Sjogren's is Common

KEY POINTS: 

Sjogren’s is not rare, just rarely diagnosed 

  1. Sjogren’s is common, impacting about 1 % of the U.S. population.

  2. Sjogren’s is more than dryness.It is a serious multi-systemic disease, related to rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE).

  3. Despite being common and serious, many clinicians remain unfamiliar with Sjogren’s. This contributes to delayed diagnosis, misdiagnosis and suboptimal care.

How common is Sjogren’s?

 

The best estimate we have, based on the National Arthritis Data Workgroup (NADW), shows that about 1% of the U.S. population has Sjogren’s. This makes Sjogren’s the second most common autoimmune rheumatologic disease, after RA. Its closest biologic cousin is SLE (123).  Although far more common than SLE, few lay people have heard of Sjogren’s, and clinicians tend to overlook and downplay the disease.

Sjogren’s prevalence is even higher for women because they comprise 90 -95 % of cases. While lower for men, it is still significant. The number of children impacted by Sjogren’s is unknown, but pediatric cases have been increasingly recognized in recent years.  

It is hard to pin down precise numbers because large population-based studies have not been done. Sjogren’s prevalence will be easier to determine when researchers identify novel biomarkers that can diagnose Sjogren’s early and accurately.

Why do some doctors continue to say that Sjogren’s is rare?

Research articles quote a wide range of Sjogren’s prevalence:  0.02 % to 4 %. Prevalence can be thought of as a snapshot of the number of people in a population living with a disease. Because Sjogren’s does not go away, the prevalence is highest in older populations. 

Lowball estimates of prevalence are usually obtained by counting the number of patients enrolled in Sjogren’s disease registries. Many patients are not included in registries because this requires clinician awareness and interest to diagnose and report Sjogren’s cases voluntarily. Registries generally use strict criteria for inclusion such as requiring a positive SSA. They usually exclude people with “associated Sjogren’s,” about half of all Sjogren’s cases.   

The main reason for low disease estimates is the profound under-diagnosis of Sjogren’s.

Undiagnosed:

Who are the missing Sjogren’s patients? 

​Sjogren’s is typically diagnosed in women in their 40s and 50s. Yet many of these patients remember Sjogren’s symptoms that started in their 20s and 30s, or even during childhood (115).  Younger patients often have milder symptoms and incomplete presentations. Few clinicians consider a Sjogren’s diagnosis in people under age 40. It typically takes years of progression before anyone realizes that the seemingly disparate symptoms could all be related. It is quite common for the patients themselves to connect the dots and request an evaluation for Sjogren’s.

1. Younger patients

Patient Story

It took me 5 to 6 years and THIRTEEN specialists to get a diagnosis.

A neurologist finally diagnosed me.

2. Patients with poor access to medical care

In the U.S., health care costs are a major barrier to care. Gender, age, racial, and class bias may also factor in. The lack of clinicians who are knowledgeable about Sjogren’s is a major problem worldwide.  

Patient Quote, 2020

I need advice on finding a GP who thinks Sjogren’s is real!

Many patients have been told by a rheumatologist that they cannot have Sjogren’s without testing positive for SSA. This is simply incorrect! Thirty to forty percent of Sjogren's patients are negative for SSA.

3. Seronegative (SSA negative) patients

Some rheumatologists stick rigidly to the Classification Criteria for making a diagnosis. Rheumatologists sometimes fail to account for the limited accuracy of tests, as well as the over-emphasis on sicca features in the Classification Criteria( 36, 77). Ultimately, Sjogren's is a clinical diagnosis, based on expert opinion (2). The problem is that there are few experts!  

Some sicca-dominant patients are diagnosed for years as “sicca syndrome” or “keratoconjunctivitis sicca (KCS)”. An average of 10 years passes from the time a patient is diagnosed with dry eye disease until diagnosis with Sjogren’s (35). Sicca patients are rarely asked about systemic symptoms by dentists and eye doctors. This information could help lead to a Sjogren’s diagnosis.

