Effect of Procalcitonin-Guided Treatment in Patients with Infections: a Systematic Review and Meta-Analysis

Procalcitonin to initiate or discontinue antibiotics in acute respiratory tract infections

BACKGROUND

Acute respiratory infections (ARIs) comprise a large and heterogeneous group of infections including bacterial, viral and other aetiologies. In recent years, procalcitonin - the prohormone of calcitonin - has emerged as a promising marker for the diagnosis of bacterial infections and for improving decisions about antibiotic therapy. Several randomised controlled trials (RCTs) have demonstrated the feasibility of using procalcitonin for starting and stopping antibiotics in different patient populations with acute respiratory infections and different settings ranging from primary care to emergency departments (EDs), hospital wards and intensive care units (ICUs).

OBJECTIVES

The aim of this systematic review based on individual patient data was to assess the safety and efficacy of using procalcitonin for starting or stopping antibiotics over a large range of patients with varying severity of ARIs and from different clinical settings.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2011, Issue 2) which contains the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to May 2011) and EMBASE (1974 to May 2011) to identify suitable trials.

SELECTION CRITERIA

We included RCTs of adult participants with ARIs who received an antibiotic treatment either based on a procalcitonin algorithm or usual care/guidelines. Trials were excluded if they exclusively focused on paediatric patients or if they used procalcitonin for another purpose than to guide initiation and duration of antibiotic treatment.

DATA COLLECTION AND ANALYSIS

Two teams of review authors independently evaluated the methodology and extracted data from primary studies. The primary endpoints were all-cause mortality and treatment failure at 30 days. For the primary care setting, treatment failure was defined as death, hospitalisation, ARI-specific complications, recurrent or worsening infection, and patients reporting any symptoms of an ongoing respiratory infection at follow-up. For the ED setting, treatment failure was defined as death, ICU admission, re-hospitalisation after index hospital discharge, ARI-associated complications, and recurrent or worsening infection within 30 days of follow-up. For the ICU setting, treatment failure was defined as death within 30 days of follow-up. Secondary endpoints were antibiotic use (initiation of antibiotics, duration of antibiotics and total exposure to antibiotics (total amount of antibiotic days divided by total number of patients)), length of hospital stay for hospitalised patients, length of ICU stay for critically ill patients, and number of days with restricted activities within 14 days after randomisation for primary care patients.For the two co-primary endpoints of all-cause mortality and treatment failure, we calculated odds ratios (ORs) and 95% confidence intervals (CIs) using multivariable hierarchical logistic regression. The hierarchical regression model was adjusted for age and clinical diagnosis as fixed-effect. The different trials were added as random-effects into the model. We fitted corresponding linear regression models for antibiotic use. We conducted sensitivity analyses stratified by clinical setting and ARI diagnosis to assess the consistency of our results.

MAIN RESULTS

We included 14 trials with 4221 participants. There were 118 deaths in 2085 patients (5.7%) assigned to procalcitonin groups compared to 134 deaths in 2126 control patients (6.3%) (adjusted OR 0.94, 95% CI 0.71 to 1.23). Treatment failure occurred in 398 procalcitonin group patients (19.1%) and in 466 control patients (21.9%). Procalcitonin guidance was not associated with increased mortality or treatment failure in any clinical setting, or ARI diagnosis. These results proved robust in various sensitivity analyses. Total antibiotic exposure was significantly reduced overall (median (interquartile range) from 8 (5 to 12) to 4 (0 to 8) days; adjusted difference in days, -3.47, 95% CI -3.78 to -3.17, and across all the different clinical settings and diagnoses.

AUTHORS' CONCLUSIONS

Use of procalcitonin to guide initiation and duration of antibiotic treatment in patients with ARI was not associated with higher mortality rates or treatment failure. Antibiotic consumption was significantly reduced across different clinical settings and ARI diagnoses. Further high-quality research is needed to confirm the safety of this approach for non-European countries and patients in intensive care. Moreover, future studies should also establish cost-effectiveness by considering country-specific costs of procalcitonin measurement and potential savings in consumption of antibiotics and other healthcare resources, as well as secondary cost savings due to lower risk of side effects and reduced antimicrobial resistance.

Procalcitonin to guide initiation and duration of antibiotic treatment in acute respiratory infections: an individual patient data meta-analysis

BACKGROUND

Procalcitonin algorithms may reduce antibiotic use for acute respiratory tract infections (ARIs). We undertook an individual patient data meta-analysis to assess safety of this approach in different ARI diagnoses and different clinical settings.

