C-reactive protein, an early marker of community-acquired sepsis resolution: a multi-center prospective observational study

Biomarker kinetics in the prediction of VAP diagnosis: results from the BioVAP study

Background

Prediction of diagnosis of ventilator-associated pneumonia (VAP) remains difficult. Our aim was to assess the value of biomarker kinetics in VAP prediction.

Methods

We performed a prospective, multicenter, observational study to evaluate predictive accuracy of biomarker kinetics, namely C-reactive protein (CRP), procalcitonin (PCT), mid-region fragment of pro-adrenomedullin (MR-proADM), for VAP management in 211 patients receiving mechanical ventilation for >72 h. For the present analysis, we assessed all (N = 138) mechanically ventilated patients without an infection at admission. The kinetics of each variable, from day 1 to day 6 of mechanical ventilation, was assessed with each variable’s slopes (rate of biomarker change per day), highest level and maximum amplitude of variation (Δ^max).

Results

A total of 35 patients (25.4 %) developed a VAP and were compared with 70 non-infected controls (50.7 %). We excluded 33 patients (23.9 %) who developed a non-VAP nosocomial infection. Among the studied biomarkers, CRP and CRP ratio showed the best performance in VAP prediction. The slope of CRP change over time (adjusted odds ratio [aOR] 1.624, confidence interval [CI]_95% [1.206, 2.189], p = 0.001), the highest CRP ratio concentration (aOR 1.202, CI_95% [1.061, 1.363], p = 0.004) and Δ^max CRP (aOR 1.139, CI_95% [1.039, 1.248], p = 0.006), during the first 6 days of mechanical ventilation, were all significantly associated with VAP development. Both PCT and MR-proADM showed a poor predictive performance as well as temperature and white cell count.

Conclusions

Our results suggest that in patients under mechanical ventilation, daily CRP monitoring was useful in VAP prediction.

Trial registration NCT02078999

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-016-0134-8) contains supplementary material, which is available to authorized users.

Search of Unknown Fever Focus Using PET in Critically Ill Children With Complicated Underlying Diseases

OBJECTIVES

PET/CT with F-fluorodeoxyglucose can be used to image cellular metabolism and has been used for evaluating fever of unknown origin in adults. However, there are limited studies about the role of F-fluorodeoxyglucose PET/CT in evaluation of fever of unknown origin in critically ill children, especially those presenting with complicated underlying diseases under treatment. Here, we report our preliminary experience using F-fluorodeoxyglucose PET/CT in this specific group of patients.

DESIGN

Retrospective observational study.

SETTING

PICUs of a university hospital.

PATIENTS

Nineteen critically ill children (mean age, 5.7 yr old) with complicated underlying diseases requiring intensive care support underwent F-fluorodeoxyglucose PET/CT to evaluate fever of unknown origin. The median hospitalized stay was 34 days (range, 15-235 d) and fever of at least 7 days (mean, 21.6 d; range, 7-52 d). The PET scan was advocated after all routine microbiology, and conventional imaging showed negative or inconclusive results.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The F-fluorodeoxyglucose PET/CT findings (blinded to the final clinical diagnosis) were compared with final histopathology, culture, serology results, or follow-up imaging. A final diagnosis was made in 16 patients (84.2%). F-fluorodeoxyglucose PET/CT accurately localized the source of fever in 14 patients, confers to a sensitivity of 87.5% (14 of 16; 95% CI, 0.604-0.978). A false-positive scan in a patient led to subsequent unnecessary investigations. Two false-negative F-fluorodeoxyglucose PET/CT images were later attributed to relapse of underlying disease in the bone marrow and renal abscesses, respectively. In the other two patients where F-fluorodeoxyglucose PET/CT also showed negative findings, fever subsided shortly thereafter without treatment.

CONCLUSIONS

Our preliminary experience suggests that F-fluorodeoxyglucose PET/CT may be clinically beneficial in evaluating fever of unknown origin in children with complicated underlying diseases mandating intensive support in ICUs if usual investigative methods are unsuccessful. Further large prospective studies are needed to validate these findings.

Role of C-reactive Protein and Tumor Necrosis Factor-Alpha in Differentiating between Ventilator-Associated Pneumonia and Systemic Inflammatory Response Syndrome without Infectious Etiology

BACKGROUND

Differential diagnosis of systemic inflammatory response syndrome (SIRS) with or without infectious cause is critically important in terms of initiating antimicrobial agents in case of infectious etiology such as ventilator-associated pneumonia (VAP). The aim of this study was to determine the diagnostic and prognostic roles of C-reactive protein (CRP) and tumor necrosis factor-alpha (TNF-α) in differentiating between ventilator-associated pneumonia and SIRS without infectious etiology.

MATERIALS AND METHODS

In this prospective observational study, 91 adult intensive care unit (ICU) patients were enrolled. According to established diagnostic criteria, they were classified into three groups of "non-SIRS non-VAP", "SIRS non-VAP" and "SIRS-VAP". Serum CRP and TNF-α were measured on days 1, 3 and 7 of the study and compared using repeated measures ANOVA.

RESULTS

With respect to diagnosis, there was no significant difference in the values of these biomarkers between groups (P>0.05). There was no statistically significant "time trend" for C-reactive protein and TNF-α (P>0.05). Considering both group effect and Time effect, the changes were not significantly different for CRP (P= 0.86) and TNF-α (P=0.69). In contrast, the clinical score and the clinical pulmonary infection score (CPIS) ≥ 6, had 100% specificity for diagnosing VAP. With respect to prognosis, only an unchanged or decreasing TNF-α from day 1 to day 3 was marginally associated with 28-day survival. However, day 1 and day 3 acute physiology and chronic health evaluation II (APACHE II) scores were highly associated with 28-day survival.

CONCLUSION

Unlike clinical scoring system including CPIS and APACHE II, TNF-α and CRP levels were not useful as diagnostic or prognostic biomarkers for differentiating between SIRS with VAP etiology and SIRS without infectious etiology.

Prognostic Value and Daily Trend of Interleukin-6, Neutrophil CD64 Expression, C-Reactive Protein and Lipopolysaccharide-Binding Protein in Critically Ill Patients: Reliable Predictors of Outcome or Not?

