Efficacy of a small single dose of oral dexamethasone for outpatient croup: a double blind placebo controlled clinical trial

Introduction

Croup (acute laryngotracheobronchitis) is one of the more common childhood respiratory illnesses. Children with moderate to severe airway obstruction are traditionally admitted to hospital for observation. Corticosteroids are now often used for children hospitalised with croup, though the role of steroids for children with less severe illness who are not admitted to hospital has not been studied in depth. A survey of 112 paediatricians and family practitioners from the United States showed that 104 used steroids in children hospitalised with croup, though only 48 used steroids “always.” By contrast, four used steroids “always” for outpatients whereas 36 “never” used them.1 Only one study has looked for benefit from steroids in children not hospitalised with croup.2 The small numbers in that study suggested but could not show conclusively that steroids were of benefit in preventing reattendance with croup.

A recent study from this hospital showed that both nebulised budesonide and oral dexamethasone (0.6 mg/kg) were more effective than placebo in reducing the duration of hospitalisation, croup scores, and need for nebulised adrenaline more than one hour after hospital admission.3 We subsequently showed that a smaller dose of dexamethasone (0.15 mg/kg) was as effective as 0.3 or 0.6 mg/kg.4

Because of the obvious benefits of steroids in children admitted to hospital with croup we proposed that steroids might also benefit children with croup who attend hospital emergency departments but are not admitted. Historically, 1800 to 2000 cases of croup present to our emergency department every year. Three quarters of these children are not admitted, though 10-15% subsequently present to medical care with ongoing croup. We hypothesised that a single oral dose of dexamethasone 0.15 mg/kg would be of benefit to children with milder croup who were not admitted to hospital.

Patients and methods

Children older than 3 months with no other acute or chronic medical problem were eligible for the study if they presented to the emergency department with a diagnosis of croup not severe enough to warrant admission. Croup was defined as the acute onset of inspiratory stridor, chest wall retractions, barking cough, and hoarseness. Generally only children with croup who have stridor and chest wall retractions at rest are admitted to our hospital, those with milder illness being discharged home at the discretion of medical staff. Children were excluded if their families did not have a telephone or had limited English; if they had received steroids of any description in the preceding week; or if they had a pre-existing upper airway condition, a history of prolonged stridor, or a clinical picture suggesting a diagnosis other than croup. Informed written consent was obtained from parents and the study approved by the hospital's ethics committee.

After enrolment the parents completed a questionnaire asking about current and past episodes of croup. Croup score (see box), pulse rate, and respiratory rate at presentation were recorded together with arterial oxygen saturation from a finger probe in room air by means of a Nellcor N-100 pulse oximeter (Nellcor Inc, Hayward, California). Subjects were then randomised to receive either oral dexamethasone 0.15 mg/kg or placebo. Treatments were given double blind.

Seven to 10 days after discharge the children's parents were contacted by telephone. The principal outcome measure was return to medical care with ongoing croup. We also inquired about admissions to hospital with ongoing croup, duration of croup symptoms, duration of viral symptoms, and whether the child had presented to medical care for any other reason.

Mean croup scores were compared by Mann-Whitney U test for non-parametric ordinal data, the remaining normally distributed observations being compared by unpaired Student's t test. We calculated that a sample size of 88 was required to achieve 80% power to show a 90% reduction in the reattendance rate for ongoing croup in steroid treated children ((alpha)=0.05).

Results

One hundred children were enrolled in the trial. Most instances of failure to enrol were due to refusal by parents. Children not enrolled showed no difference from the study population in any variable, including severity of croup. The children's ages ranged from 4 to 122 months, 90 being under 6 years of age. Baseline characteristics of the two treatment groups were similar (table 1). Ninety six of the 100 families were contacted after discharge from the emergency department.

Reattendance with croup after discharge—Eight children, all from the placebo group, subsequently attended a medical facility for croup after discharge (P<0.01; table 2). No child treated with steroids required further medical care for croup.

Other parameters—There was no difference between the groups in admission to hospital with ongoing croup, duration of croup symptoms, duration of viral symptoms, and proportion returning to medical care for any other reason (table 2).

Discussion

In this trial oral dexamethasone 0.15 mg/kg significantly reduced the number of children with mild croup who reattended for medical care with ongoing croup. Meta-analysis of the nine methodologically satisfactory studies conducted up to 1989 suggested that steroid therapy was associated with clinical improvement for children hospitalised with croup.5 Other studies of inhaled and parenteral steroids in children admitted to hospital with croup have all shown benefit from treatment.3 4 6 7 8