METHODS

We identified clinical trials in which patients with ARI were assigned to receive antibiotics based on a procalcitonin algorithm or usual care by searching the Cochrane Register, MEDLINE, and EMBASE. Individual patient data from 4221 adults with ARIs in 14 trials were verified and reanalyzed to assess risk of mortality and treatment failure-overall and within different clinical settings and types of ARIs.

RESULTS

Overall, there were 118 deaths in 2085 patients (5.7%) assigned to procalcitonin groups compared with 134 deaths in 2126 control patients (6.3%; adjusted odds ratio, 0.94; 95% confidence interval CI, .71-1.23)]. Treatment failure occurred in 398 procalcitonin group patients (19.1%) and in 466 control patients (21.9%; adjusted odds ratio, 0.82; 95% CI, .71-.97). Procalcitonin guidance was not associated with increased mortality or treatment failure in any clinical setting or ARI diagnosis. Total antibiotic exposure per patient was significantly reduced overall (median [interquartile range], from 8 [5-12] to 4 [0-8] days; adjusted difference in days, -3.47 [95% CI, -3.78 to -3.17]) and across all clinical settings and ARI diagnoses.

CONCLUSIONS

Use of procalcitonin to guide initiation and duration of antibiotic treatment in patients with ARIs was effective in reducing antibiotic exposure across settings without an increase in the risk of mortality or treatment failure. Further high-quality trials are needed in critical-care patients.

The role of biomarkers in low respiratory tract infections

Low respiratory tract infections (LRTI) represent the leading infectious cause of death worldwide and account for substantial use of healthcare resources. Physicians must adopt practices focused on improving outcomes and serum biomarker can help them in the management of patients with LRTI. Several studies have been carried out or are currently ongoing to evaluate the role of various biomarkers for the differential diagnosis, definition of prognosis, treatment and duration of antibiotic therapy in respiratory infections. The objective of this position paper of the Italian Society of Respiratory Diseases (SIMER) is to provide evidence-based recommendations for the use of biomarkers in routine clinical practice in the management of adult patients with LRTI. These guidelines capture the use of biomarkers both outside and inside the hospital, focused on community-acquired pneumonia, acute exacerbations of chronic obstructive pulmonary disease, hospital-acquired and ventilator-acquired pneumonia.

The use of a standardized PCT-algorithm reduces costs in intensive care in septic patients - a DRG-based simulation model

INTRODUCTION

The management of bloodstream infections especially sepsis is a difficult task. An optimal antibiotic therapy (ABX) is paramount for success. Procalcitonin (PCT) is a well investigated biomarker that allows close monitoring of the infection and management of ABX. It has proven to be a cost-efficient diagnostic tool. In Diagnoses Related Groups (DRG) based reimbursement systems, hospitals get only a fixed amount of money for certain treatments. Thus it's very important to obtain an optimal balance of clinical treatment and resource consumption namely the length of stay in hospital and especially in the Intensive Care Unit (ICU). We investigated which economic effects an optimized PCT-based algorithm for antibiotic management could have.

MATERIALS AND METHODS

We collected inpatient episode data from 16 hospitals. These data contain administrative and clinical information such as length of stay, days in the ICU or diagnoses and procedures. From various RCTs and reviews there are different algorithms for the use of PCT to manage ABX published. Moreover RCTs and meta-analyses have proven possible savings in days of ABX (ABD) and length of stay in ICU (ICUD). As the meta-analyses use studies on different patient populations (pneumonia, sepsis, other bacterial infections), we undertook a short meta-analyses of 6 relevant studies investigating in sepsis or ventilator associated pneumonia (VAP). From this analyses we obtained savings in ABD and ICUD by calculating the weighted mean differences. Then we designed a new PCT-based algorithm using results from two very recent reviews. The algorithm contains evidence from several studies. From the patient data we calculated cost estimates using German National standard costing information for the German G-DRG system. We developed a simulation model where the possible savings and the extra costs for (in average) 8 PCT tests due to our algorithm were brought into equation.

