Procalcitonin as a potent marker of bacterial infection in febrile Afro-Caribbean patients at the emergency department

Higher diagnostic accuracy and cost-effectiveness using procalcitonin in the treatment of emergency medicine patients with fever (The HiTEMP study): a multicenter randomized study

Background

Fever is a common symptom in the emergency department(ED). Fever can be caused by bacterial infections, which are treated with antibiotics. Often, bacterial infections cannot be ruled out in the ED using standard diagnostics, and empiric antibiotic treatment is started. Procalcitonin(PCT) is a biomarker for bacterial infections, but its role in an undifferentiated ED population remains unclear. We hypothesize that PCT-guided therapy may reduce antibiotics prescription in undifferentiated febrile ED patients. The primary objectives of this study are to determine a) the efficacy, b) the safety of PCT-guided therapy, and c) the accuracy of the biomarker PCT for bacterial infections. The secondary objective is to study the cost-effectiveness of PCT-guided therapy.

Methods/design

This is a multicenter noninferiority randomized controlled trial. All adult ED patients with fever(≥38.2 °C) are randomized between standard care with and without the addition of a PCT level, after written informed consent.

For efficacy, the reduction of patients receiving antibiotics is calculated, using a superiority analysis: differences between the PCT-guided group and control group are assessed using a Fisher’s exact test, and a multivariable logistic regression analysis to account for the effects of demographic and medical variables on the percentage of febrile patients receiving antibiotics.

Safety consists of a composite endpoint, defined as mortality, intensive care admission and ED return visit within 14 days. Noninferiority of PCT will be tested using a one-sided 95 % confidence interval for the difference in the composite safety endpoint between the PCT-guided and control groups using a noninferiority margin of 7.5 %.

Accuracy of PCT and CRP for the diagnosis of bacterial infections will be reported, using the sensitivity, specificity, and the area under the receiver-operating-characteristic curve in the definitive diagnosis of bacterial infections.

The sample size is 550 patients, which was calculated using a power analysis for all primary objectives. Enrollment of patients started in August 2014 and will last 2 years.

Discussion

PCT may offer a more tailor-made treatment to the individual ED patient with fever. Prospective costs analyses will reveal the economic consequences of implementing PCT-guided therapy in the ED.

This trial is registered in the Dutch trial register

NTR4949

Evaluation of procalcitonin, C-reactive protein, interleukin-6 & serum amyloid A as diagnostic biomarkers of bacterial infection in febrile patients

BACKGROUND & OBJECTIVES

Early identification of bacterial infection in patients with fever is important for prompt treatment. However, the available parameters such as C-reactive protein (CRP) and leukocyte counts are not very specific. This study was aimed to assess the diagnostic value of procalcitonin (PCT), CRP, interleukin-6 (IL-6) and serum amyloid A (SAA) for bacterial infection in febrile patients.

METHODS

Serum samples were collected from febrile patients between January and December 2012 and processed for blood cultures. PCT, IL-6, CRP and SAA levels were measured. The patients were divided into three groups according to the final diagnosis: bacteraemia group (group1), bacterial infection with negative blood culture (group 2) and non-bacterial infection group (group 3).

RESULTS

There were significant (P<0.05) difference in the levels of PCT, CRP, IL-6 and SAA among the three groups. The PCT levels of patients with g0 ram-positive bacterial infections were lower than g0 ram-negative bacterial infections (0.53 vs 2.13, P < 0.01). The best cut-off value to detect bacterial infections was 0.26 ng/ml for PCT. PCT, CRP, IL-6 and SAA had areas under the curve of 0.804, 0.693, 0.658 and 0.687, respectively.

INTERPRETATION & CONCLUSIONS

Our results showed PCT as a valuable marker of bacterial infections in febrile patients. PCT was superior to CRP, IL-6 or SAA in the early identification of bacterial infection. More prospective and large scale studies are warranted to confirm these findings.

Performance of C-reactive protein and procalcitonin to distinguish viral from bacterial and malarial causes of fever in Southeast Asia

BACKGROUND

Poor targeting of antimicrobial drugs contributes to the millions of deaths each year from malaria, pneumonia, and other tropical infectious diseases. While malaria rapid diagnostic tests have improved use of antimalarial drugs, there are no similar tests to guide the use of antibiotics in undifferentiated fevers. In this study we estimate the diagnostic accuracy of two well established biomarkers of bacterial infection, procalcitonin and C-reactive protein (CRP) in discriminating between common viral and bacterial infections in malaria endemic settings of Southeast Asia.

METHODS

Serum procalcitonin and CRP levels were measured in stored serum samples from febrile patients enrolled in three prospective studies conducted in Cambodia, Laos and, Thailand. Of the 1372 patients with a microbiologically confirmed diagnosis, 1105 had a single viral, bacterial or malarial infection. Procalcitonin and CRP levels were compared amongst these aetiological groups and their sensitivity and specificity in distinguishing bacterial infections and bacteraemias from viral infections were estimated using standard thresholds.

RESULTS

Serum concentrations of both biomarkers were significantly higher in bacterial infections and malaria than in viral infections. The AUROC for CRP in discriminating between bacterial and viral infections was 0.83 (0.81-0.86) compared with 0.74 (0.71-0.77) for procalcitonin (p < 0.0001). This relative advantage was evident in all sites and when stratifying patients by age and admission status. For CRP at a threshold of 10 mg/L, the sensitivity of detecting bacterial infections was 95% with a specificity of 49%. At a threshold of 20 mg/L sensitivity was 86% with a specificity of 67%. For procalcitonin at a low threshold of 0.1 ng/mL the sensitivity was 90% with a specificity of 39%. At a higher threshold of 0.5 ng/ul sensitivity was 60% with a specificity of 76%.

