Secondary Sjögren’s Syndrome and RA
Sjögren’s syndrome (pronounced SHOW-grens), like RA, is an autoimmune disorder in which the body’s immune system attacks its own healthy tissue. In Sjögren’s syndrome, the immune system attacks various organs, but principally the glands that produce tears and saliva. These glands are called lacrimal glands (from the Latin word lacrima for tears) and salivary (meaning saliva-producing) glands. The damage that occurs to these glands in Sjögren’s syndrome leads to a decrease in the volume of secretions (tears or saliva) and a change in their quality. This results in the symptoms that characterize the disorder, including dry eyes or mouth. Dryness affecting the eyes is sometimes referred to as keratoconjunctivitis sicca (KCS, for short) and dryness affecting the mouth is sometimes referred to as xerostomia.
Sjögren’s syndrome, with both eye (KCS) and mouth (xerostomia) symptoms, can be a complication of RA. When it occurs with RA, the condition is said to be secondary to RA and is called secondary Sjögren’s syndrome. Studies have estimated that secondary Sjögren’s syndrome in cases that fulfill diagnostic criteria affects from 4% to 31% of patients with RA and that 30% to 50% of RA patients may have dry eye or mouth features that do not meet the criteria for diagnosis.1,2
One study found that RA patients with secondary Sjögren’s syndrome had distinct features that set them apart from those with RA alone. They tended to have higher RA disease activity as measured by disease activity scores (DAS) and more severe arthritis, with a greater number of swollen, tender, and deformed joints. They also tended to be older and have a longer duration of RA. Patients with RA and secondary Sjögren’s syndrome appeared to have stronger hereditary component to their disease, with a clearer history of autoimmune disease in their family. Patients with RA and secondary Sjögren’s syndrome had a distinct profile in terms of presence of certain antibodies, with patients with both diseases tending to be rheumatoid factor (RF)-positive, as well as positive for other auto-antibodies (SSA and SSB). Patients with the RA and Sjögren’s combination were also more likely to have blood abnormalities, including decreased numbers of platelets (thrombocytopenia) and decreased numbers of red blood cells (anemia). Interstitial lung disease, a common lung complication associated with RA, was also more likely to be found in RA patients with secondary Sjögren’s syndrome.1
Diagnosis and treatment of Sjögren’s syndrome
Sjögren’s syndrome is diagnosed using eye and mouth tests including the Schirmer test, which measures function of the lacrimal (tear) glands; the slit lamp examination, which is used to determine the dryness of the eye; tests involving use of stains to measure damage to the eye surface; a mouth exam; and lip biopsy. Additionally, blood tests may be used to determine levels of immune system chemicals or markers, the presence of which suggest Sjögren’s syndrome.
Treatment for Sjögren’s syndrome may vary from patient to patient, but will typically involve relief of dryness symptoms using artificial tear products or medications that stimulate saliva production. In Sjögren’s syndrome that is secondary to RA, non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, corticosteroids, and immune-modifying drugs such as methotrexate, may be used to address immune system dysfunction.