RESULTS

We calculated ABD savings of 4 days and ICUD reductions of -1.8 days. Our algorithm contains recommendations for ABX onset (PCT ≥ 0.5 ng/ml), validation whether ABX is appropriate or not (Delta from day 2 to day 3 ≥ 30% indicates inappropriate ABX) and recommendations for discontinuing ABX (PCT ≤ 0.25 ng/ml). We received 278,264 episode datasets where we identified by computer-based selection 3,263 cases with sepsis. After excluding cases with length of stay (LOS) too short to achieve the intended savings, we ended with 1,312 cases with ICUD and 268 cases without ICUD. Average length of stay of ICU-patients was 27.7 ± 25.7 days and for Non-ICU patients 17.5 ± 14.6 days respectively. ICU patients had an average of 8.8 ± 8.7 ICUD. - After applying the simulation model on this population we calculated possible savings of Euro -1,163,000 for ICU-patients and Euro -36,512 for Non-ICU patients.

DISCUSSION

Our findings concerning the savings from the reduction of ABD are consistent with other publications. Savings ICUD had never been economically evaluated so far. Our algorithm is able to possibly set a new standard in PCT-based ABX. However the findings are based on data modelling. The algorithm will be implemented in 5-10 hospitals in 2012 and effects in clinical reality measured 6 months after implementation.

CONCLUSION

Managing sepsis with daily monitoring of PCT using our refined algorithm is suitable to save substantial costs in hospitals. Implementation in clinical routine settings will show how much of the calculated effect will be achieved in reality.

Clinical review: flow cytometry perspectives in the ICU - from diagnosis of infection to monitoring of injury-induced immune dysfunctions

Septic syndromes represent a major healthcare problem worldwide. Clinical and experimental evidence indicates that septic patients rapidly present with numerous compromised immune functions. Although flow cytometry remains a relatively confidential diagnostic tool, it could be useful at every step of ICU patient management. Indeed, neutrophil CD64 expression is a sensitive and specific tool for diagnosis of sepsis in adults, neonates and children. Diminished monocyte HLA-DR expression is a reliable marker for the development of monocyte anergy, prediction of secondary nosocomial infection and death in critically ill patients. Finally, the measurement of an increased CD4⁺CD25⁺CD127^low regulatory T-cell percentage may represent a reliable marker for the diagnosis of lymphocyte dysfunctions in these patients. Ideally, these biomarkers should be part of a panel helping to define ICU patients' immune status. The potential of flow cytometry is further illustrated by use of the biomarkers listed above as stratification tools in preliminary clinical studies. Importantly, many other markers of immune dysfunctions are currently under development that could further enable the administration of targeted individualized therapy in ICU patients. The next critical step would be to use these standardized flow cytometry protocols in large multicentric clinical trials testing individualized immunotherapy.

Inflammatory biomarkers for the diagnosis, monitoring and follow-up of community-acquired pneumonia: clinical evidence and perspectives

Community-acquired pneumonia (CAP) is defined as an infection of the alveolar or gas-exchanging portions of the lungs occurring outside the hospital, with clinical symptoms accompanied by the presence of an infiltrate in the chest radiograph. Due to the high prevalence and the large demand of healthcare resources, an accurate clinical and therapeutic decision making is crucial in patients with CAP. As such, there is increasing interest on the use of traditional and innovative biomarkers such as procalcitonin (PCT) and C-reactive protein (CRP). At variance with other traditional inflammatory and innovative biomarkers, PCT might help limiting unnecessary antibiotic use, reduce bacterial resistance and decrease medical costs and drug-related adverse events. PCT however carries some additional advantages over CRP, such as the greater specificity for infections and a more narrow range of normal concentrations.

Meta-analysis and systematic review of procalcitonin-guided therapy in respiratory tract infections

Circulating procalcitonin (PCT) is a biomarker that can be used in diagnosing bacterial infections. We performed a quantitative meta-analysis of available randomized controlled trials to determine whether antibiotic therapy based on PCT measurements alters clinical outcomes and antibiotic use in patients with lower respiratory tract infections. We identified studies through MEDLINE (1996 to 2010), the ISI Web of Knowledge (1996 to 2010), and Ovid. Studies that met our criteria were prospective, randomized controlled trials involving patients with respiratory tract infections. Outcomes of mortality, intensive care unit (ICU) admission, length of hospital stay, number of antibiotic prescriptions, and duration of antibiotic treatment were evaluated. Eight studies randomizing 3,431 patients met our criteria for inclusion. Pooled analysis showed a significant reduction in number of antibiotic prescriptions and duration of antibiotic use in patients with PCT-guided antibiotic treatment compared to standard therapy. In addition, the use of PCT-guided antibiotic therapy did not impact mortality, ICU admission, or length of hospital stay in these studies. A high degree of heterogeneity was identified in 3 of 5 outcomes that were evaluated, and sensitivity analysis indicated that heterogeneity was decreased among studies using the same PCT-based treatment algorithm. In conclusion, PCT-guided antibiotic therapy in patients with respiratory tract infections appears to reduce antibiotic use without affecting overall mortality or length of stay in the hospital.

