Comparison of intramuscular betamethasone and oral prednisone in the prevention of relapse of acute asthma.

OBJECTIVE

To compare the relapse rate after a single intramuscular injection of a long acting corticosteroid, betamethasone, with oral prednisone in patients discharged from the emergency department (ED) for acute exacerbations of asthma.

PATIENTS AND METHODS

Patients with acute exacerbations of asthma who were suitable for discharge from the ED were enrolled in a double-blind, randomized, placebo controlled pilot study. At discharge, patients were randomly assigned to receive either intramuscular betamethasone 12 mg and placebo capsules, or a placebo intramuscular injection and prednisone 50 mg daily for seven days. At days 7 and 21, patients were contacted by telephone to determine relapse. Relapse was defined as an unscheduled visit to a physician for treatment of continuing or worsening symptoms of asthma.

RESULTS

One hundred and seventy-one patients were enrolled, of whom 87 were randomly assigned to the betamethasone group and 84 to the prednisone group. Baseline characteristics were matched evenly between the groups, with the exception of asthma duration (15.5 versus 21.2 years, respectively) and use of inhaled corticosteroids (46% versus 64.3% respectively) (P<0.05). Using intention-to-treat analysis, the relapse rates for betamethasone and prednisone at day 7 were 14.9% (13 of 87 patients) and 25% (21 of 84 patients), respectively (P=0.1), and at day 21, the rates were 36.8% (32 of 87 patients) and 31% (26 of 84 patients), respectively (P=0.4). There were no differences in symptom score, peak flows and adverse effects between the two groups at days 7 and 21.

CONCLUSIONS

A single dose of intramuscular betamethasone 12 mg was safe and as efficacious as prednisone in preventing the relapse of acute asthma. There was a trend toward a reduced relapse rate at seven days. In select ED patients discharged for acute asthma, intramuscular betamethasone may be an effective alternative to prednisone.