Is Lung Ultrasound Useful for Diagnosing Pneumonia in Children?: A Meta-Analysis and Systematic Review

Background Childhood mortality due to pneumonia is high. Chest radiography is the primary imaging modality used for the evaluation of pneumonia in children. Lung ultrasonography (LUS) is a newer, alternative diagnostic method that has been gaining popularity in recent years. We conducted a meta-analysis to summarize the diagnostic usefulness of LUS for childhood pneumonia. Methods All studies included in this meta-analysis were retrieved from PubMed, Elsevier's Science Direct, and Springer, and by manual searches including the use of reference lists, through March 31, 2017. Two researchers independently screened the literature, extracted the data, and evaluated risks of bias in accordance with the inclusion and exclusion criteria. For the meta-analysis, we calculated the pooled sensitivity and specificity, pooled positive likelihood ratio, negative likelihood ratio, and the diagnostic odds ratio. Summary receiver operating characteristic curve was used to assess the overall performance of LUS. Results Our search identified 1038 articles, and we selected 51 of these for detailed review. Eight studies containing 1013 patients met all the inclusion criteria and were included in the final meta-analysis. The pooled sensitivity and specificity for the diagnosis of pneumonia using LUS were 93.0% (95% confidence interval, 88.0%-96.0%) and 96.0% (95% confidence interval, 92.0%-98.0%), respectively. The pooled positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 25.8 (11.0, 60.4), 0.07 (0.05, 0.12), and 344 (104, 1140), respectively. In addition, the summary receiver operating characteristic area under the curve was calculated to be 0.98 (0.97, 0.99). A Fagan plot analysis demonstrated that when pretest probabilities were 25%, 50%, and 75%, the positive posttest probabilities were 90%, 96%, and 99%, respectively, and the negative posttest probabilities were 2%, 7%, and 18%, respectively. Four clinical signs were most frequently observed using LUS in the screening of children with pneumonia: pulmonary consolidation, positive air bronchogram, abnormal pleural line, and pleural effusion. Conclusions Current evidence supports LUS as a useful imaging alternative for the diagnosis of childhood pneumonia. That it is easily carried out, readily available, relatively inexpensive, and free from the hazards of radiation make it an attractive alternative to chest radiography and physical examination for the diagnosis and the follow-up of pneumonia in children.