Key messages

• Inhaled corticosteroids do not reduce recurrent wheeze or asthma in patients with bronchiolitis.
• Inhaled corticosteroids probably do not reduce hospital readmission.
• Despite the low cost of this intervention, the use of corticosteroids is not cost-effective for bronchiolitis.

What is the evidence.
See evidence matrix  in Epistemonikos later

Three systematic reviews were identified [1],[2],[3], including 11 primary studies [4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14]. All primary studies were randomized trials.

What types of patients were included*

All trials consider only patients with bronchiolitis.

Regarding age, all trials included patients under 24 months. Specifically, one trial included patients aged 9 months or less [8], one trial 42 weeks or less [7] and five trials included patients under 12 months [4],[5],[6],[11],[12],[13]. Mean age was five months, with a range from two to 11 months.

Five trials included only patients with confirmed respiratory syncytial virus [4],[6],[8],[13],[14]. In remaining trials, respiratory syncytial virus confirmation varied from 26 to 83% [5],[7],[10],[11],[12]. One trial did not report viral etiology [9].

The main exclusion criteria were: previous wheeze in six trials [6],[10],[11],[12],[13],[14], prematurity in four trials [4],[8],[10],[12], immunodeficiency in five trials [4],[5],[8],[11],[12], previous use of systemic corticosteroids in five trials [4],[5],[6],[12],[14], and assisted ventilation in five trials [5],[7],[8],[11],[12]. All of the trials excluded patients with chronic respiratory or cardiac illness.

Seven trials included inpatients [4],[6],[8],[9],[10],[11],[14]. Four trials included outpatients [5],[7],[12],[13].

Three trials were multicenter studies [4],[5],[6].

What types of interventions were included*

Seven trials compared inhaled corticosteroids versus placebo [4],[6],[7],[10],[11],[12],[14]. Remaining four trials compared them versus no treatment [5],[8],[9],[13].

Particularly, seven trials used budesonide [4],[7],[8],[9],[10],[11],[13], two used beclomethasone [5],[6], one used fluticasone [12] and one used dexamethasone [14].

In six trials corticosteroids were administered via metered dose inhaler [5],[6],[7],[8],[12],[13]. In remaining five trials, they were nebulized [4],[9],[10],[11],[14].

Regarding intervention length, in two trials it lasted less than 21 days [4],[8], in two it lasted up to 8 weeks [7],[11], in four it lasted three months [5],[6],[12],[13] and in two trials it lasted 4 months [9],[10]. One trial did not report exact intervention length [14].

What types of outcomes
were measured

Systematic reviews reported the following outcomes: recurrent wheeze, asthma, hospital readmission, need of bronchodilator, length of oxygen supplementation, oxygen supplementation at night, symptoms frequency and adverse effects.

Follow-up was three months in one trial [14], six months in one trial [11], a year in six trials [4],[5],[6],[7],[9],[12], two years in two trials [8],[13] and three years in one trial [10].

To whom this evidence does and does not apply

• The evidence presented in this summary applies to inpatients and outpatients under 24 months with bronchiolitis.
• Even though respiratory syncytial virus predominates, it is reasonable to extrapolate results to different viral etiologies.
• Results do not apply to patients with chronic cardiac or respiratory pathologies, because of direct exclusion of these patients in all including trials. 

• As outcomes, we selected recurrent wheeze or asthma, hospital readmission and adverse effects, because they are critical outcomes for decision making. This selection was based on the authors opinion.
• We initially considered including mortality as an outcome, however it was not reported. Considering the absent effect on other outcomes, we believe an effect on mortality is not to be expected. 

• This summary shows there is no benefit in the use of inhaled corticosteroids.
• Regarding adverse effects, we were only able to analyze the outcome of oral candidiasis from one trial [12].
• We identified one systematic review regarding the use of inhaled corticosteroids in asthma which could not identify significant differences in bone density, growth or cortisol levels [15]. This findings are not completely appliable to our analysis, because the review included patients older than 2 years with asthma and intervention length was 2 years or more. 

• Despite corticosteroids being of low cost, if we consider the absence of benefits, it does not correspond to a cost-effective intervention.

• Considering we did not find an effect on recurrent wheeze or asthma or hospital readmission with the use of inhaled corticosteroids, most of patients and physicians should be against the intervention.
• The latter is even more probable considering possible adverse effects, intervention length and estimated cost, and difficulties associated to administration via aerochamber or nebulization.

Differences between this summary and other sources

• The present summary reaches coincident conclusions to the included systematic reviews.
• The American Academy of Pediatrics guideline about diagnosis, management and prevention of bronchiolitis does not review the use of inhaled corticosteroids in particular [16].
• The United Kingdom National Institute for Health and Care Excellence (NICE) guideline presents a specific recommendation against the use of inhaled corticosteroids for bronchiolitis [17]. 

• Given the certainty of the evidence, the probability of future research changing conclusions of this summary is low. 
• During the redaction of this summary, we identified two additional systematic reviews on the use of inhaled corticosteroids [18],[19]. These were not included, because they did not differentiate the inhaled route of administration from systemic routes (oral, intravenous or intramuscular). Through this reviews, we found only two additional randomized trials not included in the present summary [20],[21]. The analyzed systematic reviews in this summary did not included those trials, because the intervention length was shorter than required according to their inclusion criteria.
• We did not identified ongoing studies in the International Clinical Trials Registry Platform (World Health Organization) regarding the use of inhaled corticosteroids in bronchiolitis.
• In PROSPERO International prospective register of systematic reviews we identified one ongoing systematic review including the use of inhaled corticosteroids in bronchiolitis [22].