Acute relapse of asthma following treatment and discharge from the emergency department is a significant problem. Various studies have suggested relapse rates ranging from 11 percent over three days to 30 percent over several weeks. A number of risk factors are associated with relapse. However, many studies have been performed in small patient populations, and their results may not be generalizable. Emerman and associates conducted a multicenter prospective study of patients with asthma who were treated and released from the emergency department to identify the risk factors associated with relapse.

Patients with acute asthma who presented to one of 36 emergency departments in 18 states were eligible for the study. All were treated at the discretion of the emergency physician. The emergency department interview consisted of obtaining an asthma history and a list of trigger factors. Information about treatment and peak expiratory flow rate measurements were obtained in a review of medical records. Follow-up of all patients was conducted by telephone interview two weeks after discharge. At that time, patients were asked if they had sought urgent medical care or if they had any change in medication. Relapse was defined as any urgent or unscheduled medical care provided in any setting in the two-week follow-up period.

Complete follow-up data were compiled for 641 patients. Seventeen percent reported an acute asthma relapse within the follow-up period. More than one third of these patients reported a relapse within the first three days, and more than 50 percent reported a relapse within six days. Overall, major factors such as treatment regimens, emergency department treatment and initial and final peak expiratory flow rates did not differ in patients who experienced a relapse and in those who did not. However, patients who had a relapse were more likely to have a history of hospital admission for asthma, an increased number of urgent medical visits for asthma treatment, use of home nebulizers, symptoms for over 24 hours but less than one week and multiple asthma triggers.

The authors conclude that a substantial number of patients treated in the emergency department for acute asthma experience a relapse within days or weeks. Certain easily identifiable historic features are associated with a high risk of relapse, including a history of more urgent care visits, multiple triggers, longer duration of symptoms and use of home nebulizers. However, peak expiratory flow rate does not predict relapse. Patients at high risk for relapse should be considered for prolonged emergency department treatment or be admitted for closer observation.