Background

Severe sepsis and/or trauma complicated by multiple organ dysfunction syndrome are the leading causes of death in critically ill patients. The aim of this prospective single-centre study was to assess the prognostic value and daily trend of interleukin-6 (IL-6), neutrophil CD64 expression, C-reactive protein (CRP) and lipopolysaccharide-binding protein (LBP) regarding outcome in critically ill patients with severe trauma and/or severe sepsis. Outcome measure was hospital mortality.

Methods

One hundred and two critically ill patients admitted to the intensive care unit of a tertiary university hospital were enrolled in this prospective study. Blood samples were collected on admission (day 1), days 2 and 3.

Results

CD64 index was 1.6-fold higher on day 1 and 1.78-fold higher on day 2 in non-survivors (p<0.05). The area under the curve (AUC) for the CD64 index on day 1 for outcome was 0.727. At a cut-off level of 2.80 sensitivity was 75% and specificity was 65%. Patients with CD64 index level on day 1 higher than 2.80 had 2.4-fold higher probability of dying. Odds ratio is 2.40; 95% CI 0.60–9.67.

Conclusions

CD64 index on day 1 is a fairly good predictor of outcome. AUCs for IL-6, CRP and LBP were < 0.55, suggesting these biomarkers failed to predict outcome.

The C-Reactive Protein/Albumin Ratio as an Independent Predictor of Mortality in Patients with Severe Sepsis or Septic Shock Treated with Early Goal-Directed Therapy

Background

Sepsis, including severe sepsis and septic shock, is a major cause of morbidity and mortality. Albumin and C-reactive protein (CRP) are considered as good diagnostic markers for sepsis. Thus, initial CRP and albumin levels were combined to ascertain their value as an independent predictor of 180-day mortality in patients with severe sepsis and septic shock.

Materials and Methods

We conducted a retrospective cohort study involving 670 patients (>18 years old) who were admitted to the emergency department and who had received a standardized resuscitation algorithm (early goal-directed therapy) for severe sepsis and septic shock, from November 2007 to February 2013, at a tertiary hospital in Seoul, Korea. The outcome measured was 180-day all-cause mortality. A multivariate Cox proportional hazard model was used to identify the independent risk factors for mortality. A receiver operating characteristic (ROC) curve analysis was conducted to compare the predictive accuracy of the CRP/albumin ratio at admission.

Results

The 180-day mortality was 28.35% (190/670). Based on the multivariate Cox proportional hazard analysis, age, the CRP/albumin ratio at admission (adjusted HR 1.06, 95% CI 1.03–1.10, p<0.001), lactate level at admission (adjusted HR 1.10, 95% CI 1.05–1.14, p<0.001), and the Sequential Organ Failure Assessment (SOFA) score at admission (adjusted HR 1.12, 95% CI 1.07–1.18, p<0.001) were independent predictors of 180-day mortality. The area under the curve of CRP alone and the CRP/albumin ratio at admission for 180-day mortality were 0.5620 (P<0.001) and 0.6211 (P<0.001), respectively.

Conclusion

The CRP/albumin ratio was an independent predictor of mortality in patients with severe sepsis or septic shock.

Clinical diagnosis of sepsis and the combined use of biomarkers and culture- and non-culture-based assays

Sepsis is among the most common causes of death in hospitalized patients, and early recognition followed by immediate initiation of therapy is an important concept to improve survival in these patients. According to the definition of sepsis, diagnosis of sepsis requires the recognition of the systemic inflammatory response syndrome (SIRS) caused by infection as well as recognition of possible infection-related organ dysfunctions for diagnosis of severe sepsis or septic shock. Both SIRS and organ dysfunctions may occur frequently in hospitalized patients for various reasons. However, the fast recognition of acute infection as a cause of SIRS and newly developed organ dysfunction may be a demanding task since culture-based results of microbiological samples will be available only days after onset of symptoms. Biomarkers and PCR-based pathogen detection may help the physician in differentiating SIRS from sepsis. Procalcitonin (PCT) is the best investigated biomarker for this purpose. Furthermore, the current data support the usage of PCT for guidance of antimicrobial therapy. C-reactive protein (CRP) may be used to monitor the course of infection but has only limited discriminative capabilities. Interleukin-6 is widely used for its fast response to the infectious stimulus, but conclusive data for the application of this biomarker are missing. None of the available biomarkers can by itself reliably differentiate SIRS from sepsis but can aid and shorten the decision process. PCR-based pathogen detection can theoretically shorten the recognition of the underlying pathogen to about 8 h. However, this technique is expensive and requires additional staff in the laboratory; controlled prospective studies are missing. Although current studies suggest that PCR-based pathogen detection may be useful to shorten time to adequate antimicrobial therapy and diagnose invasive Candida infections, no general recommendations about the application of PCR for the diagnosis of sepsis can be given.

Targeting C-Reactive Protein in Inflammatory Disease by Preventing Conformational Changes

C-reactive protein (CRP) is a pentraxin that has long been employed as a marker of inflammation in clinical practice. Recent findings brought up the idea of CRP to be not only a systemic marker but also a mediator of inflammation. New studies focused on structural changes of the plasma protein, revealing the existence of two distinct protein conformations associated with opposed inflammatory properties. Native, pentameric CRP (pCRP) is considered to be the circulating precursor form of monomeric CRP (mCRP) that has been identified to be strongly proinflammatory. Recently, a dissociation mechanism of pCRP has been identified on activated platelets and activated/apoptotic cells associated with the amplification of the proinflammatory potential. Correspondingly, CRP deposits found in inflamed tissues have been identified to exhibit the monomeric conformation by using conformation-specific antibodies. Here we review the current literature on the causal role of the dissociation mechanism of pCRP and the genesis of mCRP for the amplification of the proinflammatory potential in inflammatory reactions such as atherosclerosis and ischemia/reperfusion injury. The chance to prevent the formation of proinflammatory mediators in ubiquitous inflammatory cascades has pushed therapeutic strategies by targeting pCRP dissociation in inflammation. In this respect, the development of clinically applicable derivatives of the palindromic compound 1,6-bis(phosphocholine)-hexane (1,6-bis PC) should be a major focus of future CRP research.

