Plasma level of soluble urokinase-type plasminogen activator receptor as a predictor of disease severity and case fatality in patients with bacteraemia: a prospective cohort study

Soluble urokinase-type plasminogen activator receptor in patients with suspected infection in the emergency room: a prospective cohort study

OBJECTIVES

The soluble form of urokinase-type plasminogen activator (suPAR) was evaluated as an early prognostic marker of sepsis in patients with suspected infection.

DESIGN

A single-centre prospective cohort study.

METHODS

The cohort comprised 539 patients in the emergency department with suspected infection: 59 without systemic inflammatory response syndrome (SIRS) and without bacterial infection (group 1), 68 with bacterial infection and without SIRS (group 2), 54 with SIRS and without bacterial infection (group 3), 309 with sepsis (SIRS and bacterial infection) and without organ failure (group 4) and 49 with severe sepsis (SIRS, bacterial infection and organ failure) (group 5). suPAR was measured on admission using a commercial solid-phase enzyme-linked immunosorbent assay.

RESULTS

The median soluble form of the receptor (suPAR) concentrations in groups 1-5 were 4.7, 5.0, 4.4, 4.8 and 7.9 ng mL(-1) , respectively (P < 0.001). The levels were significantly higher in nonsurvivors compared with survivors (8.3 vs. 4.9 ng mL(-1) , P < 0.001) and in patients with severe sepsis (group 5) compared with those in the other groups (7.9 vs. 4.8 ng mL(-1) , P < 0.001). Area under the receiver operating characteristics curve (AUC(ROC) ) for the prediction of case fatality was 0.79 (95% confidence interval [CI]: 0.72-0.86, P < 0.0001) and 0.75 for severe sepsis (95% CI: 0.68-0.81, P < 0.0001). At a cut-off level of 6.4 ng mL(-1) , suPAR had 76% sensitivity and 69% specificity for fatal disease; at a cut-off level of 6.6 ng mL(-1) , the sensitivity and specificity for severe sepsis were 67% and 72%, respectively. In multivariate models, high suPAR remained an independent predictor of case fatality and severe sepsis after adjusting for potential confounders.

CONCLUSIONS

A high suPAR level predicts case fatality and severe sepsis in patients with suspected infection.

Soluble urokinase plasminogen activator receptor suPAR as a marker for inflammation in pediatric inflammatory bowel disease

OBJECTIVE

In inflammatory bowel disease (IBD), more means to monitor early therapeutic response are needed. In pediatric IBD, blood inflammatory markers erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) may be low in 10 to 20% of patients with severe disease. Recently, soluble urokinase plasminogen activator receptor (suPAR) was described as a potential blood inflammatory marker in adult IBD.

METHODS

We tested the performance of suPAR by the start of therapy with glucocorticoids (n = 19) or TNF-α-antagonist (n = 16) in pediatric IBD (Crohn's disease n = 19, ulcerative colitis (UC) n = 16).

RESULTS

The levels of suPAR were low in both patient groups studied. There was no difference in the values regarding the presence of Crohn's disease or ulcerative colitis. Thus, all analyses were performed on the entire sample set. Glucocorticoid therapy, however, resulted in a significant decline in suPAR levels from a median of 3.06 to 2.54 ng/ml (p < 0.01). In contrast, TNF-α-antagonist had no effect. The suPAR levels did not associate with ESR or CRP or fecal calprotectin (FC).

CONCLUSIONS

In pediatric IBD, the suPAR levels in blood are low and do not reflect the level of intestinal inflammation assessed with FC. The introduction of corticoids, however, results in a decline of suPAR levels in blood but not reflect therapeutic response to TNF-α-antagonist. Thus, suPAR is of limited value in assessing systemic inflammatory responses in pediatric IBD.

Utility of the plasma level of suPAR in monitoring risk of mortality during TB treatment

Objective

To investigate whether changes in the plasma level of soluble urokinase plasminogen activator receptor (suPAR) can be used to monitor tuberculosis (TB) treatment efficacy.

Design

This prospective cohort study included 278 patients diagnosed with active pulmonary TB and followed throughout the 8-month treatment period.

Results

Mortality during treatment was higher in the highest inclusion quartile of suPAR (23%) compared to the lowest three quartiles (7%), the risk ratio being 3.1 (95% CI 1.65–6.07). No association between early smear conversion and subsequent mortality or inclusion suPAR was observed. After 1 and 2 months of treatment, an increase in suPAR compared to at diagnosis was associated with a Mortality Rate Ratio (MRR) of 4.5 (95%CI: 1.45–14.1) and 2.1 (95%CI 0.62–6.82), respectively, for the remaining treatment period.

