suPAR is associated with risk of future acute surgery and post-operative mortality in acutely admitted medical patients

Utilization of Prognostic Biomarker Soluble Urokinase Plasminogen Activator Receptor in the Emergency Department: A Tool for Safe and More Efficient Decision-making

Introduction:

Risk stratification in the emergency departments (EDs) is in critical need for new applications due to ED overcrowding and hospitalization of older people. We aimed to evaluate the expediency, efficiency and safety of a prognostic biomarker, soluble urokinase plasminogen activator receptor (suPAR), as a tool for the risk assessment of patients arriving at the ED.

Methods:

We performed a comparative cross-sectional study in 2 emergency departments (EDs), suPAR measurements being incorporated into routine blood sampling in the intervention ED. The primary outcome was the number of discharges from the ED. The importance of the outcomes was examined by appropriate multi- or bivariate analysis.

Results:

The absolute and relative number of discharges were similar between the intervention and control groups [121 (55.3%) vs 62 (55.9%)]. No significant differences between the groups were seen in the length of stays in the ED. Patients with low suPAR values were more likely discharged and patients with high suPAR values more likely admitted to hospital. Two admitted patients with low suPAR values could have been discharged safely.

Conclusion:

The utilization of suPAR did not increase the risk for neither positive nor negative outcomes. Low suPAR values could be potential in discharging more patients safely. Instead of unselected patient populations, the benefits of suPAR measurements in the ED could emerge in the assessment of a more precisely determined and selected group of patients.

Soluble urokinase plasminogen activator receptor (suPAR) in the emergency department: An update

BACKGROUND

The biomarker soluble urokinase plasminogen activator receptor (suPAR) is an indicator of inflammation which is increased in a variety of chronic and acute disease states. Its most promising application in the emergency setting is to aid in the prognostic stratification of patients by identifying those at high risk of deterioration. This is a narrative review of studies evaluating the use of suPAR.

METHODS

We conducted a Medline search for studies on the use of suPAR in patients acutely admitted to the emergency department.

RESULTS

25 original studies were included in the review. suPAR as a marker of inflammation has been used alone or combined to other inflammatory biomarkers in the assessment of patients suffering from various acute and chronic diseases in an emergency setting. As it is non-specific, it may increase in infectious disease, malignancy or acute coronary syndromes among other conditions, but quantitative suPAR levels correlate with disease severity. It may be useful for the identification of high risk patients regardless of underlying pathology.

CONCLUSION

As the ideal biomarker in the emergency setting has not been identified yet, suPAR may be a promising addition to the established biomarkers for the initial assessment of patients in this setting. Additional research is necessary to evaluate the usefulness of suPAR guided management algorithms.

suPAR cut-offs for stratification of low, medium, and high-risk acute medical patients in the emergency department

Background

Soluble urokinase plasminogen activator receptor (suPAR) levels have previously been associated with readmission and mortality in acute medical patients in the ED. However, no specific cut-offs for suPAR have been tested in this population.

Methods

Prospective observational study of consecutively included acute medical patients. Follow-up of mortality and readmission was carried out for 30- and 90 days stratified into baseline suPAR < 4, 4–6 and > 6 ng/ml. suPAR levels were measured using suPARnostic® Turbilatex assay on a Cobas c501 (Roche Diagnostics Ltd) analyser.

Results

A total of 1747 acute medical patients in the ED were included. Median age was 70 (IQR: 57–79) and 51.4% were men. Adjusted linear regression analysis showed that suPAR, independently of age, sex and C-reactive protein levels, predicted 30- and 90-day mortality (Odds ratio for doubling in suPAR 1.96 (95% confidence intervals: 1.42–2.70) Among patients with suPAR below 4 ng/ml (N = 804, 46.0%), 8 (1.0%) died within 90-day follow-up, resulting in a negative predictive value of 99.0% and a sensitivity of 94.6%. Altogether 514 (29.4%) patients had suPAR of 4–6 ng/ml, of whom 43 (8.4%) died during 90-day follow-up. Among patients with suPAR above 6 ng/ml (N = 429, 24.6%), 87 patients (20.3%) died within 90-day follow-up, resulting in a positive predictive value of 20.1% and a specificity of 78.7%.

