Physicians diagnose early onset primary Sjögren’s syndrome in patients younger than 35 years old. Previous studies have found these patients have a higher prevalence of adenopathy, rheumatoid factor (RF) positivity, anti-Sjögren’s-syndrome-related antigen A (anti-SSA) antibodies and monoclonal immunoglobulin. Pediatric onset of primary Sjögren’s syndrome, although rare, is associated with many of these same features. Previous studies have also found patients with a European League Against Rheumatism (EULAR) Sjögren’s Syndrome Disease Activity Index (ESSDAI) score of 5 or more are more likely to develop lymphoproliferative disease.
Recent research has now connected previous studies, building a picture of patients with early onset primary Sjögren’s syndrome who are more likely to have a specific phenotype with clinical and biological features known to be predictive factors of severe systematic disease. Celine Anquetil, MD, of CHU Claude Huriez, France, and colleagues found a different evolution of ESSDAI score based on the age of disease onset, indicating patients with early-onset disease are more likely to worsen over time. They reported their findings online in Rheumatology.1
The study evaluated 55 patients with early onset disease and compared them with 338 patients who were diagnosed with primary Sjögren’s syndrome after the age of 35. The mean duration of symptoms in the population was five years in the cohort, seven years in the early onset group and five years in the later onset group. The investigators compared the cumulative features of the patients according to their age at diagnosis.
“In this study, we were able to identify Sjögren’s syndrome-specific features that were associated with the patient’s age at diagnosis of the disease,” write the authors in their discussion. “Early onset disease was associated with a higher frequency of salivary gland enlargement, adenopathy, purpura, renal involvement, ANA [antinuclear antibodies] (especially anti-SSA and anti-SSB antibodies), RF positivity, low C3 and C4 levels and hypergammaglobulinaemia. Of note, the onset of symptoms is very difficult to assess in primary Sjögren’s syndrome.”
Researchers found no significant difference between early and later onset patients regarding C-reactive protein (CRP) level, lymphocyte count or cryoglobulinemia. When the investigators evaluated salivary gland enlargement, adenopathy, purpura, anti-SSA antibodies and low C3 level in a multivariate analysis, they found only anti-SSA antibodies remained statistically associated with early onset primary Sjögren’s syndrome.
At baseline, the investigators found no significant difference between the ESSDAI scores of patients with early onset diseased compared with those with later onset. However, they did find a significantly different change in ESSDAI scores between baseline and five-year follow up in these patients relative to controls (P<0.005). Moreover, researchers noticed a trend for worsening in the early onset group and significant improvement in the later onset group. These new data suggest a specific phenotype may correspond to early onset disease that is consistent with severe systemic disease and development of lymphoproliferative disease.