medwireNews: People who develop early-onset primary Sjögren’s syndrome (pSS) have “strikingly more severe disease activity” and greater activation of the cellular immune system compared with those diagnosed at a later age, researchers report.
Therefore, people with early-onset disease “require more positive treatment with glucocorticoids and/or immunosuppressants and merit closer follow-up and regular monitoring,” say Zhang Fengxiao (Hebei Medical University, Shijiazhuang, China) and colleagues in Rheumatology.
Their study included 333 people who were newly diagnosed with pSS at the Hebei General Hospital in 2016–2019, of whom 10.81% were aged 35 years or younger and categorized as having early-onset pSS.
These 36 people had significantly higher baseline scores on the 2010 EULAR SS Disease Activity Index (ESSDAI) than the 297 individuals with later-onset disease, at a median of 11 versus 7 points, and were also significantly more likely to have moderate (ESSDAI=5–13) or high (ESSDAI ≥14) disease activity, at rates of 52.78% versus 46.46% and 36.11% versus 23.23%, respectively.
Rates of hematologic (80.56 vs 52.53%), mucocutaneous (50.00 vs 22.56%), and renal (19.44 vs 5.05%) involvement were also significantly higher in the early- than later-onset group.
In accordance with the higher degree of disease severity, patients with early-onset pSS were prescribed prednisone/methylprednisolone (38.89 vs 21.55%) or mycophenolate mofetil (13.89 vs 0.34%) significantly more often than those in the later-onset group. After an average follow-up of approximately 30 months, the median ESSDAI score was reduced to 6 points in the early-onset group, but remained significantly higher than that in the later-onset group, at 5 points.
The team also evaluated immunologic profiles in blood samples from the two groups, finding that people with early-onset pSS were significantly more likely than those in the later-onset group to have elevated serum immunoglobulin G levels (77.14 vs 31.16%), low complement C3 (41.67 vs 20.20%) or C4 (27.78 vs 6.40%) levels, anti-Ro/SSA positivity (91.67 vs 51.85%), and anti-La/SSB positivity (50.00 vs 20.54%) at the time of diagnosis.
People in the early-onset group also had significantly lower numbers of CD16/CD56+ natural killer cells than those with later-onset disease, but CD3+ T cell and CD19+ B cell counts were comparable between the groups.
These findings indicate “greater activation of the cellular immune system” in people with early-onset pSS, say the researchers.
They also note that a numerically higher proportion of patients in the early- versus later-onset group developed systemic lupus erythematosus (SLE) during follow-up (2.78 vs 1.74%). Although this difference did not reach statistical significance, the study authors suggest that people with early-onset pSS “should be monitored regularly because of their potential to develop SLE.”
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