Procalcitonin for reduced antibiotic exposure in the critical care setting: a systematic review and an economic evaluation

OBJECTIVE

Procalcitonin may be associated with reduced antibiotic usage compared to usual care. However, individual randomized controlled trials testing this hypothesis were too small to rule out harm, and the full cost-benefit of this strategy has not been evaluated. The purpose of this analysis was to evaluate the effect of a procalcitonin-guided antibiotic strategy on clinical and economic outcomes.

INTERVENTIONS

The use of procalcitonin-guided antibiotic therapy.

METHODS AND MAIN RESULTS

We searched computerized databases, reference lists of pertinent articles, and personal files. We included randomized controlled trials conducted in the intensive care unit that compared a procalcitonin-guided strategy to usual care and reported on antibiotic utilization and clinically important outcomes. Results were qualitatively and quantitatively summarized. On the basis of no effect in hospital mortality or hospital length of stay, a cost or cost-minimization analysis was conducted using the costs of procalcitonin testing and antibiotic acquisition and administration. Costs were determined from the literature and are reported in 2009 Canadian dollars. Five articles met the inclusion criteria. Procalcitonin-guided strategies were associated with a significant reduction in antibiotic use (weighted mean difference -2.14 days, 95% confidence interval -2.51 to -1.78, p < .00001). No effect was seen of a procalcitonin-guided strategy on hospital mortality (risk ratio 1.06, 95% confidence interval 0.86-1.30, p = .59; risk difference 0.01, 95% confidence interval -0.04 to +0.07, p = .61) and intensive care unit and hospital lengths of stay. The cost model revealed that, for the base case scenario (daily price of procalcitonin Can$49.42, 6 days of procalcitonin measurement, and 2-day difference in antibiotic treatment between procalcitonin-guided therapy and usual care), the point at which the cost of testing equals the cost of antibiotics saved is when daily antibiotics cost Can$148.26 (ranging between Can$59.30 and Can$296.52 on the basis of different assumptions in sensitivity analyses).

CONCLUSIONS

Procalcitonin-guided antibiotic therapy is associated with a reduction in antibiotic usage that, under certain assumptions, may reduce overall costs of care. However, the overall estimate cannot rule out a 7% increase in hospital mortality.

Measurement of granulocyte maturation may improve the early diagnosis of the septic state

BACKGROUND

Sepsis is a costly diagnosis in hospitalized patients. Failure to diagnose sepsis in a timely manner creates a potential financial and safety hazard. The use of transthyretin, C-reactive protein and procalcitonin measurement as early markers of systemic inflammatory response syndrome (SIRS) and sepsis in association with admission of emergency department patients to the intensive care unit (ICU) has been studied. In these studies the SIRS criteria as well as the use of an elevated neutrophil count with granulocyte precursors (left shift) have proved to be problematic. Despite the validity of procalcitonin measurement (PCT, Brahms) in the early diagnosis of SIRS the cost and time for testing are limiting considerations. Immature granulocyte (IG) measurement has been proposed as a more readily available indicator of the presence of granulocyte precursors (left shift).

METHODS

This study calibrates and validates the measurement of granulocyte maturation [Immature granulocytes (IG)] to the identification of sepsis, a study carried out on a Sysmex Analyzer, model XE 2100 (Kobe, Japan). The Sysmex IG parameter is a crucial measure of immature granulocyte counts and includes metamyelocytes and myelocytes, but not band neutrophils.

RESULTS AND CONCLUSIONS

We found agreement with previous work that designated an IG measurement cut-off of 3.2 as optimal. The analysis was then carried a step further with a multivariable discriminator.

