suPAR as a biomarker for pulmonary disease
The suPAR level is elevated in patients with infections and chronic diseases of the lungs and respiratory tract compared to healthy individuals. A high suPAR level is associated with:
- Bacteremia and sepsis1-4
- Asthma and poor disease control in asthma8
- COPD and in relation to an exacerbation9,10
- Incidence of future respiratory cancer11
- Poor prognosis1-7
In general, the suPAR level reflects the level of immune system activation regardless of etiology, and therefore the suPAR level is of no diagnostic value. However, in SIRS patients, it has been demonstrated that the suPAR level can discriminate patients with bacteremia from patients with no bacteremia. A combined model using suPAR, procalcitonin, and IL-6 showed an AUC of 0.804 to predict bacteremia in SIRS patients1.
The prognostic value of suPAR has been studied among patients with S. pneumoniae bacteremia2 and in patients with S. pneumoniae, S. aureus or E. coli bacteremia3.In both situations, significantly higher suPAR levels were found in non-survivors compared to survivors. In the bacteremia patients, a sensitivity of 83% and a specificity of 76% for mortality is found using a cut-off value of 11.0 ng/mL. A similar prognostic value was found in a study of patients with sepsis. Here, a cut-off value of 12 ng/mL is linked to >80% sensitivity and a negative predictive value of 94.5% for mortality4. In mechanically ventilated patients5 and children with pneumonia6,7, the suPAR level is elevated and associated with the seriousness of the disease and a poorer prognosis.
The suPAR level correlates with respiratory obstruction and can potentially help with the objective assessment of asthma8. In addition, the median suPAR level is significantly higher in asthmatics as compared to in healthy individuals (3.3 ng/mL vs 2.5 ng/mL)9.
“suPARnostic® … provide[s] quick and reliable results in less than one hour from patient sampling to results in the hands of the clinicians.”
Claus Lohman Brasen, Senior hospital physician, PhD, Dept. of Biochemistry and Immunology, Lillebaelt Hospital, Denmark
ViroGates Company announcement no. 15 – 2019
Similarly, in COPD patients, the suPAR level is significantly higher than in healthy individuals, and the median level is above the level in asthma patients (5.8 ng/mL vs 3.3 ng/mL)9.
Serum suPAR, CRP, and fibrinogen are significantly higher in COPD patients experiencing an exacerbation compared to healthy controls (4.8 ± 1.9 ng/mL vs 2.4 ± 0.9 ng/mL, respectively).
suPAR was superior to fibrinogen and CRP in identifying COPD patients experiencing an exacerbation. Only suPAR and fibrinogen were predictors of an exacerbation. Moreover, a negative correlation between suPAR and lung function, measured by FEV1, was found10.
In the general population, suPAR is associated with the incidence of respiratory cancer, even after adjustment for traditional risk factors like CRP and leucocytes11.
In a study including 2.838 acutely admitted medical patients with COPD as primary (AECOPD) or secondary diagnose, median suPAR levels were significantly higher among patients who died within 30-days compared with those who survived (5.7 ng/mL (IQR 3.8-8.1) vs 3.6 ng/mL (2.7-5.1), P < 0.0001)12.