Conclusions

The present study confirmed that elevated suPAR level at time of initiation of TB treatment is associated with increased risk of mortality. Furthermore, increased suPAR levels after one month of treatment was associated with increased risk of mortality during the remaining 7-month treatment period.

Risk assessment in sepsis: a new prognostication rule by APACHE II score and serum soluble urokinase plasminogen activator receptor

INTRODUCTION

Early risk assessment is the mainstay of management of patients with sepsis. APACHE II is the gold standard prognostic stratification system. A prediction rule that aimed to improve prognostication by APACHE II with the application of serum suPAR (soluble urokinase plasminogen activator receptor) is developed.

METHODS

A prospective study cohort enrolled 1914 patients with sepsis including 62.2% with sepsis and 37.8% with severe sepsis/septic shock. Serum suPAR was measured in samples drawn after diagnosis by an enzyme-immunoabsorbent assay; in 367 patients sequential measurements were performed. After ROC analysis and multivariate logistic regression analysis a prediction rule for risk was developed. The rule was validated in a double-blind fashion by an independent confirmation cohort of 196 sepsis patients, predominantly severe sepsis/septic shock patients, from Sweden.

RESULTS

Serum suPAR remained stable within survivors and non-survivors for 10 days. Regression analysis showed that APACHE II ≥ 17 and suPAR ≥ 12 ng/ml were independently associated with unfavorable outcome. Four strata of risk were identified: i) APACHE II <17 and suPAR <12 ng/ml with mortality 5.5%; ii) APACHE II < 17 and suPAR ≥ 12 ng/ml with mortality 17.4%; iii) APACHE II ≥ 17 and suPAR <12 ng/ml with mortality 37.4%; and iv) APACHE II ≥ 17 and suPAR ≥ 12 ng/ml with mortality 51.7%. This prediction rule was confirmed by the Swedish cohort.

CONCLUSIONS

A novel prediction rule with four levels of risk in sepsis based on APACHE II score and serum suPAR is proposed. Prognostication by this rule is confirmed by an independent cohort.

Plasma suPAR levels are associated with mortality, admission time, and Charlson Comorbidity Index in the acutely admitted medical patient: a prospective observational study

INTRODUCTION

Soluble urokinase plasminogen activator receptor (suPAR) is the soluble form of the membrane-bound receptor (uPAR) expressed predominantly on various immune cells. Elevated plasma suPAR concentration is associated with increased mortality in various patient groups, and it is speculated that suPAR is a low-grade inflammation marker reflecting on disease severity. The aim of this prospective observational study was to determine if the plasma concentration of suPAR is associated with admission time, re-admission, disease severity/Charlson Comorbidity Index Score, and mortality.

METHODS

We included 543 patients with various diseases from a Danish Acute Medical Unit during a two month period. A triage unit ensured that only medical patients were admitted to the Acute Medical Unit. SuPAR was measured on plasma samples drawn upon admission. Patients were followed-up for three months after inclusion by their unique civil registry number and using Danish registries to determine admission times, readmissions, International Classification of Diseases, 10th Edition (ICD-10) diagnoses, and mortality. Statistical analysis was used to determine suPAR's association with these endpoints.

RESULTS

Increased suPAR was significantly associated with 90-day mortality (4.87 ng/ml in survivors versus 7.29 ng/ml in non-survivors, P < 0.0001), higher Charlson Score (P < 0.0001), and longer admission time (P < 0.0001), but not with readmissions. The association with mortality remained when adjusting for age, sex, C-reactive protein (CRP), and Charlson Score. Furthermore, among the various Charlson Score disease groups, suPAR was significantly higher in those with diabetes, cancer, cardiovascular disease, and liver disease compared to those without comorbidities.

CONCLUSIONS

SuPAR is a marker of disease severity, admission time, and risk of mortality in a heterogeneous cohort of patients with a variety of diseases. The independent value of suPAR suggests it could be of value in prognostic algorithms.

Usefulness of suPAR as a biological marker in patients with systemic inflammation or infection: a systematic review

Purpose

Systemic levels of soluble urokinase-type plasminogen activator receptor (suPAR) positively correlate with the activation level of the immune system. We reviewed the usefulness of systemic levels of suPAR in the care of critically ill patients with sepsis, SIRS, and bacteremia, focusing on its diagnostic and prognostic value.