Usefulness of consecutive biomarkers measurement in the management of community-acquired pneumonia

The aim of this study was to investigate whether procalcitonin (PCT), neopterin, C-reactive protein (CRP), and mid regional pro-atrial natriuretic peptide (MR-proANP) levels at admission and during the clinical course can be useful for the management of patients with pneumonia. The study population consisted of 75 patients with clinical and radiological diagnosis of pneumonia. Serum samples were collected at admission and during hospitalization. Complications were defined as intensive care unit (ICU) admission or death. The levels of PCT were significantly higher in pneumonia of definite bacterial origin in comparison to probable bacterial or unknown origin. The PCT levels were higher in pneumococcal pneumonia. The PCT and MR-proANP levels increased significantly according to the Pneumonia Severity Index (PSI). All biomarkers levels are higher in patients developing complications and who were dying. The serial levels of MR-proANP remain significantly elevated in patients developing complications and in patients classified in PSI and CURB-65 risk groups. In patients not developing complications, there is a significant decrease in the PCT levels. PCT can be useful for identifying pneumonia etiology. PCT and MR-proANP levels correlate with pneumonia severity rules. PCT and MR-proANP serial measurements can be useful for predicting short-term prognosis. Systemic biomarkers can provide additional information regarding clinical evolution, because these are dynamic and can be measured daily.

Biomarkers for ventilator-associated pneumonia: review of the literature

OBJECTIVE

Ventilator-associated pneumonia (VAP) contributes significantly to morbidity and mortality in critically ill patients, but it can be difficult to diagnose. Clinical criteria, Clinical Pulmonary Infection Score, and quantitative culture of bronchoalveolar lavage have been used to distinguish between patients who are likely positive (sensitivity) and patients who are likely negative (specificity). Despite these test methods, patients continue to be misclassified. False-positive results may lead to inappropriate antibiotic use in patients. For those misclassified as test negative, appropriate treatment may be delayed. Biomarkers have been suggested as another method to enhance the ability to predict VAP. This article analyzes the evidence for the usefulness of 3 biomarkers that have been proposed as possible biomarkers of VAP: soluble triggering receptor expressed on myeloid type 1 cells, procalcitonin, and C-reactive protein.

METHODS

A Medline search was conducted for the years between 1990 and 2009 to locate articles on the subject of biomarkers for predicting VAP in critically ill adult patients.

RESULTS

Analysis of the literature does not currently support a clinical role for these biomarkers in predicting VAP. Variations in the diagnostic methods, antimicrobial use, cutoff values, and patient populations limit comparisons among the studies.

CONCLUSION

Recommendations are offered to strengthen and standardize methods in future studies to clarify the utility of biomarkers for predicting VAP in specific patient populations.

Value of procalcitonin, C-reactive protein, and neopterin in exacerbations of chronic obstructive pulmonary disease

Objective:

The identification of biological markers in order to assess different aspects of COPD is an area of growing interest. The objective of this study was to investigate whether levels of procalcitonin (PCT), C-reactive protein (CRP), and neopterin in COPD patients could be useful in identifying the etiological origin of the exacerbation and assessing its prognosis.

Methods:

We included 318 consecutive COPD patients: 46 in a stable phase, 217 undergoing an exacerbation, and 55 with pneumonia. A serum sample was collected from each patient at the time of being included in the study. A second sample was also collected 1 month later from 23 patients in the exacerbation group. We compared the characteristics, biomarker levels, microbiological findings, and prognosis in each patient group. PCT and CRP were measured using an immunofluorescence assay. Neopterin levels were measured using a competitive immunoassay.

Results:

PCT and CRP showed significant differences among the three patient groups, being higher in patients with pneumonia, followed by patients with exacerbation (P < 0.0001). For the 23 patients with paired samples, PCT and CRP levels decreased 1 month after the exacerbation episode, while neopterin increased. Neopterin showed significantly lower levels in exacerbations with isolation of pathogenic bacteria, but no differences were found for PCT and CRP. No significant differences were found when comparing biomarker levels according to the Gram result: PCT (P = 0.191), CRP (P = 0.080), and neopterin (P = 0.109). However, median values of PCT and CRP were high for Streptococcus pneumoniae, Staphylococcus aureus, and enterobacteria. All biomarkers were higher in patients who died within 1 month after the sample collection than in patients who died later on.

Conclusions:

According to our results, biomarker levels vary depending on the clinical status. However, the identification of the etiology of infectious exacerbation by means of circulating biomarkers is encouraging, but its main disadvantage is the absence of a microbiological gold standard, to definitively demonstrate their value. High biomarker levels during an exacerbation episode correlate with the short-term prognosis, and therefore their measurement can be useful for COPD management.

