Comparison of bronchiolitis pathogens and disease severity in infants with bronchopulmonary dysplasia receiving RSV prophylaxis and infants with neuromuscular impairment

Introduction: Acute bronchiolitis is the most common lower respiratory tract infection in children under the age of two in both developed and developing countries. Studies have shown that acute bronchiolitis is usually caused by viruses, with respiratory syncytial virus (RSV) being the most common one. RSV prophylaxis is recommended for infants at high risk for RSV infection who are at increased risk of morbidity and mortality. This study aimed to compare the severity of bronchiolitis requiring hospitalization in infants diagnosed with bronchopulmonary dysplasia (BPD) who received RSV prophylaxis and in infants with neuromuscular impairment, and to evaluate the necessity of RSV prophylaxis in children with neuromuscular impairment. Materials and Methods: This study is a single-center, retrospective, observational clinical study. In this study, infants aged 0–24 months who were admitted to the hospital with a diagnosis of moderate to severe acute bronchiolitis at Ankara Bilkent City Hospital between September 1, 2022, and March 31, 2023, and who either had BPD and received RSV prophylaxis or had neuromuscular impairment were included. Sociodemographic characteristics, clinical, laboratory, and radiological findings, length of hospital stay, oxygen requirements, additional treatments received, and complications were compared between the groups. Results: In this study, 41 infants with BPD who received RSV prophylaxis and 61 infants with neuromuscular impairment were included. RSV positivity was detected in 39.3% of patients with neuromuscular impairment and in 17.1% of those with BPD, which was statistically significant (p = 0.029). The median age was 7.5 months (1.0–24.0) in the neuromuscular group and 7 months (0–20.5) in the BPD group. Hospitalization duration was significantly longer in the neuromuscular group compared to the BPD group: for general ward (median 11 vs. 6.5 days; p < 0.001), intensive care unit (median 12 vs. 4 days; p = 0.031), and total hospitalization (median 13 vs. 9 days; p < 0.001). Intubation was required in 23% of the neuromuscular patients, whereas none of the BPD patients required intubation (p = 0.003). Tracheostomy for respiratory support was needed in 29.5% of the neuromuscular group and in 7.3% of the BPD group (p = 0.014). The median duration of oxygen requirement was significantly longer in the neuromuscular group (12.0 [2.0–132.0] vs. 6.0 [1.0–70.0] days; p < 0.001). Antibiotic use was reported in 90.2% of neuromuscular patients and 73.2% of BPD patients (p = 0.047). The median duration of intravenous fluid therapy was 5.0 days (1.0–40.0) in the neuromuscular group and 4.0 days (1.0–15.0) in the BPD group (p = 0.021). Complications related to disease or treatment occurred in 32.8% of neuromuscular patients, while no complications were reported in the BPD group (p < 0.001). When infants with neuromuscular impairment were grouped as RSV PCR positive (n = 24) and RSV PCR negative (n = 37), no statistically significant differences were observed in total length of hospital stay (median 12.5 vs. 15 days; p = 0.329), duration and modality of oxygen support (median 11 vs. 14 days; p = 0.322), or complication rates (20.8% vs. 40.5%; p = 0.186). Conclusion: Infants with neuromuscular impairment were more frequently infected with RSV compared to BPD infants who had received prophylaxis. They experienced longer hospitalizations in both general wards and intensive care units, required more invasive mechanical ventilation, had prolonged needs for oxygen and fluid support, and showed a higher risk of complications. These findings support the necessity of RSV prophylaxis in infants with neuromuscular impairment to protect them from RSV, the leading cause of acute bronchiolitis. Keywords: Acute bronchiolitis, RSV, neuromuscular impairment, bronchopulmonary dysplasia, palivizumab