Materials and Methods
Four hundred forty children aged 1-24 months hospitalized with diagnoses of acute bronchiolitis between February 2018 and February 2019 were included in this prospective study. The study was designed in compliance with the principles of the Declaration of Helsinki, and approval was granted by the Clinical Research Ethical Committee (No. 2018/1-6 dated 23.01.2018). Informed consent forms were obtained from individuals legally responsible for the care of the patients included in the study.
Patients younger than one or older than 24 months, or with histories of congenital heart disease, neuromuscular disease, immunodeficiency, chronic lung disease (such as cystic fibrosis or bronchopulmonary dysplasia), metabolic disease, or sibling death were excluded from the study.
Marked retractions resulting from the functioning of the accessory respiratory muscles, an increased respiration rate, and oxygen saturation of 90% or less were regarded as severe bronchiolitis.1 Weight-for-age z-score values of +2.00 or above were regarded as obesity, values between -1.00 and -1.99 as mild malnutrition, scores between -2.00 and -2.99 as moderate malnutrition, and values of -3.00 or below as severe malnutrition.
The age, sex, weight, and weight-for-age z-score of patients hospitalized to the infant ward were recorded. Weight-for-age z-scores were calculated using the World Health Organizations (WHO) Anthro software. The presentation symptom, time of onset, and time elapsed between onset and worsening of symptoms were subsequently investigated. Data concerning type of delivery and gestational week, type of feeding (mother’s milk only, mother’s milk plus formula, or formula only), presence of atopy/food allergy, previous history of bronchiolitis, history of admission to the neonatal intensive care unit (NICU), and presence of gastroesophageal reflux disease (GERD) were also recorded. Parental history of asthma, history of maternal smoking during pregnancy, history of smoking in the home, parental education levels, number of siblings, and number of individuals in the household were also noted. Characteristics of the place of residence (rural area or urban, type of heating, and type of accommodation) were investigated in the environmental history. The patient’s physical examination findings, type of feeding during the disease, oxygen requirements, bronchiolitis clinical status, methods providing oxygen support (mask, high-flow nasal cannula (HFNC), or intubation), and data concerning treatment were recorded. Laboratory parameter findings such as white blood cell (WBC) count, hemoglobin (Hb), platelet count, absolute neutrophil count (ANC), lymphocyte count, serum C-reactive protein (CRP), and blood gas values (pH, partial carbon dioxide pressure (pCO2), partial oxygen pressure (pO2) and bicarbonate (HCO3)) were also recorded.
Statistical Analyses
Data were analyzed on Statistical Package for Social Sciences Statistical Software, version 23.0 (SPSS Inc., Chicago, IL, USA). Descriptive statistics were produced. Data were expressed as number (percentage) or mean±standard deviation (minimum-maximum). Categorical data were compared using the chi-square and Fisher’s exact tests. The Kolmogorov-Smirnov test was applied to determine whether continuous data were normally distributed. Normally distributed data were expressed as mean±standard deviation (minimum-maximum) and were compared using the independent two sample t test. p values <0.05 were regarded as statistically significant.
Single variable logistic regression analysis was applied to identify independent predictors of severe bronchiolitis development, and the parameters determined were then subjected to multivariate logistic regression analysis (backward LR model).