Diagnostic value of serum procalcitonin, lactate, and high-sensitivity C-reactive protein for predicting bacteremia in adult patients in the emergency department

• Published in: PeerJ (San Francisco, CA) CA), 2017-11, Vol.5, p.e4094-e4094, Article e4094
• Main Authors: Lin, Chiung-Tsung, Lu, Jang-Jih, Chen, Yu-Ching, Kok, Victor C, Horng, Jorng-Tzong
• Format: Article
• Language: English
• Subjects: Analysis; Antibiotics; Bacteremia; Bacteria; Bacterial infections; Bacterial sepsis; Blood; Blood culture; C-reactive protein; Diagnosis; Diagnostic odds ratio; Emergency and Critical Care; Emergency medical care; Emergency service; Ethics; Gram-positive bacteria; Hospitals; Hypersensitivity C-reactive protein; Identity theft; Infections; Infectious Diseases; Intensive care; Internal Medicine; Laboratories; Lactate; Lactic acid; Medical examination; Medicine; Mortality; Pathology; Patients; Personal information; Procalcitonin; Proteins; Sensitivity analysis; Sepsis; Septic workup; Statistical analysis
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.4094

Few studies compared the diagnostic value of procalcitonin with a combination of other tests including lactate and high-sensitivity C-reactive protein in the prediction of pathogenic bacteremia in emergency department adult patients. We performed a retrospective study assessing the differences in performances of procalcitonin at a cutoff of 0.5 ng/mL, lactate at a cutoff of 19.8 mg/dL, high-sensitivity C-reactive protein at a cutoff of 0.8 mg/dL and their combinations for predicting bacteremia in emergency department adult patients. Sensitivity, specificity, overall accuracy, positive-test and negative-test likelihood, and diagnostic odds ratio with 95% confidence interval for each test combination were calculated for comparison. The receiver operating characteristic curve for every single test were compared using DeLong's method. We also performed a sensitivity analysis in two expanded patient cohorts to assess the discriminative ability of procalcitonin or test combination. A total of 886 patients formed the initial patient cohort. The area under the receiver operating characteristic curve for discriminating positive blood culture was: procalcitonin = 0.72 (95% CI [0.69-0.75]) with a derived optimal cutoff at 3.9 ng/mL; lactate 0.69 (0.66-0.72) with an optimal cutoff at 17.9 mg/dL; high-sensitivity C-reactive protein 0.56 (0.53-0.59) with an optimal cutoff of 13 mg/dL; with pairwise comparisons showing statistically significant better performance of either procalcitonin or lactate outperforming high-sensitivity C-reactive protein. To predict positive blood cultures, the diagnostic odds ratio for procalcitonin was 3.64 (95% CI [2.46-5.51]), lactate 2.93 (2.09-4.14), and high-sensitivity C-reactive protein 0.91 (0.55-1.55;  = 0.79). About combined tests, the diagnostic odds ratio for procalcitonin and lactate increases were 3.98 (95% CI [2.81-5.63]) for positive blood culture prediction. Elevated procalcitonin level rendered a six-fold increased risk of positive gram-negative bacteremia with a diagnostic odds ratio of 6.44 (95% CI [3.65-12.15]), which showed no further improvement in any test combinations. In the sensitivity analysis, as a single test to predict unspecified, gram-negative and gram-positive bacteremia, procalcitonin performed even better in an expanded cohort of 2,234 adult patients in terms of the diagnostic odds ratio. For adult emergency patients, procalcitonin has an acceptable discriminative ability for bacterial blood culture and a be