5. Very predominant sicca manifestations

4. Patients who do not meet the current Classification Criteria

Thanks to the Sjogren’s Foundation, the new ICD 10 billing codes now emphasize the distinct difference between Sjogren’s and sicca syndrome.

6. Patients with non-sicca presentations

Twenty percent of patients present without obvious sicca, including about half of those with early/ predominant neurologic manifestations (32). Organ system involvement or lymphoma may be the first sign of Sjogren’s (2, 3, 97).

Patient Story

 

I had been for advocating for years that my lung problems, which started in childhood, were part of a systemic disease.  But no one was listening.

My first rheumatologist said that it couldn’t possibly be Sjogren’s because none of the classic Sjogren’s blood tests came back positive. He reluctantly agreed to send me to a specialist for dry mouth. She suspected Sjogren’s immediately and ordered a lip biopsy which was positive, and eventually moved me to a knowledgeable ophthalmologist who quickly confirmed the Sjogren’s diagnosis.

 

The onset of my symptoms occurred 32 years before my initial Sjogren’s diagnosis and after that, another two-plus years for a lung diagnosis. I went through 7 lung doctors to find one that finally, correctly, diagnosed my lung problems as Sjogren’s complications. 

~ Patient with debilitating Sjogren’s lung disease

7. Patients misdiagnosed as having another connective tissue disease (CTD)

Common misdiagnoses include RA and SLE (23). This often happens with patients who have inflammatory arthritis or organ system involvement, simply due to the lack of understanding that these may also occur in Sjogren’s.

8.  Patients with associated Sjogren’s  (“Secondary Sjogren’s”)

About half of Sjogren’s cases occur together with another major connective tissue disease. This is now known as "Associated Sjogren’s" but often referred to by the outdated term, “secondary."  Associated Sjogren's appears to have the same disease manifestations as Sjogren’s alone (“primary”) (122, 123). In this situation, Sjogren’s is often overlooked and unaddressed.

The problem with the term “Secondary Sjogren’s”   

Even Sjogren’s researchers define the term “secondary” in multiple ways. “Secondary Sjogren’s” is an outmoded, inaccurate term. All forms of Sjogren's deserve to be studied and treated. At this time, Sjogren's experts recommend the same monitoring and treatment, regardless of whether Sjogren's occurs alone or in in association with another connective tissue disease.

 

It is inaccurate to say “Sjogren’s secondary to lupus” or that Sjogren’s “turns into lupus” as some patients are told. This is a holdover from the distant past, when Sjogren’s was sometimes thought to be a milder form of lupus.

9.  Patients with classic Sjogren’s features (a surprisingly large group of undiagnosed patients)

A population-based study of the prevalence of Sjogren's in Spain (2020) estimated a 50% undiagnosed rate, based on telephone screening followed by a rheumatology visit for patients with sicca symptoms or recurrent salivary gland swelling. (141) Because the screening was based on a limited spectrum of disease and did not include non-sicca presentations, even this 50% is likely to be an underestimate of the number of undiagnosed patients. 

 

Failure to teach clinicians about Sjogren’s contributes to long delays in diagnosis and suboptimal care. The disease is simply not on their radar. For a sobering look at this problem, please see the blog series, Sjogren's Neglect I-IV.  

It is likely that many patients live an entire lifetime undiagnosed and ill, being given labels such as fibromyalgia, depression, health anxiety (aka hypochondria), and “severe menopause.”

When will Sjogren’s patients start getting acceptable, or even adequate, care? 

This will happen when:

  • Better tests and treatments are discovered by researchers. Clinicians are more likely to pay attention to Sjogren’s when they have better tools.

  • Medical education reflects the current understanding of Sjogren’s. Sjogren’s is common, serious and always systemic. Too many clinicians still dismiss Sjogren’s as a rare, nuisance dryness disease that is not life-altering and potentially life-threatening if left unaddressed.

  • Rheumatology leadership steps up to the plate to promote up-to-date Sjogren’s education, comprehensive management, and Clinical Practice Guidelines.

Updated 7-18-20