Diagnosis and treatment of bacteremia and endocarditis due to Staphylococcus aureus. A clinical guideline from the Spanish Society of Clinical Microbiology and Infectious Diseases (SEIMC)

Both bacteremia and infective endocarditis caused by Staphylococcus aureus are common and severe diseases. The prognosis may darken not infrequently, especially in the presence of intracardiac devices or methicillin-resistance. Indeed, the optimization of the antimicrobial therapy is a key step in the outcome of these infections. The high rates of treatment failure and the increasing interest in the influence of vancomycin susceptibility in the outcome of infections caused by both methicillin-susceptible and -resistant isolates has led to the research of novel therapeutic schemes. Specifically, the interest raised in recent years on the new antimicrobials with activity against methicillin-resistant staphylococci has been also extended to infections caused by susceptible strains, which still carry the most important burden of infection. Recent clinical and experimental research has focused in the activity of new combinations of antimicrobials, their indication and role still being debatable. Also, the impact of an appropriate empirical antimicrobial treatment has acquired relevance in recent years. Finally, it is noteworthy the impact of the implementation of a systematic bundle of measures for improving the outcome. The aim of this clinical guideline is to provide an ensemble of recommendations in order to improve the treatment and prognosis of bacteremia and infective endocarditis caused by S. aureus, in accordance to the latest evidence published.

Serum C-reactive protein concentrations in early abdominal and pulmonary sepsis

Objectives

To evaluate the C-reactive protein serum levels in patients with pulmonary and abdominal sepsis during the first five days of sepsis progression.

Methods

The present investigation was a retrospective cohort study conducted at the university hospital with 345 patients who were admitted to the intensive care unit and diagnosed with sepsis of pulmonary or abdominal origin. Serum C-reactive protein concentrations were measured by the turbidimetric immunoassay. For analysis of C-reactive protein, day 1 was defined as the day on which the patient was clinically diagnosed with sepsis.

Results

Thirty-four patients with sepsis (9.8%), 114 patients with severe sepsis (33.0%), and 197 patients with septic shock (57.2%) were evaluated. The age of the patients was 56.4±19.8 years. The serum C-reactive protein concentrations were higher on the day of sepsis diagnosis in the group with abdominal infection compared with the group with pulmonary sepsis (17.8±10.1 mg/dL versus 14.9±11.1 mg/dL, p=0.025) and remained significantly higher during the first five days of sepsis progression.

Conclusion

The serum C-reactive protein concentrations were significantly higher in the patients with abdominal sepsis compared with the patients with pulmonary sepsis during the first five days of sepsis progression.

Serum Sodium: A Reliable and Validated Predictor for Mortality in Enteric Fistula Patients Complicated with Sepsis

PURPOSE

The aim was to evaluate the predictive value of serial serum sodium determination for mortality in enteric fistula (EF) patients complicated with sepsis.

METHODS

Between January 1(st), 2012 to January 13(th), 2013, we performed a prospective observational study enrolling 162 patients. Patients were divided into survivors group (n = 119) and nonsurvivors group (n = 43) according to 28-day outcomes. Laboratory variables on day 0, day 3, and day 7 after admission were recorded. [Na(+)]0 was defined as serum [Na(+)] value on admission. [Na(+)]3 was defined as serum [Na(+)] value on day 3. Δ [Na(+)]3 was defined as changes from [Na(+)]3 to [Na(+)]0. The definition applied to other parameters. The results were validated in an independent cohort of 116 patients.

RESULTS

ROC analysis showed that [Na(+)]7>147.5 mmol/L and ΔNa7>5.2 mmol/L were reliable predictors ([Na(+)]7: 81.2% sensitivity, 87.7% specificity, (area under the curve(AUC):0.872, p < .001; Δ[Na(+)]7: 81.3% sensitivity, 83.6% specificity, AUC:0.836, p < .001) for mortality. The combination form ([Na(+)]7>147.5 mmol/L+ Δ[Na]7>5.2 mmol/L+ ΔPCT7<5.3 ng/ml) had greatest predictive value (AUC:0.899, p < .001). Their predictive values were confirmed in the validation cohort.

CONCLUSIONS

Serum sodium was a reliable predictor for mortality in abdominal septic patients, which should be paid close attention in the critical care.

Soluble urokinase-type plasminogen activator receptor (suPAR) – a possible biomarker for bacteremia in sepsis / Forma solubilă a receptorului pentru activatorul de plasminogen de tip urokinază (suPAR) – un biomarker posibil pentru bacteriemie în sepsis

Background. Validating new sepsis biomarkers can contribute to early diagnosis and initiation of therapy. The aim of this study is to evaluate the sepsis predictive capacity of soluble urokinase plasminogen receptor (suPAR) and its role in evaluating the prognosis of bloodstream infections. Material and method. We conducted a prospective pilot study on 49 systemic inflammatory response syndrome (SIRS) patients admitted to the intensive care unit (ICU), that were divided, on the basis of bacteremia in group A (SIRS with bacteremia, n=14) and group B (SIRS without bacteremia, n=35). Hemoculture and blood samples were drawn on the first day to determine suPAR, C-reactive protein (CRP) and procalcitonin (PCT). We set to identify significant cut-off values in estimating bacteremia and mortality in septic patients. Results. In group A, suPAR values were 14.3 ng/mL (range 10-45.5 ng/mL) and in group B, 9.85 ng/mL (range 3.4-48 ng/mL) p=0.008. Area under the curve (AUC) for suPAR was 0.745 (95% CI: 0.600-0.859), for CRP 0.613 (95% CI: 0.522-0.799) and for PCT 0.718 (95% CI: 0.477-0.769). Cut-off value for suPAR in bacteremia prediction was 9.885 ng/mL, with 100% sensibility and 51.43% specificity. Mortality in group A was 85.7% (12/14) and in group B 74.3% (26/39), p>0.05. Area under the curve (AUC) for suPAR was 0.750 (95% CI: 0.455-0.936), for CRP 0.613 (95% CI: 0.413-0.913) and for PCT 0.618 (95% CI: 0.373-0.888). Cut-off value of suPAR in predicting mortality was 11.5 ng/mL, with 66.67% sensibility and 100% specificity. Conclusions. In our study suPAR had a predictive capacity for bacteremia and seems to be an independent factor for mortality prognosis in septic patients.

