So what is Sjogren's, really?
Updated: Dec 28, 2022
Sjogren’s is called an autoimmune rheumatic disease (AIRD).
This is a useful label because Sjogren’s is closely related to other AIRDs such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and systemic sclerosis (SSc). These four diseases have overlapping features, comorbidities, and autoantibodies. While a large majority of patients with RA, SLE, and SSc have autoantibodies, occasionally they do not. On the other hand, about 30-40% of Sjogren’s patients do not test positive for SS-A, the autoantibody that is used to support a Sjogren’s diagnosis (6).
Does this mean Sjogren’s is always autoimmune?
You may be surprised to find out that there is no clear answer to this. “Autoimmune” actually means something more specific than the “the body attacking itself”. Autoimmune diseases are associated with autoantibodies. Calling Sjogren’s an “autoimmune disease” is oversimplified, but works well in most circumstances.
The “autoimmune” label can become a problem if your rheumatologist won’t diagnose you or treat you for Sjogren’s because your “blood tests don’t show it”. They may say that autoantibodies, especially SS-A, must be present to have the disease. However, SS-A negative (seronegative) Sjogren’s is quite common. Other autoantibodies may be seen in Sjogren's. More research is needed to understand the pathways that lead to Sjogren's disease, and how they may differ in different groups of patients.
SS-A is not specific to Sjogren’s. It is often present alongside other rheumatic diseases such as SLE and SSc (166). SS-A is sometimes found in people with infections such as hepatitis C and COVID-19. Some healthy people carry SS-A and never develop Sjogren’s (14). Clearly, we need better tests! Sjogren’s is a complex disease. What drives the immune system to mistakenly attack the body is still not completely understood. Autoantibodies serve as helpful biomarkers (indicators) for diagnosis when patients have them. In Sjogren’s, the role of autoantibodies in the disease process remains unclear (166).
The “autoimmune” label may get in the way of Sjogren’s care if
Your rheumatologist won’t diagnose you with Sjogren’s because you don’t have autoantibodies, especially SS-A. Myth buster: Many people (30% or more) with Sjogren’s don’t have SS-A or other autoantibodies such as SS-B, ANA or RF that are typically associated with Sjogren’s.
Your SS-A was positive but turns negative on a follow-up test. As a result, your rheumatologist tells you that you no longer have Sjogren’s. Myth buster: Sjogren’s does not go away. If you have clinical features of Sjogren's, once you test positive for SS-A, it is not recommended to repeat the test because this changes may be misinterpreted. SS-A titers do not go up and down with disease activity. Sometimes SS-A disappears. This does not mean Sjogren's is better or no longer present.
Your rheumatologist does not monitor or treat you for Sjogren’s because you don’t have autoantibodies such as SS-A. Some clinicians think that Sjogren’s patients without SS-A don’t develop serious systemic features. Myth buster: While SS-A is a risk factor for certain complications and comorbidities, patients without SS-A may also develop serious Sjogren’s complications. Some complications are more common in SS-A positive patients, while others are more common in SS-A negative patients. Every Sjogren’s patient deserves the full range of monitoring and treatment, regardless of SS-A status (139).
See this blog post to learn more about "seropositive" vs "seronegative" Sjogren's.
Sjogren’s may be both autoimmune and autoinflammatory.
Sjogren’s is a chronic systemic inflammatory disease. It is never just a sicca disease.
Sjogren’s is an immune-mediated disease. It might be both autoimmune and autoinflammatory. Subtypes of Sjogren’s may involve different immune system pathways that lead to the same disease (168).
From the Spondylitis Association website
Simple definitions
Immune-mediated disease- a disease that is caused when a malfunctioning immune system attacks the body. Autoimmune and autoinflammatory diseases are types of immune-mediated diseases. Many immune-mediated diseases, including Sjogren’s, are rheumatologic. Others, such as multiple sclerosis, are not rheumatologic.
Autoimmune disease- an immune-mediated disease associated with autoantibodies. Examples: SLE, myasthenia gravis, celiac disease.
Autoinflammatory disease- an immune-mediated disease with no associated autoantibodies. Examples: Crohn’s disease, spondylitis, psoriasis.
Many of the medical terms on this page have been added to the Glossary. The link to the Glossary is located in the footer (the bottom) of every page.
