Utility of Synovial Fluid Biomarkers for Culture-Positive Septic Arthritis in a Lyme Disease-Endemic Region

Andzelika Dechnik; Caroline G Kahane; Lise E Nigrovic; Todd W Lyons

doi:10.1097/PEC.0000000000003188

Utility of Synovial Fluid Biomarkers for Culture-Positive Septic Arthritis in a Lyme Disease-Endemic Region

Pediatr Emerg Care. 2024 Apr 2. doi: 10.1097/PEC.0000000000003188. Online ahead of print.

Authors

Andzelika Dechnik¹, Caroline G Kahane², Lise E Nigrovic², Todd W Lyons²

Affiliations

¹ From the Division of Pediatric Emergency Medicine, Department of Emergency Medicine, Columbia University, New York, NY.
² Division of Emergency Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA.

PMID: 38563800
DOI: 10.1097/PEC.0000000000003188

Abstract

Objective: To evaluate the performance of synovial fluid biomarkers to identify children with culture-positive septic arthritis.

Methods: We identified children 6 months to 18 years old presenting to a single emergency department between 2007 and 2022 undergoing evaluation for septic arthritis defined by having a synovial fluid culture obtained. Our primary outcome was septic arthritis defined by a positive synovial fluid culture. We evaluated the ability of synovial fluid biomarkers to identify children with septic arthritis using area under the receiver operating characteristic curve (AUC) analyses. We measured the sensitivity and specificity of commonly used synovial fluid biomarkers.

Results: We included 796 children, of whom 79 (10%) had septic arthritis. Compared with synovial white blood cell count (AUC, 0.72; 95% confidence interval [CI], 0.65-0.78), absolute neutrophil count (AUC, 0.72; 95% CI, 0.66-0.79; P = 0.09), percent neutrophils (AUC, 0.66; 95% CI, 0.60-0.71; P = 0.12), and glucose (AUC, 0.78; 95% CI, 0.67-0.90; P = 0.33) performed similarly, whereas protein (AUC, 0.52; 95% CI, 0.40-0.63, P = 0.04) had lower diagnostic accuracy. Synovial fluid white blood cell count ≥50,000 cells/μL had a sensitivity of 62.0% (95% CI, 50.4%-72.7%) and a specificity of 67.0% (95% CI, 63.4%-70.4%), whereas a positive synovial fluid Gram stain had a sensitivity of 48.1% (95% CI, 36.5%-59.7%) and specificity of 99.1% (95% CI, 98.1%-99.7%) for septic arthritis.

Conclusions: None of the routinely available synovial fluid biomarkers had sufficient accuracy to be used in isolation in the identification of children with septic arthritis. New approaches including multivariate clinical prediction rules and novel biomarkers are needed.