Background/Purpose: Crude prevalence estimates indicate Down’s Arthropathy (DA) is 3-8 times more common than juvenile idiopathic arthritis (JIA), however, DA is still largely under recognized at onset and has a 2 year average delay from onset of symptoms to diagnosis. The majority of DA presents with greater than 5 affected joints, more commonly affecting small joints, and treatment has historically been complex as many don’t tolerate methotrexate (MTX) due toxicity. The objective of this study is to investigate the clinical features and treatment outcomes of DA at our institution.

Methods: In a retrospective chart review, potential DA patients were identified through electronic medical record system (EMR) from January 1, 1995 to December 31, 2015. ICD-9-CM codes were used to identify patients (less than 18 years of age) with both Down syndrome (758.0) and JIA (714.3, 714.31, 714.32, 714.33). Individual charts were then manually reviewed to confirm diagnosis of Down syndrome (DS) and JIA. Chart review included analysis of all documents included in EMR, including clinical visits, imaging studies and laboratory results.

Results: Of 26 identified patients, (3 did not have DS and 2 had incomplete records) 21 met inclusion criteria and were analyzed with a mean follow-up period of 4 years (SD 4.2). Patients were 62% female, and 62% had a polyarticular, RF negative presentation at diagnosis. Within this cohort, there was a mean 19 months (SD 16) delay in diagnosis after symptom onset. At JIA diagnosis 71% reported morning stiffness, and on exam there was an average of 14 active joints (SD 10), and 57% of patients had small joint involvement. Mean physician global assessment of disease activity at diagnosis was 4.9 (SD 2.0). Of 18 patients with imaging at diagnosis, erosive changes were noted in 22%. All patients were started on NSAIDs at diagnosis with 33% simultaneously starting a disease-modifying antirheumatic drug (DMARD), and 5 % a biologic. Over the course of disease 62% used a DMARD (mostly MTX [58%]) and 48% used a biologic (mostly etanercept [90%]). Of those on DMARD therapy 54% were discontinued due to side effects and 56% had inadequate response to first-line biologic therapy. At last visit there was an average of 3 active joints (SD 4) and average MD global of 1.7 (SD 1.6).

Conclusion: Down’s Arthropathy remains under recognized despite having a higher prevalence than JIA. There also remains a significant delay to diagnosis which likely contributes to poorer outcomes. Other barriers that inhibit optimal treatment and outcomes are DMARD toxicity and anti-TNF effectiveness, which appears different compared to those in JIA without DS. Earlier diagnosis through improved screening and more targeted treatment may allow for earlier disease control and better outcomes.