Direct bilirubin as a prognostic biomarker in enteric fistula patients complicated with sepsis: a case-control study

OBJECTIVE

The objective of this study was to evaluate the predictive value of serial bilirubin determinations for mortality in enteric fistula (EF) patients complicated with sepsis.

METHODS

From January 1st, 2012 to January 13rd, 2013, a prospective study enrolling 162 patients was performed. Patients were divided into the survivors group (n = 119) and non-survivors group (n = 43) according to 28-day outcomes. Laboratory variables on day 0, day 3 and day 7 after admission were recorded. DB0 was defined as serum direct bilirubin (DB) value in admission, while ΔDB3 as the changes from DB3 to DB0. The definition applied to other parameters. The results were validated in an independent cohort of 116 patients.

RESULTS

Compared with survivors, non-survivors had significantly higher DB7 (23.1 ± 10.6 vs. 11.2 ± 1.1, P < 0.001) and procalcitonin (PCT7) (5.2 ± 2.8 vs. 1.7 ± 0.3 P = 0.006). ROC analysis showed that DB7 > 12.8 μmol/L and ΔDB7 > 7.3 μmol/L were reliable predictors (DB7: 86.4% sensitivity, 88.6% specificity (area under the curve (AUC): 0.881, P < 0.001; ΔDB7: 84.4% sensitivity, 85.1% specificity, AUC: 0.865, P < 0.001) for mortality.The combination form (DB7 > 12.8 μmol/L + ΔPCT7 < 5.3 ng/ml) had greatest predictive value (AUC: 0.894, P < 0.001). Their predictive values were confirmed in the validation cohort.

CONCLUSIONS

Serum direct bilirubin was a reliable predictor for mortality in enteric fistula patients, which should be paid close attention in the critical care.

The influence of statin exposure on inflammatory markers in patients with early bacterial infection: pilot prospective cohort study

BACKGROUND

In the context of infection, progressive illness resulting in acute organ dysfunction is thought to be secondary to inflammatory response. Our aims were to determine risk factors for progressive illness following infection in a low-risk hospitalised cohort, including the impact of prior stain therapy.

METHODS

We performed a prospective observational cohort study on two adult acute medical wards of a single tertiary academic hospital. We screened drug prescription charts of all adult acute medical admissions for inclusion criteria of inpatient administration of antibiotics for more than 24 hours for a microbiologically confirmed or clinically suspected infection. Patients were followed until admission to a high dependency unit (HDU) or intensive care unit (ICU), discharge from hospital, or to a maximum of 10 days. Outcomes were evolution of systemic inflammatory response syndrome (SIRS) criteria, white cell count and C-reactive protein measurements, and adverse clinical outcomes. We constructed multivariable models accounting for repeated within-patient measurements to determine associations between a priori selected predictors (days since admission, age, gender, Charlson score, prior statin exposure) and selected outcomes.

RESULTS

We enrolled 209 patients; 27.8% were statin users and the commonest infection was pneumonia (51.0%). Most (88.0%) had at least 1 SIRS criterion on admission, and 76 (37.3%) manifested additional SIRS criteria over time. Risks of admission to HDU/ICU (3.3%) and of 30-day mortality (5.7%) were low. The proportion of patients with at least 1 SIRS criterion, mean CRP, and mean WBC all decreased over time. Multivariable regression models identified days since hospital admission as the only variable associated with daily presence of SIRS criteria, WCC, or CRP (adjusted OR <1 and p < 0.0001 in all analyses). Statin exposure was not a significant predictor.

CONCLUSIONS

This cohort of ward patients treated for infection had a low risk of clinical deterioration, inflammatory markers improved over time, and statin exposure was not associated with any outcome. Future larger studies may identify risk factors for progression of illness in this population and plausible surrogate endpoints for evaluation in clinical trials.

Biomarkers in polytrauma induced systemic inflammatory response syndrome and sepsis - a narrative review

Polytrauma still represents one of the leading causes of death in the first four decades of life. Septic complications represent the predominant causes of late death in polytrauma patients. Early diagnosis and treatment of infection is associated with an improved clinical outcome and reduced mortality. Several biomarkers have been evaluated for making early diagnosis of sepsis. Current evidence does not support the use of a single biomarker in diagnosing septic complications. Procalcitonin trend was found to be useful in early identification of post-traumatic sepsis.

Rapid diagnosis of sepsis

Fast and appropriate therapy is the cornerstone in the therapy of sepsis. However, the discrimination of sepsis from non-infectious causes of inflammation may be difficult. Biomarkers have been suggested to aid physicians in this decision. There is currently no biochemical technique available which alone allows a rapid and reliable discrimination between sepsis and non-infectious inflammation. Procalcitonin (PCT) is currently the most investigated biomarker for this purpose. C-reactive protein and interleukin 6 perform inferior to PCT in most studies and their value in diagnosing sepsis is not defined. All biomarkers including PCT are also released after various non-infectious inflammatory impacts. This shortcoming needs to be taken into account when biomarkers are used to aid the physician in the diagnosis of sepsis. Polymerase chain reaction (PCR) based pathogen detection may improve time to adequate therapy but cannot rule out the presence of infection when negative.

Interpretation of C-reactive protein concentrations in critically ill patients

Infection is often difficult to recognize in critically ill patients because of the marked coexisting inflammatory process. Lack of early recognition prevents timely resuscitation and effective antimicrobial therapy, resulting in increased morbidity and mortality. Measurement of a biomarker, such as C-reactive protein (CRP) concentration, in addition to history and physical signs, could facilitate diagnosis. Although frequently measured in clinical practice, few studies have reported on the pathophysiological role of this biomarker and its predictive value in critically ill patients. In this review, we discuss the pathophysiological role of CRP and its potential interpretation in the inflammatory processes observed in critically ill patients.

