Flu testing at US emergency visits jumped from 3% to 11% from 2013 to 2022

Emergency department sign at hospital

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The proportion of emergency department (ED) visits that triggered influenza testing rose from 2.5% in 2013 to 10.9% in 2022, according to data from the National Hospital Ambulatory Medical Care Survey (NHAMCS).

The results, from researchers at the National Center for Health Statistics (NCHS), are now published as a data brief on the NCHS website.

"Preliminary data from the Centers for Disease Control and Prevention for the 2022–2023 influenza season suggest that 31 million people developed influenza, 360,000 were hospitalized with influenza, and 21,000 died from influenza," the authors wrote.

Greatest increase in infants and young children

The percentage of ED visits with a flu test ordered or provided increased in all age-groups but was highest among infants and children aged 5 years and younger, climbing from 8.6% in 2013 to 23.1% in 2022. Among children aged 6 to 17 years, the proportion with a flu test at ED visits rose from 2.6% to 13.4%. 

To prevent more serious illness, early identification and treatment of influenza is important.

In adults, the percentage of ED visits with a flu test increased from 1.9% to 9.1% in those aged 18 to 44 years, from 1.3% to 8.7% in those aged 45 to 64, and from 1.5% to 9.6% for those aged 65 and older.

The percentages of ED encounters that included a flu test rose for most first-listed reasons for the visit. A flu test was ordered or provided at 16.8% of ED visits for patients with the predominant symptom of fever in 2013, rising to 38.5% in 2022. Likewise, flu tests increased for cough (13.3% to 35.8%). Other common reasons for flu tests were nausea (22.6%), shortness of breath (19.6%), and psychological symptoms (16.7%). 

These percentages were significantly higher than the corresponding proportions in 2013 for nausea (2.2%) and shortness of breath (3.1%). There were no flu tests ordered for psychological symptoms in 2013.

The proportion of ED visits involving a flu test climbed in each of the four US geographic regions during the study period, from 1.6% to 12.9% in the Northeast, 0.4% to 8.4% in the Midwest, 5.0% to 11.4% in the South, and 1.0% to 11.1% in the West.

"To prevent more serious illness, early identification and treatment of influenza is important," the researchers wrote.

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