Study objective: To identify factors associated with relapse following treatment for acute asthma among adults presenting to the emergency department (ED).
Design: Prospective inception cohort study performed during October 1996 to December 1996 and April 1997 to June 1997, as part of the Multicenter Asthma Research Collaboration.
Setting: Thirty-six EDs in 18 states.
Patients: ED patients, aged 18 to 54 years, with physician diagnosis of acute asthma. For the present analysis, we restricted the cohort to patients sent home from the ED (n = 971), then further excluded patients with comorbid respiratory conditions (n = 32). This left 939 eligible subjects to have follow-up data.
Measurements and results: Two weeks after being sent home from the ED, patients were contacted by telephone. A relapse was defined as an urgent or unscheduled visit to any physician for worsening asthma symptoms during the 14-day follow-up period. Complete follow-up data were available for 641 patients, of whom 17% reported relapse (95% confidence interval, 14 to 20). There was no significant difference in peak expiratory flow rate (PEFR) between patients who suffered relapse and those who did not. In a multivariate logistic regression analysis (controlling for age, gender, race, and primary care provider status), patients who suffered relapse were more likely to have a history of numerous ED (odds ratio [OD] 1.3 per 5 visits) and urgent clinic visits (OR 1.4 per 5 visits) for asthma in the past year, use a home nebulizer (OR 2.2), report multiple triggers of their asthma (OR 1.1 per trigger), and report a longer duration of symptoms (OR 2.5 for 1 to 7 days).
Conclusion: Among patients sent home from the ED following acute asthma therapy, 17% will have a relapse and PEFR does not predict who will develop this outcome. By contrast, several historical features were associated with increased risk. Further research should focus on ways to decrease the relapse rate among these high-risk patients. The clinician may wish to consider these historical factors when making ED decisions.