Sepsis: multiple abnormalities, heterogeneous responses, and evolving understanding

Sepsis represents the host's systemic inflammatory response to a severe infection. It causes substantial human morbidity resulting in hundreds of thousands of deaths each year. Despite decades of intense research, the basic mechanisms still remain elusive. In either experimental animal models of sepsis or human patients, there are substantial physiological changes, many of which may result in subsequent organ injury. Variations in age, gender, and medical comorbidities including diabetes and renal failure create additional complexity that influence the outcomes in septic patients. Specific system-based alterations, such as the coagulopathy observed in sepsis, offer both potential insight and possible therapeutic targets. Intracellular stress induces changes in the endoplasmic reticulum yielding misfolded proteins that contribute to the underlying pathophysiological changes. With these multiple changes it is difficult to precisely classify an individual's response in sepsis as proinflammatory or immunosuppressed. This heterogeneity also may explain why most therapeutic interventions have not improved survival. Given the complexity of sepsis, biomarkers and mathematical models offer potential guidance once they have been carefully validated. This review discusses each of these important factors to provide a framework for understanding the complex and current challenges of managing the septic patient. Clinical trial failures and the therapeutic interventions that have proven successful are also discussed.

Sepsis patients do not differ in health-related quality of life compared with other ICU patients

INTRODUCTION

The aim of the present multicentre study is to assess health-related quality of life in patients with community-acquired sepsis, severe sepsis, or septic shock (CAS) 6 months after discharge from the intensive care unit (ICU) and to compare the health-related quality of life of the ICU survivors with CAS with ICU survivors with other ICU diagnoses.

METHODS

Prospective, multicentre study in nine combined medical and surgical ICUs in Portugal. Health-related quality of life was assessed 6 months after ICU stay, using EuroQol-5D (EQ-5D) mailed to patients. ICU-related factors were obtained from the local ICU database and the local database for the SACiUCI follow-up study.

RESULTS

A total of 313 (52%) surviving patients answered the questionnaire, and of these 91 (29%) were admitted for CAS. There were no significant differences in health-related quality of life between the two study groups.

CONCLUSION

Patients admitted to ICU for CAS did not perceived different health-related quality of life compared with ICU patients admitted for other diagnoses.

Diagnostic and prognostic markers in sepsis

Sepsis is a common and serious complication in intensive care unit patients. An important factor in optimizing survival rates in septic patients is the ability to start treatment early in the course of disease; there is, therefore, a need for accurate diagnostic tests. In recent years, there has been a move away from the rather vague and nonspecific signs that were previously used to diagnose sepsis towards the possible adjunctive role of biomarkers. Many biomarkers have been proposed and assessed clinically, but none alone is specific enough to definitively determine diagnosis. The future direction of research is most likely a greater focus on the use of panels or combinations of markers with clinical signs. Some biomarkers may also be useful for prognosis and guiding therapy. Here, the authors will review our changing approaches to sepsis diagnosis and discuss some of the markers that seem most relevant at the present time.

Hospital mortality prognostication in sepsis using the new biomarkers suPAR and proADM in a single determination on ICU admission

PURPOSE

The soluble form of the urokinase-type plasminogen activator receptor (suPAR) and proadrenomedullin (proADM) are two new and promising sepsis biomarkers. We assessed the prognostic value of a single determination of proADM and suPAR, comparing them with C-reactive protein (CRP) and procalcitonin (PCT), and evaluating whether their addition to severity scores (APACHE II and SOFA) could improve their prognostic accuracy.

METHODS

A single-centre prospective observational study conducted in an adult intensive care department at Marques de Valdecilla University Hospital in Spain. APACHE II and SOFA scores, CRP, PCT, suPAR and proADM levels on the day of ICU admission were collected.

RESULTS

A total of 137 consecutive septic patients were studied. The best area under the curve (AUC) for the prediction of in-hospital mortality was for APACHE II (0.82) and SOFA (0.75) scores. The ROC curve for suPAR yielded an AUC of 0.67, higher than proADM (0.62), CRP (0.50) and PCT (0.44). Significant dose-response trends were found between hospital mortality and suPAR (OR Q4 = 4.83, 95% CI 1.60-14.62) and pro-ADM (OR Q4 = 3.00, 95% CI 1.06-8.46) quartiles. Non-significant associations were found for PCT and CRP. The combination of severity scores and each biomarker did not provide superior AUCs.

CONCLUSIONS

SuPAR and, to a lesser extent, proADM levels on ICU admission were better tools in prognosticating in-hospital mortality than CRP or PCT. However, neither of the two new biomarkers has been demonstrated to be excessively useful in the current setting. The prognostic accuracy was better for severity scores than for any of the biomarkers.

Age-related differences in symptoms, diagnosis and prognosis of bacteremia

Background

Elderly patients are at particular risk for bacteremia and sepsis. Atypical presentation may complicate the diagnosis. We studied patients with bacteremia, in order to assess possible age-related effects on the clinical presentation and course of severe infections.

Methods

We reviewed the records of 680 patients hospitalized between 1994 and 2004. All patients were diagnosed with bacteremia, 450 caused by Escherichia coli and 230 by Streptococcus pneumoniae. Descriptive analyses were performed for three age groups (< 65 years, 65–84 years, ≥ 85 years). In multivariate analyses age was dichotomized (< 65, ≥ 65 years). Symptoms were categorized into atypical or typical. Prognostic sensitivity of CRP and SIRS in identifying early organ failure was studied at different cut-off values. Outcome variables were organ failure within one day after admission and in-hospital mortality.

