Serum procalcitonin as a diagnostic aid in patients with acute bacterial septic arthritis.

INTRODUCTION

Septic arthritis is a common and serious problem. Early detection and prompt treatment improve outcomes.

OBJECTIVE

To evaluate serum procalcitonin for diagnosis of acute bacterial septic arthritis and to compare its diagnostic utility with synovial white blood cells (WBC), erythrocyte sedimentation rate (ESR) and high-sensitivity C-reactive protein (hs-CRP).

METHOD: A prospective cross-sectional study was performed in 78 Thai patients with acute arthritis. Patients with concomitant infections were excluded. Twenty-eight patients were diagnosed with acute bacterial septic arthritis and 50 patients were diagnosed with acute inflammatory arthritis. Blood samples were collected for complete blood count, ESR, hs-CRP, procalcitonin and hemoculture. Synovial fluid was sent for cell count, Gram stain, crystals identification and culture. The diagnostic accuracy by area under receiver operating characteristic (ROC) curve was calculated.

RESULT: Patients with acute bacterial septic arthritis had higher procalcitonin levels than in acute inflammatory arthritis (mean ± SD = 1.48 ± 2.30 vs. 0.44 ± 0.92 ng/mL, P = 0.032). The cut-off level of procalcitonin was 0.5 ng/mL for which sensitivity, specificity and accuracy for diagnosis of bacterial septic arthritis were 59.3%, 86% and 75.3%, respectively. The ROC curve analysis showed that procalcitonin had a good diagnostic performance (area under the curve = 0.78, 95% CI 0.69-0.89). The area under the curve of hs-CRP and synovial fluid WBC were 0.67 (95% CI 0.55-0.79) and 0.821 (95% CI 0.720-0.923), respectively. Combining procalcitonin with other markers did not provide better sensitivity or specificity than procalcitonin alone.

CONCLUSION

Serum procalcitonin has a potential role in diagnosing acute bacterial septic arthritis, especially if arthrocenthesis cannot be performed.