INTRODUCTION
Acute bronchiolitis (AB) is a lower respiratory tract infection that affects approximately 20% of all children, resulting in hospitalization for 2-3% of them under 12 months of age. Mortality from AB occurs predominantly in developing countries. In developed countries it is associated with various complex chronic conditions and sociodemographic risk factors.
AB classically presents with increased respiratory effort and wheezing, often accompanied by systemic manifestations such as fever or apnea, a common symptom in neonates. a common disease is of 14-21 days with peak symptoms at days 3-5. guidelines recommend avoiding laboratory or radiographic evaluations. Nonetheless, these are often performed in various clinical settings.
The most common viral pathogen associated with bronchiolitis is Respiratory Syncytial Virus (RSV), which accounts for 50-80% of cases, and is associated with more severe disease. Co-infections with other viruses are seen in up to 30% of cases. Secondary bacterial infections, such as AOM, Pneumonia, and UTI (37-74%, up to 32%, 1-7% respectively) (7,9) have been reported in hospitalized patients. (7,9–11). Respiratory failure requiring invasive or non-invasive ventilation occurs in 3-19% of hospitalized children, usually in PICU settings.
C-reactive protein (CRP), an acute phase reactant which is synthesized in the liver, acts as a mediator between the innate and acquired immune systems. Peaking 48-72 hours after the onset of an inflammatory response, it is a common clinical tool for diagnosis and monitoring of inflammatory responses. Only a few studies have examined the relevance of CRP in RSV bronchiolitis. These studies identified a correlation between higher CRP levels and an increased risk of severe disease particularly in cases of radiologically confirmed pneumonia, or the diagnosis of sepsis in PICU settings.
In this study, our objective is to investigate the correlation between CRP levels on admission and the severity of RSV bronchiolitis, as well as any related complications in hospitalized children. Additionally, we aim to propose specific cutoff values for CRP levels that are indicative of different severity outcomes, such as the incidence of secondary infections, prolonged length of stay in the hospital (LOS), and the need for PICU admission.