Performance enhancement of procalcitonin by high-sensitivity C-reactive protein at the optimal cutoff in predicting bacteremia in emergency department adult patients

Abstract

Pathogenic bacteremia portends a high mortality risk in adult patients admitted to an Emergency Department (ED). This study aims to investigate the effect of adding high-sensitivity C-reactive protein (hs-CRP) to procalcitonin (PCT) and lactate in predicting bacteremia, Gram-negative (GNB) and Gram-positive bacteremia (GPB), using the optimal cutoff derived from the receiver operating characteristics analysis. We evaluated the diagnostic measures, including the positive-test likelihood (LR+), the negative-test likelihood (LR−), and the diagnostic odds ratio (DOR) using a single-center retrospective analysis design. This Standards for Reporting Diagnostic-compliant study comprised 886 consecutive adults who were admitted to the ED in 2010; to this cohort, a 22.2% prevalence of true bacteremia was subsequently confirmed. At the cutoff of 3.9 μg/L, PCT had a DOR of 5.3 (95% confidence interval [CI]: 3.76–7.61) and LR + of 2.8 (95% CI: 2.3–3.4) in predicting overall bacteremia. Elevated PCT and lactate (cutoff at 2 mmol/L), increased the DOR and LR + to 6.3 (95% CI: 4.27–9.29) and 4.0 (95% CI: 3.1–5.2). The DOR and LR + were further improved to 7.1 (95% CI: 4.2–11.95) and 5.6 (95% CI: 3.7–8.6), respectively, when hs-CRP at the cutoff of 1238 nmol/L was added to PCT plus lactate. High-sensitivity CRP at the cutoff of 1,255 nmol/L can enhance the discriminative power raising DOR and LR + values for GPB. The elevation of hs-CRP at the optimal cutoff might improve the diagnostic performance to predict unspecified bacteremia and GPB, but not GNB.

Keywords:

• Procalcitonin
• lactate
• high-sensitivity C-reactive protein
• bacteremia
• emergency department
• diagnostic performance

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by grants to CTL from the China Medical University Hospital [DMR–99–133], Taichung, Taiwan, and JTH from the Ministry of Science and Technology of Taiwan [MOST 106-2221-E-008-098-MY2]. The funders had no role in the study design, data collection, and analysis, decision to publish, or preparation of the manuscript.