C-reactive protein and radiographic findings of lower respiratory tract infection in infants.

Abstract

AIM: To evaluate the association between C-reactive protein (CRP) and radiological evidence of lower respiratory tract infection (LRTI) in infants. METHODS: All patients aged less than 4 years who presented with suspected lower respiratory tract infection, who received a peri-presentation chest radiograph and CRP blood measurement over an 18-mo period were included in the study. Age, gender, source of referral, CRP, white cell count, neutrophil count along with the patients’ symptoms and radiologist’s report were recorded. RESULTS: Three hundred and eleven patients met the inclusion criteria. Abnormal chest radiographs were more common in patients with elevated CRP levels (P < 0.01). Radiologic signs of LRTI were identified in 73.7% of chest radiographs when a patient had a CRP level between 50-99 mg/L. CRP levels were a better predictor of positive chest radiograph findings for those aged greater than I year compared to those 1 year or less. CONCLUSION: CRP may be used in patients with suspected LRTI diagnosis to select those who are likely to have positive findings on chest radiograph, thus reducing unnecessary chest radiographs. Core tip: Abnormal chest radiograph findings are significantly more common in patients with elevated C-reactive protein (CRP) levels. Young children are most likely to have abnormal chest radiograph findings if they have all three of the following; a CRP level of 50-99 mg/L, respiratory symptoms and if they are aged greater than 1 year.