Influenza surveillance systems that focus solely on in-hospital deaths may miss up to 50% of flu-related deaths because many occur post-discharge, according to a study recently published in Clinical Infectious Diseases.
Researchers evaluated data from nine flu seasons (2010 to 2019) using the Influenza Hospitalization Surveillance Network. By linking cases to death certificates, researchers were able to identify patients who died from any cause either during their influenza-related hospital stay or within 30 days post discharge.
Among 121,390 patients hospitalized with confirmed influenza throughout the study period, 5.5% died. Forty-eight percent of these deaths occurred after discharge, typically within nine days, according to the findings. Most deaths (76%) occurred among patients 65 and older, particularly those with underlying medical conditions including cardiovascular disease, chronic lung issues or metabolic disorders.
"Medical providers should be aware of the residual risk for mortality soon after discharge from an influenza-associated hospitalization, particularly among older adults," the researchers wrote. "Influenza surveillance systems should consider capture of post-discharge outcomes to better characterize immediate and short-term impacts of influenza on morbidity and mortality."