A new study indicates that adults ages 65 years and older who are hospitalized with fever or respiratory symptoms during influenza season are less likely to have a provider-ordered influenza test than younger patients.1

The highest rates of hospitalization and death associated with influenza infections are experienced by older adults. To determine whether doctors are adequately testing older adults for influenza when they present with symptoms, Lauren Hartman, MD, an internist at the Vanderbilt University School of Medicine, and her colleagues conducted a study that included 1,422 adults hospitalized with symptoms of acute respiratory illness or non-localizing fever at four hospitals in Tennessee during the influenza seasons from November 2006 to April 2012.

Overall, the researchers found that 28% of study participants underwent provider-ordered influenza testing. Patients who were tested were younger than those not tested (an average age of 58 years versus 66 years) and more likely to have influenza-like illness (71% versus 49%). Influenza-like illness decreased with increasing age: 63% for those aged 18–49, 60% for those aged 50–64, and 48% for those aged 65 or more. Among all patients, younger age and the presence of influenza-like illness were independent predictors of provider-ordered testing.

The study investigators conducted laboratory tests of influenza for all patients, regardless of whether their providers ordered testing. Among the 399 patients with influenza confirmed by these laboratory tests, influenza-like illness was the only significant predictor of provider-ordered testing. Nearly half of patients with confirmed influenza did not have testing ordered by their providers.

“Influenza is a common cause of hospitalization in older adults, but it is often underrecognized,” says Hartman. “It is important that physicians consider influenza in hospitalized older adults, because antiviral treatment is beneficial if given early, and so spread to other vulnerable patients can be prevented.”


  1. Hartman L, Zhu Y, Edwards KM, et al. Underdiagnosis of influenza virus infection in hospitalized older adults. J Am Geriatr Soc. Published online in advance, January 17, 2018; doi: 10.1111/jgs.15298.