination and having the Pneumovax (Pneumococcal pneumonia vaccination) once every 10 years.
For more guidance on treating Felty’s syndrome you may like to book an appointment with a leading rheumatologist such as Dr Gerald Coakley. Visit Dr Coakley’s Top Doctors profile today for more information.