Conclusions

suPAR cut-offs of below 4, between 4 and 6 and above 6 ng/ml can identify acute medical patients who have low, medium or high risk of 30- and 90-day mortality. The turbidimetric assay provides suPAR results within 30 min that may aid in the decision of discharge or admission of acute medical patients.

Elevated preoperative suPAR is a strong and independent risk marker for postoperative complications in patients undergoing major noncardiac surgery (SPARSE)

BACKGROUND

Patients undergoing major surgery are often at risk of developing postoperative complications. We investigated whether a preoperative marker of chronic inflammation, soluble urokinase plasminogen activator receptor, can aid in identifying patients at high risk for postoperative complications, morbidity, and mortality.

METHODS

In this prospective observational study (ClinicalTrials.gov identifier: NCT03851965), EDTA blood was collected from consecutive adult White patients scheduled for major noncardiac surgery with expected duration ≥2 hours under general anesthesia. Inclusion criteria were age ≥18 years and American Society of Anesthesiologists physical status I to IV. Plasma soluble urokinase plasminogen activator receptor levels were determined using the suPARnostic quick triage lateral flow assay. The primary endpoint was postoperative complications defined as presence of any complication and/or admission to intensive care unit and/or mortality within the first 90 postoperative days.

RESULTS

Preoperative soluble urokinase plasminogen activator receptor had an odds ratio of 1.50 (95% confidence interval: 1.24-1.82) for every ng/mL increase. When including age, sex, American Society of Anesthesiologists score, C-reactive protein, and grouped soluble urokinase plasminogen activator receptor in multivariate analysis, patients with soluble urokinase plasminogen activator receptor between 5.5 and 10 ng/mL had an odds ratio of 11.2 (confidence interval: 3.1-40.8) and patients with soluble urokinase plasminogen activator receptor >10 ng/mL had an odds ratio of 19.9 (95% confidence interval: 4.3-92.9) compared to patients with soluble urokinase plasminogen activator receptor ≤5.5 ng/mL, respectively. Receiver operating characteristic analysis of soluble urokinase plasminogen activator receptor showed an area under the curve of 0.82 (confidence interval: 0.72-0.91). Receiver operating characteristic analysis combining age, sex, C-reactive protein levels, and American Society of Anesthesiologists score and had an area under the curve of 0.71 (95% confidence interval: 0.61-0.82). Adding soluble urokinase plasminogen activator receptor to this model increased the area under the curve to 0.83 (95% confidence interval: 0.74-0.92) (P = .033).

CONCLUSION

Preoperative soluble urokinase plasminogen activator receptor provided strong and independent predictive value on postoperative complications in White patients undergoing major noncardiac surgery.

Preoperative Levels of the Soluble Urokinase-Type Plasminogen Activator Receptor as Predictor for New Episodes of Atrial Fibrillation After Vascular Surgery

INTRODUCTION

The soluble urokinase-type plasminogen activator receptor (suPAR) in uPAR soluble form is produced when the uPAR is cleaved from the cell membrane during the inflammatory process. Postoperative atrial fibrillation (AF) is the most common perioperative cardiac arrhythmia. It is speculated that elevated suPAR has a role in the development of AF. The aim of our study was to investigate the predictive role of preoperative suPAR in the occurrence of AF during the first 6 months after major vascular surgery.

METHODS

We included 119 male and 63 female patients with an average age of 67.19 ± 6.02 years, without permanent/persistent AF. Basic predictive model (BASIC) included traditional risk factors for AF: age, gender, body mass index-BMI, smoking status, presence of arterial hypertension, diabetes mellitus and dyslipidemia.

RESULTS

Over the 6-month period, 19 (10.4%) patients had one new episode of atrial fibrillation and 2 patients (1.1%) had 2 episodes of paroxysmal atrial fibrillation. Paroxysms of AF were significantly more frequent in patients who had a resection of an abdominal aneurysm than in patients with other types of major vascular surgery. BASIC had good discriminatory ability in the prediction of AF paroxysms during the first 6 months after surgery (AUC = 0.715, 95%CI 0.590-0.840). Adding suPAR to the basic model significantly improved the discriminative ability of the predictive model for AF episodes (ΔAUC = 0.238, p < 0.001). The predictive performance of the model BASIC+CRP+suPAR, measured using AUC, NRI and IDI statistics, was very similar to the model BASIC+suPAR.

