SAN DIEGO — Most emergency department visits for influenza in the United States are by patients aged 5–49 years who have no other diagnoses, results from a large analysis have shown.
The finding underscores the importance of vaccination in this segment of the population, Kimmie Kohlhase McLaurin reported in a poster session at the 100th International Conference of the American Thoracic Society.
“We don't know much about influenza in this age group,” said Ms. McLaurin, a research analyst for MedImmune Inc., which manufactures FluMist, the intranasal vaccine that was approved in 2003 for healthy children and adults aged 5–49 years. “We know a lot more in the young and in the old. That's where our focus has been.”
In a study funded by MedImmune, Ms. McLaurin and her associate, Shelah Leader, Ph.D., analyzed emergency department data from the 1997–2002 National Hospital Ambulatory Medical Care Surveys to identify visits with a primary diagnosis of influenza based on ICD-9 codes 487.0 (influenza with pneumonia), 487.1 (influenza with other respiratory manifestations), and 487.8 (influenza with other manifestations). More than 1.1 million ED visits for influenza occurred during the 6-year study period. Of these, 69% were by patients aged 5–49 years.
Nearly three-quarters of ED visits by this age group (71%) had no secondary diagnoses, and visits were highest among 18–22-year-olds, nonwhites, and females.
January was noted to be the peak month for visits, followed by February, December, and March.
The most common procedures ordered by clinicians were CBC (35%), chest x-ray (26%), pulse oximetry (19%), and administration of IV fluids (14%).
Most visits (84%) resulted in prescriptions for analgesics (43%), cold/flu remedies (30%), and antibiotics (21%).
Reasons for the visit as reported by the patient were fever/chills (47%), cough (33%), myalgia (20%), throat symptoms (17%), flu (14%), vomiting (14%), and headache (12%).
Ms. McLaurin noted that the estimated direct medical costs of the ED visits during this time period were $576 million. The estimate was based on 1999 data published by the Medical Expenditure Panel Survey Household Component.