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Utility of Synovial Fluid Biomarkers for Culture-Positive Septic Arthritis in a Lyme Disease-Endemic Region
Andzelika Dechnik1, Caroline G Kahane2, Lise E Nigrovic2
1From the Division of Pediatric Emergency Medicine, Department of Emergency Medicine, Columbia University, New York, NY.
Insights
Synovial fluid biomarkers alone are insufficient for diagnosing septic arthritis in children. New diagnostic approaches are needed to accurately identify this serious joint infection in pediatric patients.
Area of Science:
- Pediatric infectious diseases
- Orthopedic surgery
- Diagnostic marker research
Background:
- Septic arthritis is a serious joint infection in children requiring prompt diagnosis and treatment.
- Accurate identification of septic arthritis is crucial to prevent long-term joint damage.
- Current diagnostic methods rely on synovial fluid analysis, but their performance varies.
Purpose of the Study:
- To assess the diagnostic performance of commonly used synovial fluid biomarkers for identifying culture-positive septic arthritis in children.
- To determine the sensitivity and specificity of various synovial fluid markers.
- To evaluate if any single biomarker is sufficient for diagnosing pediatric septic arthritis.
Main Methods:
- Retrospective analysis of 796 children (6 months to 18 years) evaluated for septic arthritis.
- Synovial fluid cultures were obtained to confirm septic arthritis.
- Area under the receiver operating characteristic curve (AUC) analyses were used to evaluate biomarker performance.
Main Results:
- Of 796 children, 79 (10%) had septic arthritis.
- Synovial fluid glucose (AUC, 0.78) and white blood cell count (AUC, 0.72) showed moderate diagnostic accuracy.
- Protein (AUC, 0.52) had low diagnostic accuracy; a positive Gram stain was highly specific (99.1%) but had low sensitivity (48.1%).
Conclusions:
- No single routinely available synovial fluid biomarker demonstrated sufficient accuracy for isolated use in diagnosing pediatric septic arthritis.
- Current biomarkers have limitations in accurately identifying septic arthritis in children.
- Development of multivariate clinical prediction rules and novel biomarkers is necessary for improved diagnosis.
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.
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