Demand on ED resources during periods of widespread influenza activity.

The purpose of this study was to investigate ED resource demand during periods of Centers for Disease Control and Prevention (CDC)-declared widespread influenza activity (WIA). An observational analysis of secondary data describing ED resource demand was performed using computerized ED patient data over a 130-week period. Measures of ED resource utilization were compared during WIA and non-WIA periods. These measures included weekly census; percentage of patients triaged as having fever, infection, or respiratory (flu index) chief complaints; admission rate, ED LOS (length of stay), total bed time (TBT), the number of patients who left the ED without being seen by a physician (LWBS), and ED saturation time. The study included 34 weeks of CDC-designated WIA occurring over 3 distinct periods. During WIA, the flu index was elevated, 23% (95% confidence interval [CI], 20-25) versus 17% (95% CI, 16-17). There was increased resource utilization during WIA periods compared with the non-WIA periods for the following parameters: admission rate (24% [95% CI, 24-25%] versus 23% [23-23%]), ED LOS admitted (296 [95% CI, 280-313] versus 271 [95% CI, 265-277]), ED LOS discharged (162 [95% CI, 156-168] versus 152 [95% CI, 150-154]), ED saturation time (1292 [95% CI, 689-1894] versus 409 [95% CI, 209-609]) and LWBS (31 [95% CI, 19-42] versus 14 [95% CI, 12-15]). Although each WIA period was marked by an initial spike in patient volume, weekly census did not increase (1365 [95% CI, 1297-1433] during WIA versus 1297 [95% CI, 1275-1320] during non-WIA). An association between WIA and greater ED resource demand was observed. A spike in census was observed at the onset of each WIA period. In addition, the flu index increased during WIA, suggesting the use of the ED as a site for syndromic surveillance of WIA onset.