708 - Association between Neonatal Lung Mechanics and Hospitalization with Viral Lower Respiratory Tract Infections in Infancy

Publication Number: 4692.708

Courtney A. Swain, University of Alabama School of Medicine, Birmingham, AL, United States; Kimberly Armstead, University of Alabama School of Medicine, Birmingham, AL, United States; Waldemar Carlo, University of Alabama, Birmingham, AL, United States; Namasivayam Ambalavanan, University of Alabama School of Medicine, Birmingham, AL, United States; Colm P. Travers, University of Alabama at Birmingham, Birmingham, AL, United States

Background: Viral lower respiratory tract infections (VLRTIs) are a common cause of hospitalization in infants. Abnormalities in lung mechanics before neonatal discharge may predispose to VLRTIs.

Objective: To determine if lung mechanics measured before neonatal discharge are associated with VLRTI-related hospitalizations by 12 months corrected age (CA).

Design/Methods: In a single center prospective observational cohort study, preterm infants born 22-34 weeks gestation with and without lung disease (respiratory distress syndrome [RDS] and/or bronchopulmonary dysplasia [BPD]) and healthy controls (born ≥ 35 weeks' gestation) without lung disease were enrolled. Pulmonary mechanics were measured by iImpulse oscillometry (IOS) at discharge or 40 weeks' PMA using the Tremoflo N-100 Airwave Oscillometry device (Thorasys, Montreal). We collected parent-reported respiratory outcome data using a modified International Study of Asthma and Allergies in Childhood questionnaire, including hospitalizations and reasons for admission, every 6 months until 12 months CA. We excluded children hospitalized for reasons other than VLRTIs. We used logistic regression to determine the strength of the association between VLRTI-related hospitalizations and IOS data adjusted for weight at IOS testing and sex.

Results: We enrolled 577 infants including 94 preterm infants without lung disease (No RDS), 219 preterm infants with RDS but no BPD (RDS no BPD), 124 preterm infants with BPD (BPD), and 140 control infants (Table 1). Forty-eight infants (8.3%) were hospitalized for a VLRTI before 12 months CA. Reactance at 7 Hz (X7), which represents peripheral airway stiffness, and the area under the reactance curve (AX), which represents overall respiratory system stiffness, were associated with VLRTI hospitalization before 12 months CA (p=0.02 and p=0.04, respectively; Table 2, Figure 1). Measures of resistance were not associated with VLRTI hospitalizations. BPD diagnosis (relative risk (RR), 3.91; 95% CI, 3.05-4.77; p< 0.001), RDS with no BPD (RR, 2.16; 95% CI, 1.32-3.00; p=0.01), and preterm with no lung disease (RR, 1.91; 95% CI, 1.00-2.82; p=0.04) were associated with VLRTI hospitalization compared to controls.

Conclusion(s): Lung mechanics measured using IOS before neonatal discharge are associated with VLRTI-related hospitalizations. These data suggest that predisposition to VLRTIs can be estimated using IOS, prematurity, and respiratory diagnoses before neonatal discharge and used for risk stratification and counselling.

Table 1
Baseline characteristics of patient cohort including respiratory diagnoses and hospitalizations.

Table 2
Results of regression analyses for the association between IOS data, respiratory diagnoses, and VLRTI-related hospitalizations.

Figure 1
Forest plot demonstrating results of regression analyses for the association between IOS data, respiratory diagnoses, and VLRTI-related hospitalizations.