Diagnostic value of serum amyloid A, procalcitonin and hypersensitive C-reactive protein for pulmonary tuberculosis complicated by pneumonia

Abstract

To assess the value of serum amyloid A (SAA), procalcitonin (PCT) and high-sensitivity C-reactive protein (hs-CRP) in the diagnosis of pulmonary tuberculosis (PTB) complicated by pneumonia. We collected serum samples from patients with pneumonia, patients with PTB, patients with PTB complicated by pneumonia and patients with PTB complicated by sepsis hospitalized in our hospital between April, 2019 and April, 2020. Serum levels of SAA, PCT and hs-CRP were tested, and receiver- operating characteristic (ROC) curves were used to evaluate their efficacy for predicting PTB with concurrent pneumonia and the possibility of differentiating PTB cases with pneumonia from those with sepsis using these 3 parameters. We also tested serum levels of SAA, PCT and hs-CRP in patients with PTB and those with PTB complicated by pneumonia admitted from May to July in 2020 to verify the accuracy of these 3 parameters combined for predicting the complication of PTB by pneumonia. Compared with the patients with PTB, the patients with pneumonia had significantly higher SAA and hs-CRP levels; serum SAA, PCT and hs-CRP levels were all significantly elevated in patients with PTB complicated by pneumonia (all P < 0.05). The levels of hs-CRP, white blood cell, D-dimer, FIB, APTT and neutrophil ratio were positively correlated with serum SAA level (all P < 0.05). The areas under the ROC curve (AUC) for serum SAA, PCT, and hs-CRP were 0.762, 0.781, and 0.800, respectively, and their combined AUC was 0.849 (all P < 0.001). For predicting PTB complicated by pneumonia, SAA combined with PCT had the same sensitivity (53.85%) and specificity (90.48%) as SAA, PCT and hs-CRP all combined. Serum SAA and PCT levels were similar between PTB patients with pneumonia and those with sepsis. Combined detection of serum SAA and PCT levels can be helpful in the diagnosis of PTB complicated by pneumonia, but neither of them is capable of differentiating the complication of pneumonia from sepsis possibly due to influence by abnormal blood coagulation.