The Importance of Differentiating Oligoarticular Juvenile Idiopathic Arthritis From Lyme Arthritis in Pediatric Patients.

Objective This study aims to compare clinical and laboratory features between Lyme arthritis (LA) and oligoarticular juvenile idiopathic arthritis (oligoarticular JIA) by examining several potential predictors in pediatric patients. This study also aims to improve and increase awareness of ways to detect LA and oligoarticular JIA in pediatric patients who present with clinical features of joint pain. Methods A medical chart review was conducted among pediatric patients diagnosed with LA or oligoarticular JIA at John R. Oishei Children's Hospital of Buffalo between January 2014 and September 2018. Patients' diagnoses were identified using the International Classification of Disease 10th Revision code for LA (ICD 10 code A69.23) and oligoarticular JIA (ICD 10 code M08.40). Patients with LA were only included in this study if they (1) exhibited arthritis, (2) tested positive for Lyme antibodies, (3) indicated a positive western blot (WB) of five or more out of 10 proteins by IgG antibodies or at least two of three proteins by IgM antibodies, and (4) at the age of 16 or below at the time of diagnosis. Patients with oligoarticular JIA were included in this study if they (1) exhibited arthritis affecting one to four joints for at least six weeks in the first six months of diagnosis and (2) are at the age of 16 or below at the time of diagnosis after ruling out LA and reactive arthritis. In this study, clinical presentations, physical exam findings during initial healthcare visits, and demographics including age, sex, and race of patients were obtained. In addition, laboratory results including white blood cells (WBCs), hemoglobin (Hgb), platelet count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) level, Lyme antibodies through enzyme-linked immunosorbent assay (ELISA) and WB, synovial fluid analysis for red blood cells (RBCs), nucleated cells, and polymerase chain reaction (PCR) for DNA were also collected and analyzed. Results In our data, ESR and CRP were significantly higher in LA compared to oligoarticular JIA (P=0.0053 and 0.0005, respectively). The mean WBC in the synovial joint fluid was significantly higher in LA compared to oligoarticular JIA (P=0.002). Conclusion LA shares features with oligoarticular JIA. This overlap prevents the creation of a clinically useful predictive model for LA. Therefore, Lyme testing should be performed on all patients presenting with monoarticular and oligoarticular arthritis. In addition, ESR, CRP, and WBC in the synovial joint fluid were significantly higher in LA compared to oligoarticular JIA in our findings. While this difference is not definitive by any means, it may help distinguish between the two in cases where the diagnosis is not clear-cut, and the values of ESR, CRP, and WBC in the joint aspirate may help guide clinical judgment in cases that lack a definitive diagnosis.