Clinical study of cystatin C in assessing the severity of community acquired pneumonia

Abstract

Objective To explore the clinical value of cystatin C in predicting the severity of community-acquired pneumonia(CAP). Methods From January 2016 to August 2016, the clinical data of 122 patients with CAP in Shengjing Hospital of China Medical University were retrospectively analyzed.The patients were divided into low-risk group(74 cases) and middle-high risk group(48 cases) according to pneumonia severity index (PSI). The cystatin C, procalcitonin, C-reactive protein(CRP), white blood cell (WBC) count, neutrophil percentage(NE%), D-dimer and fibrinogen(FIB) levels in hospitalized patients were detected.The relationship between cystatin C and the above related indicators and the PSI was evaluated.Draw ROC curve with cystatin C and above indicators to predict severity of CAP. Results In the low-risk group, the levels of procalcitonin, CRP, WBC count, NE%, D-dimer, FIB were[0.08(0.04, 0.23)]ng/L, [42.35(12.52, 93.70)]mg/L, [7.85(6.23, 10.38)]×109/L, (66.87±13.49)%, [215.00(134.25, 410.25)]μg/L, [4.52(3.71, 5.14)]g/L, respectively, which in the middle and high risk group were [0.25(0.07, 0.54)]ng/L, [74.30(40.45, 122.75)]mg/L, [7.90(5.78, 10.63)]×109/L, (73.97±10.77)%, [417.50(239.75, 730.00)]μg/L, [4.57(3.87, 5.08)]g/L, respectively, the differences of NE%, procalcitonin, CRP, D-dimer between the two groups were statistically significant(t=3.064, U=3.024, 2.800, 3.771, all P 0.05). In the low-risk group, the level of cystatin C was[0.82(0.68, 0.91)]mmol/L, which in the middle-high risk group was[1.32(1.12, 1.54)]mmol/L, the difference between the two groups was statistically significant(U=7.978, P<0.001). When the level of cystatin C was 0.975 mmol/L, the sensitivity for the diagnosis of pneumonia severity was 95.8%, with a specificity of 85.1%. Conclusion Monitoring cystatin C levels can be used as an indicator of inflammatory response and can predict the severity of pneumonia. Key words: Cystatin c; Community-acquired infections; Procalcitonin; C-reactive protein; D-dimer; Fibrinogen; Leukocyte count; Neutrophils; Pneumonia; Severity of illness index