Results

The higher age-groups more often presented atypical symptoms (p <0.001), decline in general health (p=0.029), and higher in-hospital mortality (p<0.001). The prognostic sensitivity of CRP did not differ between age groups, but in those ≥ 85 years the prognostic sensitivity of two SIRS criteria was lower than that of three criteria. Classical symptoms were protective for early organ failure (OR 0.67, 95% CI 0.45-0.99), and risk factors included; age ≥ 65 years (OR 1.65, 95% CI 1.09-2.49), comorbid illnesses (OR 1.19, 95% CI 1.02-1.40 per diagnosis), decline in general health (OR 2.28, 95% CI 1.58-3.27), tachycardia (OR 1.50, 95% CI 1.02-2.20), tachypnea (OR 3.86, 95% CI 2.64-5.66), and leukopenia (OR 4.16, 95% CI 1.59-10.91). Fever was protective for in-hospital mortality (OR 0.46, 95% CI 0.24-0.89), and risk factors included; age ≥ 65 years (OR 15.02, 95% CI 3.68-61.29), ≥ 1 comorbid illness (OR 2.61, 95% CI 1.11-6.14), bacteremia caused by S. pneumoniae (OR 2.79, 95% CI 1.43-5.46), leukopenia (OR 4.62, 95% CI 1.88-11.37), and number of early failing organs (OR 3.06, 95% CI 2.20-4.27 per failing organ).

Conclusions

Elderly patients with bacteremia more often present with atypical symptoms and reduced general health. The SIRS-criteria have poorer sensitivity for identifying organ failure in these patients. Advanced age, comorbidity, decline in general health, pneumococcal infection, and absence of classical symptoms are markers of a poor prognosis.

High-sensitivity C-reactive protein and risk of sepsis

Background

Conventional C-reactive protein assays have been used to detect or guide the treatment of acute sepsis. The objective of this study was to determine the association between elevated baseline high-sensitivity C-reactive protein (hsCRP) and the risk of future sepsis events.

Methods

We studied data from 30,239 community dwelling, black and white individuals, age ≥45 years old enrolled in the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort. Baseline hsCRP and participant characteristics were determined at the start of the study. We identified sepsis events through review of hospital records. Elevated hsCRP was defined as values >3.0 mg/L. Using Cox regression, we determined the association between elevated hsCRP and first sepsis event, adjusting for sociodemographic factors (age, sex, race, region, education, income), health behaviors (tobacco and alcohol use), chronic medical conditions (coronary artery disease, diabetes, dyslipidemia, hypertension, chronic kidney disease, chronic lung disease) and statin use.

Results

Over the mean observation time of 5.7 years (IQR 4.5–7.1), 974 individuals experienced a sepsis event, and 11,447 (37.9%) had elevated baseline hsCRP (>3.0 mg/L). Elevated baseline hsCRP was independently associated with subsequent sepsis (adjusted HR 1.56; 95% CI 1.36–1.79), adjusted for sociodemographics, health behaviors, chronic medical conditions and statin use.

Conclusion

Elevated baseline hsCRP was associated with increased risk of future sepsis events. hsCRP may help to identify individuals at increased risk for sepsis.

Changes in circulating procalcitonin versus C-reactive protein in predicting evolution of infectious disease in febrile, critically ill patients

Objective

Although absolute values for C-reactive protein (CRP) and procalcitonin (PCT) are well known to predict sepsis in the critically ill, it remains unclear how changes in CRP and PCT compare in predicting evolution of: infectious disease, invasiveness and severity (e.g. development of septic shock, organ failure and non-survival) in response to treatment. The current study attempts to clarify these aspects.

Methods

In 72 critically ill patients with new onset fever, CRP and PCT were measured on Day 0, 1, 2 and 7 after inclusion, and clinical courses were documented over a week with follow up to Day 28. Infection was microbiologically defined, while septic shock was defined as infection plus shock. The sequential organ failure assessment (SOFA) score was assessed.

Results

From peak at Day 0–2 to Day 7, CRP decreased when (bloodstream) infection and septic shock (Day 0–2) resolved and increased when complications such as a new (bloodstream) infection or septic shock (Day 3–7) supervened. PCT decreased when septic shock resolved and increased when a new bloodstream infection or septic shock supervened. Increased or unchanged SOFA scores were best predicted by PCT increases and Day 7 PCT, in turn, was predictive for 28-day outcome.

Conclusion

The data, obtained during ICU-acquired fever and infections, suggest that CRP may be favoured over PCT courses in judging response to antibiotic treatment. PCT, however, may better indicate the risk of complications, such as bloodstream infection, septic shock, organ failure and mortality, and therefore might help deciding on safe discontinuation of antibiotics. The analysis may thus help interpreting current literature and design future studies on guiding antibiotic therapy in the ICU.

C-reactive protein versus erythrocyte sedimentation rate, white blood cell count and alkaline phosphatase in diagnosing bacteraemia in bone and joint infections

AIM

Bacteraemia is common in childhood acute bone and joint infections and demands urgent treatment. Blood C-reactive protein (CRP), erythrocyte sedimentation rate and white blood cell count (WBC) are well known and established markers in these infections. Instead, no information is available on serum alkaline phosphatase whose concentration is known to increase in septic conditions.

METHODS

In our large prospective treatment trial comprising of 265 children with acute culture-positive bone or joint infection, all these laboratory indices were monitored on admission to hospital. The predictive value to detect bacteraemia was assessed for each of these four indices.

RESULTS

In all, 59% of the patients showed bacteraemia. CRP was significantly (P < 0.05) higher among bacteraemic patients, whereas erythrocyte sedimentation rate, white blood cell count and alkaline phosphatase were not. The area under receiver operator characteristic curve for CRP was 0.588 (CI95% 0.524-0.649) and the significance level P (Area = 0.5) was <0.05.

CONCLUSION

None of the markers could reliably diagnose bacteraemia. CRP alone was significantly higher among bacteraemic patients.

New markers in pneumonia

Pneumonia is one of the most common causes of death from infectious diseases worldwide, and the most common fatal infection acquired in hospitals. Despite advances in prevention strategies, such as antibiotic therapies and intensive care, significant improvement in the mortality rate is still lacking. This high mortality is largely due to the limitations in current clinical practices and laboratory tests, which delay the timing of adequate antibiotic therapy. In recent years, many indicators (biomarkers) are present in scenarios where infectious pathogens invade into the body. These biomarkers, as reflected in specific biological responses to infections, have been reported to demonstrate the ability to facilitate the diagnosis, risk stratification, and management of pneumonia. This review provides a schematic overview of these new potential biomarkers based on the categories of (1) microorganisms and their derivatives, (2) inflammation mediators, (3) inflammation response proteins, and (4) stress-sensing proteins. In addition, approaches to identifying new biomarkers are also briefly introduced. Although no current biomarker can solely achieve a definitive diagnosis, many of them can be complemented, rather than replaced outright, in routine clinical practices to improve decision-making processes regarding pneumonia.

