One-year delay in diagnosis common for Down syndrome arthropathy

Patients with Down syndrome arthropathy experience a year-long delay from symptom onset to diagnosis, according to a presentation at the 2019 ACR/ARP Annual Meeting.

“We have found that there is a high incidence of these children with Down Syndrome who are presenting with arthritis,” Jordan T. Jones, DO, MS, assistant professor of pediatrics at the University of Missouri-Kansas City School of Medicine, said during a press conference. “It does seem to be more predominantly small joints and more aggressive in onset with more erosive disease when it presents, with many joints being affected.”

“The other important thing that we see in these children is that there is a really big delay from the time of symptom onset to the time of diagnosis,” Jones said. “Obvious reasons [include] symptoms are not being well described, and these children present with a lot of motor function delays that can be passed off as typical of down syndrome development, even though that might not be the case.”

To illustrate the clinical manifestations unique to arthropathy patients with Down syndrome, Jones and colleagues used the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry to identify children with juvenile idiopathic arthritis (n= 7,337) for whom Down syndrome was documented as a coexisting condition (n=36). From this cohort, the researchers collected data included demographics, disease characteristics, laboratory results and treatment exposure.

According to study results, among patients with Down syndrome arthropathy, the average age of onset for musculoskeletal symptoms was 7.1 years with an average delay of 11.5 months to diagnosis for JIA.

“In the vast majority [of patients] presenting with polyarticular disease, there was an almost one-year delay from symptom onset to diagnosis, which is improved from the literature, but is still a very long time between the symptoms and the diagnosis,” Jones said.

The researchers also found that, at patient diagnosis, 64% presented with polyarticular, rheumatoid factor-negative disease and 39% reported morning stiffness with an average of four active and four limited joints. Additionally, 22% of patients exhibited elevated inflammatory markers, while 33% were positive for ANA and 17% were positive for HLA-B27.

Jones and colleagues also noted that 64% of patients were prescribed a DMARD at diagnosis, 36% of whom were simultaneously prescribed a biologic. During the course of disease, 78% of patients had been prescribed a DMARD, including methotrexate, and 75% had been prescribed a biologic.

“Even when these medications were started early and were more aggressive, these kids still are not responding well to that,” Jones said. “Whenever they are started on methotrexate, almost half of them have to discontinue that medication because of the adverse effects or toxicity. Interesting, even though about half of them stopped that medication because of those side effects, about half continued on that medication which might indicate that there is still a place for that medication in treatment of these children.”

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