A novel biomarker of serum Histidine-Rich Glycoprotein (HRG) for diagnosing and predicting prognosis of ventilator-associated pneumonia (VAP): a pilot study.

OBJECTIVE: Histidine-Rich Glycoprotein (HRG) has been reported to be associated with idiopathic pulmonary fibrosis, cancer, and sepsis as a novel biomarker. However, there is limited evidence regarding its value in diagnosing or prognosis evaluating of ventilator-associated pneumonia (VAP).

PATIENTS AND METHODS: A total of 186 patients intubated in ICU and 65 healthy volunteers were enrolled in this study. Patients were divided into VAP group (n = 116), non-VAP group (n = 70) and control group (n = 65). The HRG, C reactive protein (CRP) and procalcitonin (PCT) levels were measured 72 hours after intubation, while blood sample was acquired from healthy controls for the test.

RESULTS: HRG of VAP group was significantly lower than non-VAP group and control group (p < 0.001), while CRP and PCT were significantly higher (p < 0.001). The ROC analysis showed that the AUC of HRG was 0.777 95% CI (0.708-0.847) with a cut-off value of 38.55 μg/mL, which was lower than CRP [AUC = 0.912, 95% CI (0.847-0.950)] and PCT [AUC = 0.818, 95% CI (0.759-0.876)]. No linear correlation was found between HRG and CRP, as well as PCT (p > 0.05). However, the survival analysis showed that patients with higher level of HRG had a significantly higher survival rate (p < 0.001). The multivariate Cox regression analysis also demonstrated that the higher level of HRG was associated with better survival [HR 0.290, 95% CI (0.131-0.641), p = 0.002].

CONCLUSIONS: Serum HRG decreases when the patient develops VAP, which might be used as a biomarker for the diagnosis of VAP, with relatively less accuracy than PCT and CRP. However, HRG is valuable in predicting the clinical outcomes of mechanical ventilation patients.