To investigate the value of serum soluble myeloid cell triggered receptor-1 (sTREM-1) in the early diagnosis of severe pneumonia.

Total of 60 patients with pneumonia who were treated in The Second Hospital of Jilin University from June 2021 to December 2021 were incorporated in study group, including 40 severe cases (severe pneumonia group) and 20 mild cases (common pneumonia group). Another 15 physical examiner during the same period were selected as control group. All patients in study group were evaluated by the pneumonia severity index (PSI) score within 24 hours after admission. The immunoscattering turbidimetry, electrochemical luminescence and enzyme-linked immunosorbent assay (ELISA) were used to detect the levels of serum procalcitonin (PCT), hypersensitive C-reactive protein (hs-CRP) and sTREM-1, respectively. The levels of serum sTREM-1 in severe pneumonia group, common pneumonia group and control group within admission 24 hours were compared, and the levels of PCT, hs-CRP and PSI score in severe and common pneumonia group within admission 24 hours were compared, respectively. The correlation between serum sTREM-1 and hs-CRP and PSI score were analyzed by Pearson correlation analysis; the correlation between serum PCT and PSI score were analyzed by Spearson correlation analysis. The value of serum sTREM-1, PCT and hs-CRP in the early diagnosis of severe pneumonia were compared by the area under receiver operating characteristic curve (ROC) by MedCalc software.

The levels of serum sTREM-1 in severe pneumonia group, common pneumonia group and healthy control group (4 864.81 ± 1 314.53 pg/ml, 1 144.58 ± 571.01 pg/ml, 509.11 ± 43.70 pg/ml) were significantly different (F = 109.292, P < 0.001), and the levels of serum sTREM-1 of severe pneumonia group was significantly higher than those of common pneumonia group and control group (t = 10.981, P < 0.001; t = 9.264, P < 0.001). The levels of serum PCT, hs-CRP and PSI score in severe pneumonia group were significantly higher than those in common pneumonia group (Z =-3.360, P = 0.001; t = 2.047, P = 0.048; t = 4.878, P < 0.001). The AUCs of serum sTREM-1, PCT and hs-CRP for diagnosis of severe pneumonia were 1.00, 0.86 and 0.68, respectively (95%CI: 1.0-1.00, 0.73-0.98, 0.51-0.86). When 2 916.92 pg/ml, 0.31 ng/ml and 32.14 mg/L were selected as the Cut-off values, respectively, Youden index was highest; the corresponding sensitivity were 100%, 85% and 85%, while the specificity were 100%, 81% and 50%, respectively. The AUC of sTREM-1 for diagnosis of severe pneumonia was significantly different from those of hs-CRP and PCT (Z = 3.463, P < 0.001; Z = 2.220, P = 0.026). And there was no significant difference between hs-CRP and PCT (Z = 1.454, P = 0.146). The PSI score was positively correlated with the serum sTREM-1 (r = 0.641, P < 0.001) and PCT (r = 0.540, P = 0.001). However, there was no correlation between PSI score and serum hs-CRP (r = 0.269, P = 0.124).

The level of serum sTREM-1 increased in pneumonia, especially in severe cases, which is positively correlated with PSI score. The detection of serum sTREM-1 is valuable for the early diagnosis of severe pneumonia, and its specificity and sensitivity are higher than those of PCT and hs-CRP. It is expected to become a new biomarker for early diagnosis of severe pneumonia.