Clinical Features and Treatment of Down Syndrome Arthropathy: Experience from Two US Tertiary Hospitals.

BACKGROUND: Arthropathy of Down syndrome (DA) is largely under-recognized, with an average 2-year delay in diagnosis. Most patients present with polyarthritis, and treatment has historically been challenging.

OBJECTIVES: Our objective was to investigate the clinical features and treatment of DA in the largest cohort reported to date.

METHODS: In a retrospective chart review at two tertiary care hospitals, International Classification of Diseases, ninth revision, clinical modification (ICD-9-CM) codes for Down syndrome (DS) and juvenile idiopathic arthritis (JIA), between 1 January 1995 and 31 December 2015, were identified and charts reviewed.

RESULTS: In total, 43 patients were identified, with an average (± standard deviation [SD]) follow-up period of 6 ± 4.4 years. The average age of symptom onset was 7.4 ± 3.9 years, with a mean delay of 19 ± 17 months from symptom onset to diagnosis. At diagnosis, 77% of patients had morning stiffness and 72% had abnormal laboratory values; there was an average of 15 ± 13 active joints (range 1-56). Treatment approaches varied, and there was a significant decrease in joints with active arthritis (p < 0.001), with 25% and 39% having at least one change in disease-modifying antirheumatic drug (DMARD) and biologic therapy, respectively. DMARD therapy was discontinued in 60% because of side effects, and 39% had inadequate response to first-line biologic therapy.

CONCLUSIONS: DA remains under-recognized, with delays in diagnosis and extensive musculoskeletal symptoms at presentation. While DA can improve with current therapy for JIA (corticosteroids, DMARDs, biologics), barriers include medication toxicity, intolerance, and ineffectiveness. Earlier diagnosis through improved screening and more targeted treatment may allow for earlier disease control and better outcomes.