Use of Saliva Sample to Detect C-Reactive Protein in Children with Pneumonia.

Background Serum C-reactive protein (CRP) is a sensitive biomarker for inflammation and is broadly used to clinically diagnose infectious diseases, including pneumonia. However, blood sampling is fraught with technical difficulties in children. The salivary analysis may be a potential diagnostic tool, as it is noninvasive, patient-friendly, and easy to perform in children. This study aimed to evaluate the use of salivary CRP as a biomarker for children with pneumonia. Methods A prospective study was conducted in patients aged 2 to 17 years, admitted to the hospital with pneumonia. Saliva and serum samples for CRP and chemokine determination were collected at the initial admission and during a follow-up from pediatric patients with pneumonia. Salivary samples were also collected from healthy subjects used as controls. Results A total of 60 healthy children and 106 pediatric patients with pneumonia were enrolled in this study. The salivary CRP level was much higher in pediatric patients with pneumonia than in healthy children (48.77 +/- 5.52 ng/mL vs 14.78 +/- 3.92 ng/mL;P < .001). Salivary CRP level was highly correlated with serum CRP level in pediatric patients with pneumonia (r = .679;P < .001). Salivary CRP level (>= 40.307 ng/mL) can be used to predict high serum CRP levels (>= 80 mg/L) with an area under the curve of 0.810 (95% confidence interval, 0.740-0.881). As pneumonia improved, both salivary and serum CRP levels decreased during follow-up. Conclusions Salivary CRP could be an alternative biomarker for serum CRP in pediatric patients with pneumonia. This is especially beneficial for pediatric patients, as saliva collection is simple, noninvasive, and patient-friendly.