Overweight Infants at Risk for Severe Disease in Bronchiolitis

Background: Despite the well-known association between respiratory diseases and obesity in older children and adults, there is a paucity of literature in infants. While some studies have demonstrated negative effects of increased weight in infants on respiratory function, the effect in bronchiolitis remains unknown. Bronchiolitis is the leading cause of hospitalization in infants and many risk factors for severe disease have been identified including prematurity and cardiopulmonary disease. Our aim was to evaluate the effect of being overweight on the outcomes of infants hospitalized with bronchiolitis.

Methods: This retrospective cohort study analyzed hospitalized infants (ages one to twelve months) at a tertiary children’s hospital with a diagnosis of bronchiolitis from September 2019 to April 2020. Exclusion criteria included prematurity ( <37 weeks), congenital heart disease, chronic lung disease, immunosuppression, trisomy 21, neuromuscular disorders, and concurrent pneumonia. Weight-for-length Z-score was calculated and categorized per the World Health Organization’s parameters for growth problems as overweight (Z-score > 2), underweight (Z-score < -2), and between (-2 ≤ Z-score ≤ 2). Primary outcomes collected were length of stay (LOS), highest respiratory support, intensive care unit (ICU) stay, and locally validated bronchiolitis severity score. Secondary outcomes included intravenous fluid or nasogastric use, nasal and nasopharyngeal suctioning, positive expiratory pressure (PEP) therapy, albuterol administration, and chest radiographs.

Results: During the study period, there were 737 infants hospitalized with bronchiolitis. After exclusion criteria were applied, 385 infants were categorized as overweight (n=24), underweight (n=26), or in between (n=335). There was no difference in LOS by days [median (interquartile (IQR)) days; overweight: 1.96 (1.37-3.07), underweight: 2.36 (1.15-4.36), between: 2.80 (1.84-3.9), p=0.072]. However, there were significant differences in need for high flow nasal cannula (overweight: 75%, underweight: 42%, between: 48%, p=0.029), admission to ICU (overweight: 54%, underweight: 35%, between: 21% p<0.001), and median bronchiolitis score [overweight: 8 (5-10), underweight: 4 (3-7), between: 4 (3-7), p=0.013]. There was also a significant difference in frequency of PEP therapy and nasopharyngeal suctioning, with overweight experiencing the highest rates [median (IQR); PEP: overweight: 5 (0-8.5), underweight: 3 (0-3), between: 0 (0-6), p=0.050; and suction: overweight: 11.5 (7.5-16), underweight: 6 (3-18), between: 7 (3-13), p=0.043].

Conclusion: Knowing risk factors for disease severity allows clinicians to predict outcomes in hospitalized infants with bronchiolitis. While overweight infants had similar LOS to other infants, they required higher levels of support including more frequent need of HFNC and admission to ICU. They also had higher bronchiolitis scores and experienced more frequent PEP therapy and nasopharyngeal suctioning. This novel study suggests overweight is a risk factor for severe disease in infants hospitalized for bronchiolitis.