Introduction
Acute bronchiolitis is a lower airway disease frequently seen in children under the age of two years and generally characterized by inflammation of the small airways caused by viral agents. Onset occurs with upper airway infection findings such as cough and nasal discharge, followed by wheeze, prolonged expiration, rapid breathing, and retractions in the chest.1,2 Rapid respiration, retractions caused by the functioning of the accessory respiratory muscles, and low oxygen saturation are evaluated as severe disease findings.1
Acute bronchiolitis is more common in boys, in children who are not breastfed, in those exposed to cigarette smoke, and in the children of families of low socioeconomic status.2 The course of the disease is severe in some patients, and may require hospitalization and intensive care. Children with histories of premature birth, babies younger than three months, and patients with cardiovascular, neurological, or pulmonary diseases and immune deficiency are at risk of developing acute bronchiolitis.1,2 Living under crowded conditions and the presence of siblings have also been described as risk factors for development of severe bronchiolitis.3,4 Since maternal smoking during pregnancy increases hospitalization rates and results in a severe course of disease in patients with bronchiolitis, respiratory support with mechanical ventilation may be required.5,6 A history of airway disease in the perinatal and neonatal period has been reported to increase the risk of bronchiolitis and hospitalization.4 It has also been suggested that genetic factors may affect a severe disease course.7
Identifying factors increasing the risk of acute bronchiolitis development in patients with no chronic disease is important in terms of standardizing the frequency of follow-ups and hospitalization indications in bronchiolitis patients, and in terms of deciding to intervene early in case of at-risk patients. The purpose of the present study was to determine predictive individual, familial, and environmental risk factors for development of severe bronchiolitis in healthy-appearing acute bronchiolitis patients with no previous history of chronic disease.