CONCLUSION

In samples from febrile patients with mono-infections from rural settings in Southeast Asia, CRP was a highly sensitive and moderately specific biomarker for discriminating between viral and bacterial infections. Use of a CRP rapid test in peripheral health settings could potentially be a simple and affordable measure to better identify patients in need of antibacterial treatment and part of a global strategy to combat the emergence of antibiotic resistance.

Procalcitonin as a biomarker of bacterial infection in sickle cell vaso-occlusive crisis

Sickle cell anaemia (SCA) patients with vaso-occlusive crisis (VOC) have signs of inflammation and it is often difficult to diagnose a bacterial infection in them. This study was undertaken to evaluate the role of serum procalcitonin (PCT) as a biomarker of bacterial infection in acute sickle cell vaso-occlusive crisis. Hundred homozygous SCA patients were studied at Sickle Cell Clinic and Molecular Biology Laboratory, V.S.S. Medical College, Burla, Odisha, India. All the patients were divided into three categories namely category-A (VOC/ACS with SIRS but without evidence of bacterial infection - 66 patients), category-B (VOC/ACS with SIRS and either proven or suspected bacterial infection - 24 patients) and category-C (SCA patients in steady state without VOC/ACS or SIRS - 10 patients). Complete blood count, C-reactive protein (CRP) estimation and PCT measurement were done in all the patients. There was no significant difference in TLC and CRP values between category-A and B. In category-A, the PCT level was <0.5 ng/mL in 83.3% and 0.5–2 ng/mL in 16.7% of cases. In category-B, all the patients had PCT value >0.5 ng/mL with 87.5% of patients having >2 ng/mL. In category-C, PCT value was <0.5 ng/mL. PCT had a high sensitivity (100%) and negative predictive value (100%) for bacterial infection at a cutoff value of 0.5 ng/mL; whereas the specificity is excellent at a cut-off value of 2 ng/mL. SCA patients with VOC/ACS and SIRS having a PCT level of <0.5 ng/mL have a low probability of bacterial infection whereas PCT value of >2 ng/mL is indicative of bacterial infection necessitating early antimicrobial therapy.

Diagnostic usefulness of procalcitonin as a marker of bacteremia in patients with acute pyelonephritis

BACKGROUND

Acute pyelonephritis (APN) is one of the most common community-acquired infections and frequently accompanies bacteremia. The purpose of this study was to investigate the diagnostic role of procalcitonin in predicting bacteremia in patients with APN.

METHODS

We conducted a retrospective study of patients with APN who visited the emergency department (ED) at Samsung Medical Center, Seoul. Predictors of bacteremia were analyzed and receiver operating characteristics (ROC) curves were plotted for procalcitonin, C-reactive protein (CRP), and leukocytes.

RESULTS

During the study period, a total of 147 patients who had microbiologically proven APN and available initial procalcitonin concentrations were identified. Of these, bacteremia was present in 84 patients. Multivariate analysis showed that age, hypotension, and higher procalcitonin concentrations independently predicted the presence of bacteremia. Procalcitonin had better discriminative power than CRP, as reflected by area under the ROC curve analysis (0.746 [95% CI, 0.667-0.826] vs. 0.602 [95% CI, 0.509-0.694], p = 0.02). At a cut-off value of 1.63 μg/L, procalcitonin predicted bacteremia with a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 61.9, 81.0, 81.3, 61.4 and 70.1%, respectively.

CONCLUSION

Procalcitonin concentration could be used as a reliable marker to predict bacteremia in patients with APN in the ED.

Can serum procalcitonin and C-reactive protein as nosocomial infection markers in hospitalized patients without localizing signs?

BACKGROUND

Early diagnosis of infection with the use of valuable markers leads to decreased mortality and morbidity. The aim of this study was to evaluate the value of procalcitonin (PCT) and C-reactive protein (CRP) for detecting nosocomial infection in hospitalized patients without localizing signs.

METHODS

We conducted a prospective observational study on 150 hospitalized patients with fever > 38°C emerging 48-72 hours after their admission at Alzahra Hospital, Isfahan, Iran. The subjects did not have any localizing sign of infection. PCT and CRP values were determined using rapid tests and were compared with results of blood culture as the standard test. The sensitivity, specificity, positive and negative predictive values (PV) and likelihood ratios (LRs) were calculated for both PCT and CRP. Receiver operating characteristic (ROC) curves were also used to evaluate the diagnostic value of the PCT and CRP for detecting nosocomial infections. Finally, the areas under the resulting curves were compared.

RESULTS

PCT had a sensitivity of 57.1%, a specificity of 89.1%, a positive PV of 46.2%, and a negative PV of 92.7% while the corresponding percentages for CRP test were 76.2%, 48%, 19.3%, and 92.5%. PCT marker also had a higher positive LR and lower negative LR than did CRP marker. The observed areas under the ROC curves were 0.73 for CRP (95% CI, 0.63-0.82; p = 0.023) and 0.80 for PCT (95% CI, 0.68-0.91; p = 0.001). The optimal cut-off values (best diagnostic accuracy) were 39 mg/L for CRP and 7.5 ng/mL for PCT.

CONCLUSIONS

Determination of PCT and CRP is a valuable tool for identifying nosocomial infections. PCT showed better specificity, negative and positive PV. However CRP showed significantly better sensitivity compared with PCT. Therefore, these tests should be considered as part of initial work-up for patients with unknown source of infection.