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