A diagnostic test: combined detection of heparin-binding protein, procalcitonin, and C-reactive protein to improve the diagnostic accuracy of bacterial respiratory tract infections.

Background: Respiratory tract infection (RTI) is one of the most common diseases worldwide, and its incidence is rising year by year due to environmental pollution. Sputum culture remains the gold standard for RTI diagnosis, but its performance is limited by difficulties related to the sampling and testing of the sputum specimens. Heparin-binding protein (HBP), procalcitonin (PCT), and C-reaction protein (CRP) are Inflammatory markers. They have the advantage of being fast, accurate and reproducible, but limited by their sensitivity and specificity. We explored the clinical value of the combined detection of them in the diagnosis of bacterial RTIs. Methods: Patients who fulfilled the inclusion criteria were selected as the case group, healthy age- and sex-matched subjects were enrolled as a control group. The subjects' HBP, PCT, and CRP levels were detected. The case group was further divided into two groups according to the bacterial culture results, and the differences in the markers were statistically analyzed. The receiver operating characteristic (ROC) curves were drawn, and the areas under the ROC curve (AUCs) were calculated to analyze the diagnostic values of each marker and their combination in parallel for bacterial RTIs. Results: The plasma HBP, PCT, and CRP levels of patients in the bacterial and non-bacterial infection groups were significantly higher than those of patients in the healthy control group, and were positively correlated to the severity of the disease. for HBP with an AUC of 0.785 [95% confidence interval (CI): 0.686-0.884], a sensitivity of 0.821, a specificity of 0.771; PCT with an AUC of 0.767 (95% CI: 0.664-0.870), a sensitivity of 0.773, a specificity of 0.791, and CRP with an AUC of 0.748 (95% CI: 0.642-0.854), a sensitivity of 0.839, a specificity of 0.696 in the bacterial and non-bacterial infection groups. The combined detection of HBP + CRP had the optimal diagnostic performance, with an AUC of 0.797 (95% CI: 0.698-0.895; P<0.001), a sensitivity of 0.809, a specificity of 0.800. Conclusions: The combined detection of HBP and CRP is valuable for diagnosing bacterial RTIs and may guide the development of reasonable treatment protocols in clinical settings.