Multicenter Study of Clinical Features of Sudden-Onset Versus Slower-Onset Asthma Exacerbations Requiring Hospitalization

BACKGROUND: Asthma exacerbations differ in their speed of symptom onset.

OBJECTIVE: To characterize and compare demographic factors, clinical risk factors, and clinical outcomes among hospitalized patients who presented with sudden-onset (≤ 3 h) versus slower-onset asthma exacerbations, across a wide age range.

METHODS: We reviewed the medical records of a random sample of 1,294 patients, ages 2–54 years, admitted in 30 United States hospitals, for acute asthma from January 1999 to May 2000.

RESULTS: Data on duration of symptoms were available for 1,260 (97%) of the patients. Seventy-two patients (6%) had sudden-onset exacerbations. Sudden-onset patients were older than slower-onset patients (30 y vs 19 y, p = 0.03) but did not differ by other sociodemographic characteristics. Markers of chronic asthma severity were similar between the groups. The sudden-onset patients were more likely to present to the emergency department between midnight and 8:00 AM, to require intubation, and to be admitted to the intensive care unit (all p < 0.01). The higher risk of intensive care unit admission remained significant even after adjustment for 6 potential confounders (odds ratio 2.5, 95% confidence interval 1.3–4.9). However, hospital stay was shorter in the sudden-onset patients (2.0 d vs 2.7 d, p = 0.01). There was no difference in peak expiratory flow at hospital discharge.

CONCLUSIONS: The sudden-onset patients were older and they more commonly presented to the emergency department between midnight and 8:00 AM with severe exacerbations that required intubation and intensive care unit admission. However, the sudden-onset group was discharged from the hospital earlier.