CONCLUSION

AF is a common complication in surgical patients with high mortality and morbidity. suPAR could improve the ability of traditional risk factors to predict its occurrence up to 6 months after major vascular surgery.

Association of soluble urokinase plasminogen activator receptor levels with fibrotic and vascular manifestations in systemic sclerosis

OBJECTIVE

We assessed the association of suPAR (soluble urokinase plasminogen activator receptor) plasma levels with fibrotic and vascular manifestations in patients with systemic sclerosis (SSc).

METHODS

suPAR plasma levels were measured in 121 consecutive patients with SSc and correlated to pulmonary and vascular features of SSc, including interstitial lung disease as characterized by percentage of predicted CO diffusing capacity (DLco) and forced vital capacity (FVC), pulmonary fibrosis by computed tomography, and pulmonary arterial hypertension, telangiectasias, and digital ulcers.

RESULTS

Overall, 121 SSc patients (84% females; mean age, 57 ± 12 [range: 22-79] years) were enrolled; 35% had diffuse cutaneous SSc. suPAR plasma levels ranged from 1.3-10.2 [median: 2.9 (p25-p75: 2.3-3.9)] ng/mL. Log(suPAR) levels correlated with DLco (r = -0.41, p <0.0001) and FVC (r = -0.26, p = 0.004), also when adjusted for age, sex, and pulmonary hypertension. A suPAR cut-off level of >2.5 ng/mL showed a sensitivity of 91% for identifying patients with either DLco <50% or FVC < 60% of the predicted values. Similarly, 19 (90%) had a suPAR >2.5 ng/mL among those diagnosed with pulmonary fibrosis vs. 59 (60%) among those who did not (p = 0.008). suPAR values were not associated with vascular manifestations.

CONCLUSION

suPAR levels strongly correlated with pulmonary involvement in SSc. Future studies should test if suPAR estimation can be used for surveillance of severe pulmonary involvement in SSc.

Prognostic Value of Soluble Urokinase-Type Plasminogen Activator Receptor and High-Sensitivity C-Reactive Protein on Postoperative Mortality in Patients Undergoing Elective On-Pump Cardiac Surgery

OBJECTIVES

Elevated soluble urokinase-type plasminogen activator receptor (suPAR) and high-sensitivity C-reactive protein (hsCRP) have been associated with increased mortality in patients with cardiovascular disease. The aim of the present study was to explore the relationship between suPAR and hsCRP values and associated mortality after elective cardiac surgery. A secondary aim was to assess whether a combined risk model of European System for Cardiac Operative Risk Evaluation (EuroSCORE II), suPAR, and/or hsCRP would improve the prognostic accuracy compared with EuroSCORE II alone.

DESIGN

Retrospective observational study.

SETTING

Single-center, university hospital.

PARTICIPANTS

Adult patients admitted for elective on-pump cardiac surgery were included. Biobank blood samples were obtained from previous research projects at a tertiary heart center from 2012 to 2018.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 931 patients were included. Kaplan-Meier and Cox proportional hazard analyses were used to explore a potential association between preoperative suPAR and hsCRP values and all-cause mortality up to one year after surgery. Thirty-day mortality was predicted from suPAR, hsCRP, and EuroSCORE II by logistic regression and compared using area under the receiver operating characteristics curve and Brier scores. After adjustment for known confounders, a doubling of suPAR and hsCRP corresponded to a hazard ratio for all-cause mortality of 2.27 (95% confidence interval 1.65-3.11; p < 0.001) and 1.26 (95% confidence interval 1.07-1.49; p = 0.005), respectively. However, adding the biomarkers to EuroSCORE II did not improve prediction/discrimination with respect to 30-day mortality.

CONCLUSIONS

Elevated preoperative levels of suPAR and hsCRP were associated with all-cause mortality in elective cardiac surgery patients. However, inclusion of biomarkers did not improve the prognostic accuracy of EuroSCORE II.