Methods

A PubMed search on suPAR was conducted, including manual cross-referencing. The list of papers was narrowed to original studies of critically ill patients. Ten papers on original studies of critically ill patients were identified that report on suPAR in sepsis, SIRS, or bacteremia.

Results

Systematic levels of suPAR have little diagnostic value in critically ill patients with sepsis, SIRS, or bacteremia. Systemic levels of suPAR, however, have superior prognostic power over other commonly used biological markers in these patients. Mortality prediction by other biological markers or severity-of-disease classification system scores improves when combining them with suPAR. Systemic levels of suPAR correlate positively with markers of organ dysfunction and severity-of-disease classification system scores. Finally, systemic levels of suPAR remain elevated for prolonged periods after admission and only tend to decline after several weeks. Notably, the type of assay used to measure suPAR as well as the age of the patients and underlying disease affect systemic levels of suPAR.

Conclusions

The diagnostic value of suPAR is low in patients with sepsis. Systemic levels of suPAR have prognostic value, and may add to prognostication of patients with sepsis or SIRS complementing severity-of-disease classification systems and other biological markers.

Immunoregulatory protein profiles of necrotizing enterocolitis versus spontaneous intestinal perforation in preterm infants

Necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP) are the most common acute surgical emergencies associated with high morbidity and mortality in preterm infants. We aimed to compare the profiles of immunoregulatory proteins and identify novel mediators in plasma of NEC and SIP infants. We also investigated the expression of target genes in resected intestinal tissues and an enterocyte cell line. Using Cytokine Antibody Array assay, we reported the first comparative profiles of immunoregulatory proteins in plasma of NEC and SIP infants, and showed that dysregulated proteins belonged to functionally diversified categories, including pro- and anti-inflammation, angiogenesis, cell growth, wound healing, anti-apoptosis, cell adhesion and extracellular matrix reorganization. Validation by ELISA confirmed significantly higher concentrations of interleukin (IL)-6, angiopoietin (Ang)-2, soluble type II interleukin-1 receptor (sIL-1RII), and soluble urokinase-type plasminogen activator receptor (suPAR) in NEC infants compared with gestational age-matched control, and a lower level of an epidermal growth factor receptor, secreted form of receptor tyrosine-protein kinase ErbB3 (sErbB3), compared with SIP infants. mRNA expressions of IL1-RII and uPAR were up-regulated in resected bowel tissues from NEC infants, indicating that immunoregulation also occurred at the cellular level. In FHs-74 Int cells, Ang-2, IL1-RII and uPAR mRNA expressions were significantly induced by the combined treatment with lipopolysaccharide (LPS) and platelet activating factor (PAF). Our study provided plasmatic signatures of immunoregulatory proteins in NEC and SIP infants, and demonstrated involvement of multiple functional pathways. The magnitude of changes in these proteins was significantly more extensive in NEC infants, reflecting the different nature of injury and/or severity of inflammation. We speculate that dysregulation of IL-6, Ang-2, IL-1RII and uPAR occurred at both systemic and cellular levels, and probably mediated via LPS and endogeneous PAF signals. Such exaggerated immunologic responses may account for the high morbidity and mortality in NEC compared with SIP patients.

The Prognostic Value of suPAR Compared to Other Inflammatory Markers in Patients with Severe Sepsis

It has been suggested that soluble urokinase plasminogen activator (suPAR) can be used as a marker of disease severity and risk of mortality in sepsis. The aim with the present study was to compare plasma levels of suPAR in patients with severe sepsis to control subjects and correlate it with the level of inflammatory activation, severity and mortality. Samples were collected from 27 sepsis patients at the intensive care unit (ICU), Lund, Sweden; 90-day mortalities were registered. The suPAR level was significantly elevated in sepsis patients compared to controls, but not significantly higher in nonsurvivors than survivors. Plasma levels of suPAR did correlate weakly with the SOFA score and myeloperoxidase (MPO) but not with CRP, PCT, IL-6 or IL-10 in patients with severe sepsis. The weak correlation between suPAR and other inflammatory markers might suggest that suPAR reflects general activation of the immune system rather than exerting inflammatory actions.

