Development of a Scoring System for Differential Diagnosis Between Gout and Septic Arthritis at NongKhai Hospital

Abstract

Patients presenting with acute arthritis must always be differentially diagnosed between gout and septic arthritis, as these conditions share overlapping clinical manifestations but necessitate significantly different management strategies. Although synovial fluid analysis is the diagnostic gold standard, its availability is limited in many healthcare settings due to technical and resource constraints. This study aimed to identify clinical and laboratory factors with statistically significant differences between gout and septic arthritis to develop a screening score for differential diagnosis. A retrospective descriptive study was conducted using the medical records of patients with acute arthritis treated at NongKhai Hospital between 2016 and 2024. Clinical and laboratory variables were compared using the Chi-square test and Multivariable binary logistic regression, with regression coefficients subsequently used to develop the scoring system. Eight significant variables were identified: diabetes mellitus, hypertension and/ or cardiovascular disease (at least one condition), previous arthritis, onset within 1 day, fever, first metatarsophalangeal joint involvement, ankle involvement, and serum uric acid levels greater than 5.88 mg/dL. The 15-point scoring system was categorized into High (≥9 points), Intermediate (5-8 points), and Low (≤4 points) probability groups, with gout probabilities of 97.5%, 55.8%, and 5.6%, respectively. The scoring system showed excellent diagnostic performance, with an AUC of 0.926 (p<0.001, 95%CI 0.884-0.969). This scoring system provides a simple and practical tool, particularly useful in healthcare facilities with limited access to synovial fluid analysis, facilitating accurate diagnosis and timely intervention.