Elevated suPAR Is an Independent Risk Marker for Incident Kidney Disease in Acute Medical Patients

Introduction

Identifying patients at high risk of developing kidney disease could lead to early clinical interventions that prevent or slow disease progression. Soluble urokinase plasminogen activator receptor (suPAR) is an inflammatory biomarker thought to be involved in the pathogenesis and development of kidney disease. We aimed to determine whether elevated plasma suPAR measured at hospital admission is associated with incident kidney disease in patients presenting to the emergency department.

Materials and Methods

This was a retrospective registry-based cohort study performed at the Emergency Department of Copenhagen University Hospital Amager and Hvidovre, Hvidovre, Denmark. Patients were included in the study from November 2013 to March 2017 and followed until June 2017. Patients were excluded if they were diagnosed with kidney disease or died prior to index discharge. Plasma suPAR was measured at hospital admission, and the main outcome was time to incident kidney disease, defined by ICD-10 diagnosis codes for both chronic and acute kidney conditions. Association between suPAR and time to incident kidney disease was assessed by Cox proportional hazard regression analysis.

Results

In total, 25,497 patients (median age 58.1 years; 52.5% female) were admitted to the emergency department and followed for development of kidney disease. In multivariable Cox regression analysis adjusting for age, sex, eGFR, CRP, cardiovascular disease, hypertension, and diabetes, each doubling in suPAR at hospital admission was associated with a hazard ratio of 1.57 (95% CI: 1.38–1.78, P < 0.001) for developing a chronic kidney condition and 2.51 (95% CI: 2.09–3.01, P < 0.001) for developing an acute kidney condition.

Discussion

In a large cohort of acutely hospitalized medical patients, elevated suPAR was independently associated with incident chronic and acute kidney conditions. This highlights the potential for using suPAR in risk classification models to identify high-risk patients who could benefit from early clinical interventions. The main limitation of this study is its reliance on accurate reporting of ICD-10 codes for kidney disease.

Early Discharge from the Emergency Department Based on Soluble Urokinase Plasminogen Activator Receptor (suPAR) Levels: A TRIAGE III Substudy

Objective

Using biomarkers for early and accurate identification of patients at low risk of serious illness may improve the flow in the emergency department (ED) by classifying these patients as nonurgent or even suitable for discharge. A potential biomarker for this purpose is soluble urokinase plasminogen activator receptor (suPAR). We hypothesized that availability of suPAR might lead to a higher proportion of early discharges.

Design

A substudy of the interventional TRIAGE III trial, comparing patients with a valid suPAR measurement at admission to those without. The primary endpoint was the proportion of patients discharged alive from the ED within 24 hours. Secondary outcomes were length of hospital stay, readmissions, and mortality within 30 days.

Setting

EDs at two university hospitals in the Capital Region of Denmark.

Participants

16,801 acutely admitted patients were included.

Measurements and Main Results

The suPAR level was available in 7,905 patients (suPAR group), but not in 8,896 (control group). The proportion of patients who were discharged within 24 hours of admittance was significantly higher in the suPAR group compared to the control group (50.2% (3,966 patients) vs. 48.6% (4,317 patients), P = 0.04). Furthermore, the mean length of hospital stay in the suPAR group was significantly shorter compared to that in the control group (4.3 days (SD 7.4) vs. 4.6 days (SD 9.4), P = 0.04). In contrast, the readmission rate within 30 days was significantly higher in the suPAR group (10.6% (839 patients) vs. 8.8% (785 patients), P < 0.001). Among patients discharged within 24 hours, there was no significant difference in the readmission rate or mortality within 30 days. Readmission occurred in 8.5% (336 patients) vs. 7.7% (331 patients) (P = 0.18) and mortality in 1.3% (52 patients) vs. 1.8% (77 patients) (P = 0.08) for the suPAR group and control group, respectively.

Conclusion

These post hoc analyses demonstrate that the availability of the prognostic biomarker suPAR was associated with a higher proportion of discharge within 24 hours and reduced length of stay, but more readmissions. In patients discharged within 24 hours, there was no difference in readmission or mortality.

Trial Registration of the Main Trial

This trial is registered with NCT02643459.