Current management of sepsis in critically ill adult patients

Severe sepsis is a common occurrence in critically ill patients and a major cause of morbidity and mortality in this population. Management relies on the early identification and treatment of the underlying causative infection, adequate and rapid hemodynamic resuscitation, support of associated organ failure and modulation of the immune response with drotrecogin alfa (activated) when it is not contraindicated, and corticosteroids in severe septic shock. We will review current approaches to each of these categories.

suPAR as a prognostic biomarker in sepsis

Sepsis is the clinical syndrome derived from the host response to an infection and severe sepsis is the leading cause of death in critically ill patients. Several biomarkers have been tested for use in diagnosis and prognostication in patients with sepsis. Soluble urokinase-type plasminogen activator receptor (suPAR) levels are increased in various infectious diseases, in the blood and also in other tissues. However, the diagnostic value of suPAR in sepsis has not been well defined, especially compared to other more established biomarkers, such as C-reactive protein (CRP) and procalcitonin (PCT). On the other hand, suPAR levels have been shown to predict outcome in various kinds of bacteremia and recent data suggest they may have predictive value, similar to that of severity scores, in critically ill patients. This narrative review provides a descriptive overview of the clinical value of this biomarker in the diagnosis, prognosis and therapeutic guidance of sepsis.

Why high suPAR is not super--diagnostic, prognostic and potential pathogenic properties of a novel biomarker in the ICU

The soluble urokinase plasminogen activator receptor (suPAR) has been suggested as a biomarker that reflects immune cell activation. In critically ill patients, several independent investigations have reported elevated suPAR in conditions of systemic inflammatory response syndrome (SIRS), bacteriemia, sepsis, and septic shock, in which high circulating suPAR levels indicated an unfavorable prognosis. In a prospective cohort study in this issue of Critical Care, suPAR levels were detected in bronchoalveolar lavage (BAL) and identified inhalation injury. High systemic levels indicated an adverse prognosis. This study expands our knowledge of the diagnostic power of suPAR, confirms its prognostic value, and raises the demand for future studies investigating the pathogenic involvement of suPAR.

Soluble urokinase-type plasminogen activator receptor levels in patients with burn injuries and inhalation trauma requiring mechanical ventilation: an observational cohort study

Introduction

Soluble urokinase-type plasminogen activator receptor (suPAR) has been proposed as a biologic marker of fibrinolysis and inflammation. The aim of this study was to investigate the diagnostic and prognostic value of systemic and pulmonary levels of suPAR in burn patients with inhalation trauma who need mechanical ventilation.

Methods

suPAR was measured in plasma and nondirected lung-lavage fluid of mechanically ventilated burn patients with inhalation trauma. The samples were obtained on the day of inhalation trauma and on alternate days thereafter until patients were completely weaned from the mechanical ventilator. Mechanically ventilated patients without burns and without pulmonary disease served as controls.

Results

Systemic levels of suPAR in burn patients with inhalation trauma were not different from those in control patients. On admission and follow up, pulmonary levels of suPAR in patients with inhalation trauma were significantly higher compared with controls. Pulmonary levels of suPAR highly correlated with pulmonary levels of interleukin 6, a marker of inflammation, and thrombin-antithrombin complexes, markers of coagulation, but not plasminogen activator activity, a marker of fibrinolysis. Systemic levels of suPAR were predictive of the duration of mechanical ventilation and length of intensive care unit (ICU) stay. Duration of mechanical ventilation and length of ICU stay were significantly longer in burn-injury patients with systemic suPAR levels > 9.5 ng/ml.

Conclusions

Pulmonary levels of suPAR are elevated in burn patients with inhalation trauma, and they correlate with pulmonary inflammation and coagulation. Although pulmonary levels of suPAR may have diagnostic value in burn-injury patients, systemic levels of suPAR have prognostic value.

The diagnostic and prognostic significance of soluble urokinase plasminogen activator receptor in systemic inflammatory response syndrome

OBJECTIVES

This study was intended to investigate the value of suPAR, C-reactive protein (CRP) and procalcitonin (PCT) in the determination and prognosis of systemic inflammatory response syndrome (SIRS) patients.

METHODS

The study was performed among patients with at least two SIRS criteria. PCT, CRP and suPAR were analyzed from the blood specimens taken.

RESULTS

Eighty-five patients were enrolled in the SIRS group (44 bacteremia, 20 urinary tract infection, 12 pneumonia and 9 non-infection), and 53 individuals in the control group. A significant correlation was determined between suPAR, PCT and CRP values in both groups (P<0.0001). A suPAR cutoff value of 2.8ng/mL was associated with an NPV of 87% and PPV of 91%, with 92% sensitivity and 85% specificity. A relatively high suPAR level that might predict fatality was also determined in fatal cases (P=0.001).

CONCLUSION

suPAR possesses high sensitivity and specificity levels in terms of differential diagnosis, and high suPAR levels can predict fatality.