Discussion
The main purpose of this study was to determinate the clinical predictors of hospitalization with airway support (“escalated care”) among infants with recurrent wheezing evaluated in the emergency department. Our study shows that prematurity, poor feeding, nasal flaring and/or grunting and previous wheezing were independent predictors of escalated care. The clinical risk score, with a demonstrated high stability and discrimination ability, derived in a non-selected population is used to quantify estimated risk for escalated care in patients with recurrent wheezing during the hospital stay.
Most studies have been focused on predicting hospital admission from the ED or PICU, or using a specific type of NIPPV or mechanical ventilation (6).‍ We have focused our outcome on receipt of escalated care, since these infants needs timely identification due to the risk of developing acute respiratory failure. The clinical use of the risk score must be prospectively validated; it has the potential to individualize recurrent wheezing treatment.
Research of predictive models in infants with bronchiolitis has generally been focused on inpatients, especially infants admitted to PICUs, with relatively small numbers of patients, and only focused on RSV bronchiolitis (6). In a retrospective cohort study with 2722 infants conducted by Freire el al., around 261 (9.6%) received escalated care. Multivariable predictors of escalated care were oxygen saturation, nasal flaring and/or grunting, apnea, retractions, age ≤2 months, dehydration, and poor feeding. However, this study was conducted in children younger than 12 months with their first wheezing episode and excluded infants with comorbidities, limiting their external validity to other subpopulations. Through a non-selected population-based cohort study of 34,270 infants in Ontario, Schun et al. identified the following as predictors of admission: critical care comorbidities (OR 5.33; 95% CI 2.82-10.10), younger age [months] (OR 1.47; 95%CI 1.33-1.61), low income (OR 1.53; 95% CI 1.01-2.34), younger gestational age [weeks] (OR 1.14; 95%CI 1.06-1.22), and emergent presentation (Canadian Triage and Acuity Scale 2) at the index visit (OR 1.55, 95% CI 1.03-2.33). The odds of these outcomes with comorbidities plus ≥2 other predictors were 25 times higher than in infants without predictors (OR 25.1, 95% CI 11.4-55.3) (16). The differences between the risk factors found in these studies compared to our study are due to the differences in the populations studied. While our study included patients with or without comorbidities and who had more than one wheezing episode, Freire’s study focused on low-risk patients in their first wheezing episode. In this sense, our study is complementary to Freire’s study, indicating that variables such as nasal flutter and poor feeding that this study found as predictors also continue to be predictors in recurrent wheezing patients with comorbidities. The aim of our tool is for it to be used by clinicians to guide management decisions. For example, the score would support the outpatient management of premature patients with wheezing without respiratory distress issues or with adequate feeding. Around 25% of hospitalized infants with bronchiolitis receive no evidence-based therapies (17), and the use of the risk score may result in a lower hospitalization rate and lower health-care expenditure. Our risk score employs clinical items in routine use for assessing bronchiolitis.
Our study has limitations. Firstly, since this study was based on a review of medical records, we cannot include other variables such as environmental pollution and genetic factors, and residual confounding cannot be excluded. Secondly, the study was conducted in a tertiary referral hospital, and therefore the patients included represent the high spectrum of severity, limiting the generalization of results to other contexts. However, the similarity of our population in terms of clinical characteristics, risk factors, and seasonality of bronchiolitis in our country with previous reports suggests strength and consistency in our results(18, 19). Thirdly, in our study, we used an immunofluorescent assay to diagnose RSV infections. Although this is widely available and easy to perform, we did not determine the RSV genomic load, and we also did not test for viruses. This may generate a differential misclassification bias, which could have overestimated the true association between RSV isolation and the outcome variable; however, the previous evidence in other populations had confirmed this association being plausible in our results.
Conclusion :
In conclusion, the present study shows that prematurity, poor feeding, nasal flaring and/or grunting, and more than one previous episode of wheezing requiring hospitalization are independent predictors of hospitalization with airway support (“escalated care”) in a population of infants with recurrent wheezing attended to in the ED. A clinical risk score was created based on the odds ratio of each of the identified variables, which appears to be useful for estimating the absolute risk of escalated care within 5 days of admission to the ED; however, external validation is required before this clinical score is applied in general practice in any ED setting.
Abbreviations :
CHD: Congenital heart disease
BPD: Bronchopulmonary dysplasia
PICU: pediatric intensive care unit admission
RSV: Respiratory syncytial virus
NIPPV: non-invasive positive-pressure ventilation
ED: emergency department