New approaches to sepsis: molecular diagnostics and biomarkers

Sepsis is among the most common causes of death in hospitals. It arises from the host response to infection. Currently, diagnosis relies on nonspecific physiological criteria and culture-based pathogen detection. This results in diagnostic uncertainty, therapeutic delays, the mis- and overuse of antibiotics, and the failure to identify patients who might benefit from immunomodulatory therapies. There is a need for new sepsis biomarkers that can aid in therapeutic decision making and add information about screening, diagnosis, risk stratification, and monitoring of the response to therapy. The host response involves hundreds of mediators and single molecules, many of which have been proposed as biomarkers. It is, however, unlikely that one single biomarker is able to satisfy all the needs and expectations for sepsis research and management. Among biomarkers that are measurable by assays approved for clinical use, procalcitonin (PCT) has shown some usefulness as an infection marker and for antibiotic stewardship. Other possible new approaches consist of molecular strategies to improve pathogen detection and molecular diagnostics and prognostics based on transcriptomic, proteomic, or metabolic profiling. Novel approaches to sepsis promise to transform sepsis from a physiologic syndrome into a group of distinct biochemical disorders and help in the development of better diagnostic tools and effective adjunctive sepsis therapies.

The predisposition, infection, response and organ failure (Piro) sepsis classification system: results of hospital mortality using a novel concept and methodological approach

Introduction

PIRO is a conceptual classification system in which a number of demographic, clinical, biological and laboratory variables are used to stratify patients with sepsis in categories with different outcomes, including mortality rates.

Objectives

To identify variables to be included in each component of PIRO aiming to improve the hospital mortality prediction.

Methods

Patients were selected from the Portuguese ICU-admitted community-acquired sepsis study (SACiUCI). Variables concerning the R and O component included repeated measurements along the first five days in ICU stay. The trends of these variables were summarized as the initial value at day 1 (D1) and the slope of the tendency during the five days, using a linear mixed model. Logistic regression models were built to assess the best set of covariates that predicted hospital mortality.

Results

A total of 891 patients (age 60±17 years, 64% men, 38% hospital mortality) were studied. Factors significantly associated with mortality for P component were gender, age, chronic liver failure, chronic renal failure and metastatic cancer; for I component were positive blood cultures, guideline concordant antibiotic therapy and health-care associated sepsis; for R component were C-reactive protein slope, D1 heart rate, heart rate slope, D1 neutrophils and neutrophils slope; for O component were D1 serum lactate, serum lactate slope, D1 SOFA and SOFA slope. The relative weight of each component of PIRO was calculated. The combination of these four results into a single-value predictor of hospital mortality presented an AUC-ROC 0.84 (IC_95%:0.81–0.87) and a test of goodness-of-fit (Hosmer and Lemeshow) of p = 0.368.

Conclusions

We identified specific variables associated with each of the four components of PIRO, including biomarkers and a dynamic view of the patient daily clinical course. This novel approach to PIRO concept and overall score can be a better predictor of mortality for patients with community-acquired sepsis admitted to ICUs.

Pentraxins in nephrology: C-reactive protein, serum amyloid P and pentraxin-3

Every clinician uses C-reactive protein (CRP) levels as a biomarker for systemic inflammation in acute disorders. Nephrologists also consider CRP levels as a predictor for overall mortality in patients with chronic kidney disease or end-stage renal disease. But what is the biological function of CRP? CRP is a member of the family of pentraxins, which are small pentameric innate immunity effector proteins. Pentraxins are absent or weakly expressed during homeostasis. However, the pro-inflammatory cytokines interleukin (IL)-1, IL-6 and tumour necrosis factor induce CRP and serum amyloid P (SAP) in hepatocytes, whereas the long pentraxins, such as pentraxin (PTX)-3, are produced in peripheral tissues and monocytic phagocytes. Pentraxins opsonize pathogens or other particles such as dead cells, for their phagocytic clearance or induce pathogen killing in extracellular compartments. In this review, we discuss the immunoregulatory properties of the different members of the pentraxin family. We discuss the evolving evidence demonstrating their roles in acute and chronic forms of kidney disease and the significance of SAP and PTX3 as additional biomarkers of innate immune activation and systemic inflammation.

Patterns of c-reactive protein RATIO response in severe community-acquired pneumonia: a cohort study

INTRODUCTION

Community-acquired pneumonia (CAP) requiring intensive care unit (ICU) admission remains a severe medical condition, presenting ICU mortality rates reaching 30%. The aim of this study was to assess the value of different patterns of C-reactive protein (CRP)-ratio response to antibiotic therapy in patients with severe CAP requiring ICU admission as an early maker of outcome.

METHODS

In total, 191 patients with severe CAP were prospectively included and CRP was sampled every other day from D1 to D7 of antibiotic prescription. CRP-ratio was calculated in relation to D1 CRP concentration. Patients were classified according to an individual pattern of CRP-ratio response with the following criteria: fast response - when D5 CRP was less than or equal to 0.4 of D1 CRP concentration; slow response - when D5 CRP was > 0.4 and D7 less than or equal to 0.8 of D1 CRP concentration; nonresponse - when D7 CRP was > 0.8 of D1 CRP concentration. Comparison between ICU survivors and non-survivors was performed.

RESULTS

CRP-ratio from D1 to D7 decreased faster in survivors than in non-survivors (p = 0.01). The ability of CRP-ratio by D5 to predict ICU outcome assessed by the area under the ROC curve was 0.73 (95% Confidence Interval, 0.64 - 0.82). By D5, a CRP concentration above 0.5 of the initial level was a marker of poor outcome (sensitivity 0.81, specificity 0.58, positive likelihood ratio 1.93, negative likelihood ratio 0.33). The time-dependent analysis of CRP-ratio of the three patterns (fast response n = 66; slow response n = 81; nonresponse n = 44) was significantly different between groups (p < 0.001). The ICU mortality rate was considerably different according to the patterns of CRP-ratio response: fast response 4.8%, slow response 17.3% and nonresponse 36.4% (p < 0.001).