Impact of an antibiotic restriction program on antibiotic utilization in the treatment of community-acquired pneumonia in a Veterans Affairs Medical Center

PURPOSE

The impact of an antibiotic restriction program (ARP) on the patterns of antibiotic use in the treatment of community-acquired pneumonia (CAP) was examined. We also evaluated the association between the ARP and the length of hospital stay in regard to CAP treatment and cost savings associated with the implementation of the ARP.

METHODS

A retrospective cohort study of patients admitted with CAP was conducted during two 6-month periods, one prior to the ARP and one after the ARP. The health system's computerized patient record system (CPRS) was used to obtain demographics, length of hospital stays, readmission rates, blood culture results, co-morbidities, antibiotic use, and durations of therapy. A total of 130 patients met the inclusion criteria for the final analyses. Average drug costs, employee salaries, and the cost of laboratory procedures were used to assess cost savings associated with the ARP.

RESULTS

From a total of 132 antibiotics that were ordered to treat CAP in the pre-ARP period, 28 were restricted (21.2%). However, the number of restricted antibiotics ordered was significantly reduced to 12 out of 114 (10.2%) antibiotics ordered in the post-ARP period (P = 0.024). In post-ARP implementation, the mean length of hospital stay was also significantly reduced from 7.6 to 5.8 days (P = 0.017), and although not statistically significant, the 30-day readmission rates declined from 16.9 to 6.2% (P = 0.097). The ARP was also associated with a saving of $943 per patient treated for CAP.

CONCLUSIONS

In addition to a decrease in the antibiotic utilization and the mean length of hospital stay, the ARP may have yielded cost savings and reduced the readmission rates for those patients admitted and treated for CAP.

Is procalcitonin a marker of invasive bacterial infection in acute sickle-cell vaso-occlusive crisis?

Fever is often present during painful vaso-occlusive crisis (VOC) in sickle-cell disease (SCD), but does not always indicate infection. The aim of our study was to test procalcitonin as a marker of invasive bacterial infection in VOC. Consecutive SCD adults hospitalized for VOC were included. Data were collected at admission and within 24 h after the onset of fever. We distinguished patients with clinically defined and microbiologically documented invasive bacterial infection from patients with no evidence of invasive bacterial infection and who fared well without antibiotics. One hundred and twelve patients were enrolled (61% females, median age 23 years, 88% homozygous SCD). All patients with procalcitonin (PCT) level ≥1 μg/L had an invasive bacterial infection, but two patients (33%) with an invasive bacterial infection had a PCT level <1 μg/L. High levels of PCT indicate invasive bacterial infection. However, a single low PCT level without follow-up measurement cannot rule out an invasive bacterial infection and should not withhold the prescription of antibiotics.

Flow cytometry developments and perspectives in clinical studies: examples in ICU patients

Septic syndromes represent a major, although largely under-recognized, healthcare problem worldwide accounting for thousands of deaths every year. Although flow cytometry (FCM) remains a relatively confidential diagnostic tool, it is useful at every step of intensive care unit (ICU) patients' management. This review will focus on biomarkers measurable by FCM on a routine standardized basis and usable for the diagnosis of sepsis and for prediction of adverse outcome, occurrence of secondary nosocomial infections or guidance of putative immunotherapy relative to innate and adaptive immune dysfunctions in ICU patients. Regarding early diagnosis of infection, neutrophil CD64 has been shown to be a highly sensitive and specific marker for systemic infection and sepsis in adults, neonates, and children. A diminished monocyte HLA-DR expression is a reliable marker for the development of monocyte anergy, secondary nosocomial infection, and death in critically ill patients. Finally, the measurement of an increased CD4(+)CD25(+)CD127(low) regulatory T cell percentage may represent a reliable marker for the diagnosis of lymphocyte dysfunctions in these patients. These stainings can be performed using lyse-no-wash methods and results are available within 1 h. Ideally, these biomarkers should be part of a panel helping to define ICU patients' immune status. In the specific clinical context of ICU patients' monitoring, the increasing potential of FCM is further illustrated by the use of the biomarkers listed above as stratification tools in preliminary clinical studies. The next critical step is to use these standardized FCM protocols in large multicentric clinical trials testing individualized immunotherapy. Importantly, many other markers of immune dysfunction are currently under development that could further enable the administration of targeted individualized therapy in ICU patients.