Single-center, prospective, randomized, double blind, controlled, comparative, interventional clinical trial, conducted in the hospitalization and the pediatric intensive care units of the Hospital Sant Joan de Déu (Esplugues de Llobregat, Barcelona, Spain).
Time: From November 2011 to April 2014 (last update October 2015). The study was approved by the Ethics Committee of the Sant Joan de Déu Hospital, with EUDRA registration number CT 2011-000337-36. The study was registered at ClinicalTrials.gov with number NCT02571517. Parents received an information sheet and signed written informed consent prior to the inclusion of infants in the study.
Inclusion criteria: patients less than 12 months of age with severe or moderate bronchiolitis. Exclusion criteria: lack of informed consent, inclusion in other clinical trials, minor bronchiolitis or apnea as a main symptom, previous corticoid therapy, and primary immunodeficiency.
Bronchiolitis was defined according to the guidelines of the American Academy of Pediatrics 20066. Patients with a bronchiolitis score BROSJOD ≥ 6moderate to severe crises) were eligible for the study23.
A research team collected parents’ consent, demographic (age, sex, ethnic group) and physical (weight, BROSJOD score, Pediatric Risk of Mortality PRISM-II and underlying disease on admittance) data. The infant was then randomly assigned to receive systemic corticoid therapy (oral or endovenous) or placebo. Patient allocation either to the systemic glucocorticoid therapy group (GCT) or the control group (placebo, non-GCT group) was done by generating a binary series of random numbers (‘random’ function of MS-Excel XP® for Windows®). This procedure generated an equivalent random number of patients in both groups that was only available to the pharmacist who was responsible for preparing the two different treatments. Treatments had the same appearance and only the pharmacist who prepared them knew their composition. Patients, clinicians, nurses, and investigators were blind to treatment allocation.
Daily trial interventions in the GCT group were performed using methylprednisolone e.v. in a dose of 1 mg/kg (twice a day, every 12 hours) or with equivalent doses of prednisolone p.o. in a dose of 1.25 mg/kg (twice a day, every 12 hours). In the non-GCT group (placebo), the treatment contained intravenous sodium chloride (NaCl) 0.9%. or 5% oral glucose sodium chloride (twice a day, every 12 hours).
Date range for participant recruitment was from November 2011 to April 2014. Patients follow-up included one month after the trial inclusion day, and the last patient follow-up finished on October 2015.
Trial intervention was for a maximum of 7 days in accordance with previous studies reporting an improvement in the inflammatory response24-26. When patients improved sufficiently within the first days so as to receive hospital discharge, they were removed from the study.
Apart from the intervention of the trial, all patients were treated as follows: patients under conventional mechanical ventilation (MV) were treated with inhaled salbutamol on demand (auscultation with bronchospasm, or prolonged expiration). Patients with noninvasive ventilation (NIV) were tested for bronchodilator treatment at time of admission. Adrenaline or salbutamol were administered depending on patient age (< 6 months or > 6 months, respectively). If the BROSJOD score decreased 2 or more points after treatment, then the bronchodilator treatment was continued every 4-6 or 8 hours.
Common analytical data were recorded, including lymphocytes, leukocytes, and neutrophils. Lymphocyte subsets (CD4 and CD8) were determined with multiparametric flow cytometry in whole blood. Interleukins and IFNγ were assessed by means of solid phase enzyme-labelled chemiluminescent immunometric assays. Tests for reference values were performed following the manufacturer’s procedures. The etiology of bronchiolitis was determined by multiplex protein chain reaction in respiratory samples.
The main outcomes, measured at baseline and day 7 (end of intervention), consisted of: a) levels of lymphocyte subsets, b) levels of IL-2, IL-12, and IFNγ, and c) levels of IL-4 and IL-10. Although sample size was not calculated for this, secondary outcomes related with the clinical response were recorded and compared when possible: need for PICU admission; length of PICU stay and total length of stay (LOS); occurrence of community-acquired bacterial infection, or nosocomial infection; duration of inotropes, MV, NIV, and high flow nasal cannula (HFNC); need for other rescue breathing-treatments (nitric oxide, high frequency mechanical ventilation, extracorporeal membrane oxygenation); need for continuous renal replacement therapy; occurrence of multiple organ failure; and in-hospital mortality at 28 days.
Considered deviations from the protocol: consent not correctly done or not done; non-compliance with the inclusion or exclusion criteria; lack of clinical or analytical data at the baseline visit or performed outside the established period; failure of the study blind; action performed by a researcher who is not the one indicated; inadequate drug or blind doses.
Data were introduced on a clinical record form and were treated as strictly confidential.
Sample size calculation was done according to the statistical program Ene2.0 ®, taking as main variable the existence of differences in the inflammatory response and clinic evolution of patients with moderate-severe bronchiolitis treated with methylprednisolone/prednisolone compared to those receiving placebo. The null hypothesis (H0) was equality of means between the two treatments to be administered (placebo and methylprednisolone/prednisolone) and the alternative hypothesis (H1) was the existence of differences between the two treatments. Considering a power of 80% to detect differences and a level of significance of 0.05, and assuming that the proportion in the reference group was 0.5, the proportion in the experimental group of 0.8, and that the proportion of units experimental in the reference group with respect to the total was 50% it was be necessary include 39 patients in each group according to the results of the treatment with systemic corticosteroids from previous studies already commented.
After an exploratory analysis, sample size was recalculated and a final sample size of 50 patients in each group was obtained. Per-protocol analysis of primary and secondary outcomes was made by means of chi-square for categorical data, t- test for quantitative variables, and Mann-Whitney test for non-parametric data. Normality was assessed through a Kolmogorov-Smirnov test. Paired data were compared through a Wilcoxon signed ranks test. The SPSS® statistical software package 22.0 (SPSS, Inc., Chicago, III) and R software27were used to perform the statistical analyses.