Systemic cytokines/chemokines associated to radiographic abnormalities in pneumonia in children

Abstract

Community-acquired pneumonia (CAP) diagnosis remains a challenge in paediatrics. Chest radiography is considered gold standard for definition of pneumonia, however no previous study assessed the relationship between immune response and radiographic-confirmed-pneumonia. We assessed association between cytokines/chemokines levels and radiographic abnormalities in children with CAP.Children < 5-years-old hospitalized with CAP were investigated in a prospective study at the Federal University of Bahia Hospital, Brazil. On admission, clinical data and biological samples were collected to investigate 20 aetiological agents and determine serum cytokines/chemokines levels; chest radiographs were performed.Among 158 patients, radiographic diagnosis of pneumonia was confirmed in 126(79.7%) and 17(10.8%) had pleural effusion. Viral, bacterial and pneumococcal infection were detected in 80(50.6%), 78(49.4%) and 37(23.4%) cases. By comparing the median concentrations of serum cytokines/chemokines between children with or without pleural effusion, interleukin(IL)-6 was higher (26.6[18.6–103.7] vs 3.0[0.0–19.8]; p < 0.001) among those with pleural effusion; and between children with or without radiographic-confirmed-pneumonia, IL-6 was higher in the first subgroup (4.5[0.0–23.4] vs 0.0[0.0–3.6]; p = 0.02) after having excluded cases with pleural effusion. Stratified analyses according to aetiology showed IL-6 increase in the radiographic-confirmed-pneumonia subgroup inside the pneumococcal infection (28.2[5.9–64.1] vs 0.0[0.0–0.0]; p = 0.03) subgroup. By multivariable analysis, with IL-6 as dependent variable, pneumococcal infection and pleural effusion showed independent association with IL-6 elevation [respective OR: 5.071 (95%CI = 2.226–11.548; p < 0.001) and 13.604 (95%CI = 3.463–53.449; p = 0.0001)]. Considering the cases without pleural effusion, the area under the curve of IL-6 to predict pneumococcal infection was 0.76 (95%CI = 0.66–0.86; p < 0.001).IL-6 increase is a potential biomarker of pneumococcal infection among children with CAP without pleural effusion upon admission.