Background

Lung ultrasound (LUS) and procalcitonin (PCT) are independently used to improve accuracy when diagnosing lung infections. The aim of the study was to evaluate the accuracy of a new algorithm combining LUS and PCT for the diagnosis of bacterial pneumonia.

Methods

Randomized, blinded, comparative effectiveness clinical trial. Children <18 years old with suspected pneumonia admitted to Pediatric Intensive Care Unit were included, and randomized into experimental group (EG) or control group (CG) if LUS or chest X-ray (CXR) were done as the first pulmonary image, respectively. PCT was determined. In patients with bacterial pneumonia, sensitivity, specificity, and predictive values of LUS, CXR, and of both combined with procalcitonin were analyzed and compared. Concordance between the final diagnosis and the diagnosis concluded through the imaging test was assessed.

Results

194 children, with a median age of 134 (IQR 39-554) days, were enrolled, 96 randomized into the EG and 98 into the CG. Bacterial pneumonia was diagnosed in 97 patients. Sensitivity and specificity for bacterial pneumonia diagnosis were 78%(95%CI 70-85) and 98%(95%CI 93-99) for LUS, 85%(95%CI 78-90) and 53%(95%CI 43-62) for CXR, 90%(95%CI 83-94) and 85%(95%CI 76-91) when combining LUS&PCT, and 95%(95%CI 90-98) and 41%(95%CI 31-52) when combining CXR&PCT. The positive predictive value for LUS&PCT was 88%(95%CI 79-93%) vs. 68%(95%CI 60-75) for CXR&PCT. The concordance between the final diagnosis and LUS had a kappa value of 0.69(95%CI 0.62-0.75) vs.0.34(95%CI 0.21-0.45) for CXR, (p<0.001).

Conclusions

The combination of LUS and procalcitonin presented a better accuracy for bacterial pneumonia diagnosis than combining CXR and procalcitonin. Therefore, its implementation could be a reliable tool for pneumonia diagnosis in critically ill children.

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