Biomarker profiling for infection diagnosis in emergency departments: A diagnostic study evaluating C-reactive protein, procalcitonin, Club Cell Protein 16, interleukin-6, chitinase-like protein, and soluble urokinase-type plasminogen activator receptor.

INTRODUCTION

Diagnosing infections in emergency departments (EDs) is vital for prompt and effective treatment. This study evaluates the diagnostic accuracy of six inflammatory biomarkers-CC16, CRP, IL-6, PCT, suPAR, and YKL-40-in ED patients with suspected infections.

MATERIALS AND

METHODS

This was a multicenter diagnostic accuracy study. Adult patients suspected of infections at four Danish EDs were included. We measured biomarker levels at admission and analyzed their diagnostic performance.

RESULTS

The study included 966 patients, with 789 (81.7%) confirmed infections. CRP, IL-6, and PCT demonstrated the highest positive predictive values, recorded at 93% (95% CI, 91-95), 92% (95% CI, 90-94), and 91% (95% CI, 88-93), respectively. However, the negative predictive values of these markers were low, at 35.5 (95% CI, 30.8-40.5), 38.3 (95% CI, 32.5-44.3) and 34.2 (95% CI, 28.9-39.9) respectively at Youden Index. CRP, IL-6, and PCT were the most predictive, with CRP demonstrating an area under the curve (AUC) of 0.79. IL-6 and PCT showed similar levels of accuracy. CC16, suPAR, and YKL-40 displayed AUCs in the range of 0.53-0.64. CRP levels peaked three days after symptoms appeared, whereas PCT levels were highest upon symptom onset at admission. The influence of fever enhanced the sensitivity of IL-6 and PCT.

CONCLUSION

CRP, IL-6, and PCT showed the best diagnostic accuracy among the biomarkers tested but are influenced by the timing of symptom onset and fever presence. CC16, suPAR, and YKL-40 had poor diagnostic accuracy and were considered poor discriminators. Overall, no single biomarker was sufficient to conclusively rule in or rule out infection. These findings support the need for nuanced interpretation when using biomarkers to diagnose infections in ED settings.