New diagnostic criteria for systemic lupus erythematosus (SLE), released by the European and American rheumatology societies, helps to better distinguish patients with lupus from those with primary Sjögren’s syndrome, a study reports.
The study, “New 2019 SLE EULAR/ACR classification criteria are valuable for distinguishing patients with SLE from patients with pSS,” was published in the journal Annals of Rheumatic Disease.
SLE and Sjögren’s syndrome are both systemic autoimmune diseases with shared biological and clinical features, and it’s often difficult to distinguish between the two in clinical practice. In addition, Sjogren’s syndrome can occur alone (primary Sjögren’s) or in association with other autoimmune diseases, most commonly lupus and rheumatoid arthritis.
These guidelines provide a better balance in the specificity and sensitivity of criteria used to diagnose SLE, compared to previous recommendations.
Despite being created specifically for lupus, these guidelines could also be helpful in distinguishing people with SLE from those with another systemic autoimmune disease, such as primary Sjögren’s syndrome, scleroderma, or myositis.
A team of clinicians and researchers at Hopitaux Universitaires Paris Sud, a French reference center for rare systemic autoimmune disorders, evaluated whether the new 2019 SLE EULAR/ACR criteria could outperform older criteria in differentiating between SLE and primary Sjögren’s syndrome patients, and in spotting cases of overlapping disease.
To do this, they measured how many individuals, among three different groups of patients, met the criteria defined for SLE. These groups included 49 people diagnosed with SLE by a clinician, 49 with primary Sjögren’s syndrome, and 26 patients with SLE and SS overlap.
This last group included 13 people with an SLE diagnosis who also had signs of Sjögren’s on a salivary gland biopsy and salivary flow tests. And it included 13 people with a Sjögren’s syndrome diagnosis who were positive for anti-DNA antibodies, a marker of SLE.
The three groups had similar mean disease durations, approximately 14 years.
Nearly all SLE patients (97.9%) but only 4.2% of those with primary Sjögren’s syndrome met the new 2019 SLE EULAR/ACR criteria.
This shows that the 2019 criteria “offered the best equilibrium between specificity and sensitivity compared with the older criteria and was able to discriminate patients with SLE and pSS in clinical practice,” the researchers wrote.
In addition, patients who appeared to have both conditions fulfilled both the criteria for SLE and Sjögren’s syndrome, “confirming the mixed presentation and the capacity of the criteria to detect the overlap,” the team added.
The study also revealed that some clinical and biological signs were more relevant than others in distinguishing SLE from Sjögren’s syndrome.
Patients with SLE more frequently had skin problems, serositis (inflammation of the tissues lining the lungs, heart, and the inner lining of the abdomen), synovitis (inflammation of a type of membrane that lines the joints), kidney disease, low levels of white blood cells (lymphocytes), and generalized inflammation.
Conversely, cough, muscle pain, and blood tests positive for rheumatoid factor at diagnosis were more frequent in those with primary Sjögren’s syndrome.
People with overlaping conditions were more likely to have widespread disease activity than were people with primary Sjögren’s syndrome alone.
Regular checks for dry eyes and dry mouth, known as sicca symptoms, is easy and can also help to differentiate the two conditions, the researchers said.
Taken together, the findings show that the “new 2019 SLE EULAR/ACR criteria for SLE can be useful in clinical practice, helping to differentiate between SLE and [primary Sjögren’s syndrome] and detecting overlap presentations,” the researchers concluded.