OBJECTIVE: To investigate the interaction between α-amylase (α-AMS) and inflammatory response in patients with ventilator-associated pneumonia (VAP) and their predictive value for prognosis. METHODS: A prospective cohort study was conducted. Patients with mechanical ventilation who were treated in the intensive care unit (ICU) of the Second Hospital of Hebei Medical University from June 2020 to June 2023 were enrolled, and the patients were divided into VAP group and non-VAP group according to whether VAP occurred. VAP patients were stratified into mild [acute physiology and chronic health evaluation II (APACHE II) < 10 scores], moderate (APACHE II were 10-20 scores), and severe (APACHE II > 20 scores) groups based on the APACHE II. All patients were followed up for 28 days. In addition, healthy subjects who underwent health examination in our hospital at the same time were selected as the healthy control group. Baseline data including gender, age, mechanical ventilation mode, mechanical ventilation time, underlying diseases, drug use, and laboratory test indicators were collected. The serum levels of α-AMS, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), C-reactive protein (CRP) and other inflammatory factors were analyzed and compared. Pearson correlation analysis was performed to analyze the correlation between serum α-AMS and inflammatory factors. Logistic regression was used to analyze the influencing factors of poor prognosis in patients with VAP. The receiver operator characteristic curve (ROC curve) was plotted to evaluate the predictive value of α-AMS on the poor prognosis of patients with VAP. RESULTS: A total of 100 mechanically ventilated patients were enrolled, including 60 cases in the VAP group and 40 cases in the non-VAP group. Among the patients with VAP, there were 24 cases in the mild group, 20 cases in the moderate group, and 16 cases in the severe group. A total of 44 patients survived at 28 days, while 16 died. Additionally, 100 healthy individuals were included as the healthy control group. Serum levels of α-AMS, IL-6, TNF-α and CRP in the VAP group were significantly higher than those in the non-VAP group and the healthy control group, while the levels of α-AMS, IL-6, TNF-α and CRP in the non-VAP group were significantly higher than those in the healthy control group. There were statistically significant differences in serum α-AMS, IL-6, TNF-α, CRP levels and APACHE II scores among VAP patients with different disease severities, and the levels of the above indicators in the severe group were significantly higher than those in the moderate group and mild group, and the levels of the above indicators in the moderate VAP group were significantly higher than those in the mild group. Pearson correlation analysis showed that serum α-AMS was positively correlated with IL-6, TNF-α, CRP, and APACHE II scores (r values were 0.404, 0.392 and 0.493, 0.493, all P < 0.01). Univariate analysis showed that age, mechanical ventilation, diabetes mellitus, ventilation time, ventilation position, prophylactic use of antimicrobial drugs, and serum α-AMS, IL-6, TNF-α, CRP, and APACHE II scores were correlated with the prognosis of VAP patients (all P < 0.05). Multivariate Logistic regression analysis identified age [odds ratio (OR) = 1.340, 95% confidence interval (95%CI) was 1.119-1.605], tracheostomy (OR = 3.050, 95%CI was 1.016-9.157), diabetes mellitus (OR = 1.379, 95%CI was 1.102-1.724), and ventilation time ≥ 7 days (OR = 2.557, 95%CI was 1.163-5.623) and serum α-AMS (OR = 1.428, 95%CI was 1.098-1.856), IL-6 (OR = 1.543, 95%CI was 1.005-2.371), TNF-α (OR = 2.228, 95%CI was 1.107-4.485), CRP (OR = 1.252, 95%CI was 1.131-1.387), APACHE II scores (OR = 1.422, 95%CI was 1.033-1.957) were independent influencing factors for the 28-day prognosis of patients with VAP (all P < 0.05). ROC curve analysis demonstrated that serum α-AMS, IL-6, TNF-α and CRP exhibited significant predictive performance on the prognosis of patients with VAP. The best cut-off value for α-AMS had a sensitivity of 81.3%, specificity of 75.0%, and an area under the ROC curve (AUC) of 0.791, which was significantly higher than those of inflammatory markers IL-6, TNF-α, and CRP (P < 0.05). The combined parameter diagnostic performance was significantly better than those of individual parameters (P < 0.05), with the highest diagnostic performance when combined, corresponding to an AUC of 0.868 (95%CI was 0.798-0.938), sensitivity of 87.5%, and specificity of 79.5%. CONCLUSIONS VAP in mechanically ventilated patients can lead to an increase in the levels of peripheral blood α-AMS and inflammatory factors, and there is an interaction between α-AMS and inflammatory markers in severe VAP patients. These markers are closely related to the severity of the disease and prognosis and have significant implications for predicting patient outcomes.
Humans ; Pneumonia, Ventilator-Associated/diagnosis* ; Prognosis ; Prospective Studies ; Respiration, Artificial ; alpha-Amylases/blood* ; Interleukin-6/blood* ; Male ; Female ; C-Reactive Protein/metabolism* ; APACHE ; Inflammation ; Middle Aged ; Intensive Care Units ; Tumor Necrosis Factor-alpha/blood* ; Aged