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Certain children with pediatric acute-onset neuropsychiatric syndrome are at higher risk for autoimmune diseases, such as arthritis.

Some children with pediatric acute-onset neuropsychiatric syndrome (PANS) show signs of immune activation and vasculopathy during psychiatric flares and have an increased risk for other autoimmune diseases, according to a study published online in JAMA Network Open.

“We observed an unexpectedly high frequency of immune activation signs, arthritis, and autoimmune disease, suggesting that PANS itself is part of an inflammatory diathesis, akin to neuropsychiatric lupus or Sydenham chorea, where neuroinflammation is comorbid with arthritis and other inflammatory signs,” Jennifer Frankovich, MD, and colleagues wrote.

The retrospective study included 193 children diagnosed with PANS at a mean age of 7.5 years. The researchers reviewed electronic medical record histories, collateral records, and parent-response questionnaires to pull data on laboratory test results, diagnoses, physical examination results, and findings from musculoskeletal imaging. They were particularly interested in immune activation markers measured during psychiatric symptom flares as well as features and imaging findings of arthritis and other autoimmune diseases.

Patients were followed up for an average of 4 years.

Estimated Incidence of Arthritis More Than 25% By Age 14

Among patients who underwent immune marker testing, 77.2% had at least one sign of autoimmunity, immune dysregulation or inflammation, or vasculopathy during a flare, according to the study results. Specifically, 54.2% had nonspecific markers of autoimmunity, 12.0% had nonspecific signs of immune dysregulation or inflammation, and 35.8% had signs of vasculopathy.

By the age of 14 years, the estimated cumulative incidence of arthritis among patients was 28.3%. The estimated cumulative incidence of an additional autoimmune disease was 7.5%. The mean age at the time of arthritis diagnosis was 12.7 years, the study found. The mean age at the time of an autoimmune diagnosis other than arthritis was 12.4 years.

Among patients with arthritis, novel findings included joint capsule thickening in 55.0%, distal interphalangeal joint tenderness in 81.8%, and spinous process tenderness in 80.0%. The most common arthritis subtypes were enthesitis-related arthritis (67.3%), spondyloarthritis (49.1%), and psoriatic arthritis (18.2%).

“Addressing inflammation may be critical in preventing the development of arthritis and other autoimmune diseases, but clinical trials are needed to determine the association of anti-inflammatories with psychiatric symptoms in this patient population,” the researchers wrote.