CONCLUSIONS

In severe CAP, sequential evaluation of CRP-ratio was useful in the early identification of patients with poor outcome. The evaluation of CRP-ratio pattern of response to antibiotics during the first week of therapy was useful in the recognition of the individual clinical evolution.

Predictors of survival in sepsis: what is the best inflammatory marker to measure?

PURPOSE OF REVIEW

Sepsis is relevant due to its high morbidity and mortality. For both sepsis diagnosis and outcome prediction many biomarkers have been described in the literature. Most of these markers are objects of scientific interest rather than being introduced into daily clinical practice. However, due to their unspecific character and their insufficient predictive value for the individual person, research focus is still on new aspects in sepsis-related biomarkers.

RECENT FINDINGS

Beyond the widely used acute-phase proteins C-reactive protein (CRP) and procalcitonin (PCT), many new molecules have been studied deriving from different organs or cells affected, due to the systemic nature of sepsis. Cytokines, coagulation factors/characteristics, vasoactive hormones, and several others have been recently proved to be relevant in sepsis syndrome and probably useful for outcome prediction. However, single time point measurements may be less predictive than consideration of the time-dependent course of parameters. Clinical decision just based on a biomarker is still not feasible because of the huge inter-individual differences in the inflammatory response.

SUMMARY

Many biomarkers display relevant correlation with the clinical outcome of patients with severe sepsis and septic shock. Consideration of their time courses may be more reliable than absolute levels. Clinical decision should not be based only on biomarkers but organ dysfunctions, for example, should also be taken into account.

Value of β-D-glucan and Candida albicans germ tube antibody for discriminating between Candida colonization and invasive candidiasis in patients with severe abdominal conditions

PURPOSE

To assess the value of (1→3)-β-D: -glucan (BDG), Candida albicans germ tube antibody (CAGTA), C-reactive protein (CRP), and procalcitonin (PCT) levels for the diagnosis of invasive candidiasis (IC) and for differentiating Candida spp. colonization from infection in ICU patients with severe abdominal conditions (SAC).

METHODS

Prospective study of 176 non-neutropenic patients, with SAC at ICU admission, and expected to stay at least 7 days. Surveillance cultures and BDG, CAGTA, CRP, and PCT levels were performed on the third day of ICU stay and twice a week for four consecutive weeks. Patients were grouped into invasive candidiasis (IC), Candida colonization, and neither colonized/nor infected. The classification and regression tree (CART) analysis was used to predict IC in colonized patients. The discriminatory ability of the obtained prediction rule was assessed by the area under the ROC curve (AUC).

RESULTS

The probabilities of IC were 59.3 % for the terminal node of BDG greater than 259 pg/mL and 30.8 % for BDG less than 259 pg/mL and CAGTA positivity, whereas there was a 93.9 % probability in predicting the absence of IC for BDG less than 259 pg/mL and negative CAGTA. Using a cutoff of 30 % for IC probability, the prediction rule showed 90.3 % sensitivity, 54.8 % specificity, 42.4 % positive predictive value, and 93.9 % negative predictive value with an AUC of 0.78 (95 % confidence interval 0.76-0.81). Significant differences in CRP (p = 0.411) and PCT (p = 0.179) among the studied groups were not found.

CONCLUSIONS

BDG with a positive test for CAGTA accurately differentiated Candida colonization from IC in patients with SAC, whereas CRP and PCT did not.

Sequential C-reactive protein measurements in patients with serious infections: does it help?

C-reactive protein (CRP) is a marker of inflammation traditionally used as a complementary tool to support the clinical diagnosis and as a marker of severity of disease. CRP is an acute-phase protein synthesized by the liver after stimulus by cytokines and its serum levels increase markedly within hours after the onset of infection, inflammation or tissue injury. Dynamic serial measurement of CRP has been widely used to help therapeutic decision-making. Decreasing plasma concentrations of this biomarker have been used as an indicator for resolution of infection or sepsis.

Absolute eosinophils count as a marker of mortality in patients with severe sepsis and septic shock in an intensive care unit

INTRODUCTION

Eosinophils in the circulating blood undergo apoptosis during sepsis syndromes induced by the action of certain cytokines.

OBJECTIVE

The aim of the study was to evaluate the absolute eosinophils count (EC) as a marker of mortality in severe sepsis and septic shock.

PATIENTS AND METHOD

A prospective cohort study of patients with a diagnosis of sepsis or septic shock admitted to the intensive care unit (ICU) of the Dr Gustavo Fricke Hospital between January 2008 and December 2009 was conducted. Daily EC in all patients was analyzed. Receiver operating characteristic curve analysis was used to assess the performance of the diagnostic test.

RESULTS

We studied a total of 240 patients. The median age was 62 years (interquartile range [IQR], 48-72 years), and 67 (27.9%) died. The median EC in patients who died was 43 (IQR, 14-121), whereas in surviving patients, it was 168 (IQR, 98-292) (P < .001). When the EC on the fifth day of hospital stay was assessed, an area under the curve (AUC) of 0.64 (95% confidence interval, 0.55-0.73) was observed. Eosinophils count at intensive care unit discharge showed an area under the curve of 0.81 (95% confidence interval, 0.76-0.87).

DISCUSSION

Eosinophils counts were lower in patients who died of sepsis than in those who survived, but its clinical usefulness seems limited. Their role as an indicator of clinical stability seems to be important.

C-reactive protein in community-acquired sepsis: you can teach new tricks to an old dog

Severe sepsis is a major challenge for clinicians caring for acutely ill patients. For many years, several biomarkers have been tested and proposed to improve the ability not only to diagnose but also to anticipate clinical response to antibiotics. Despite the availability of many sophisticated and novel biomarkers, current evidence demonstrates that C-reactive protein (CRP), a well-known and relatively inexpensive biomarker, is useful in the clinical setting. The sequential evaluation of plasma CRP concentrations in patients with severe sepsis and the interpretation of its patterns may allow assessments of individual prognosis and response to treatment.