Nearly half of deaths among patients hospitalized for flu occur postdischarge
Only 37% of patients who died within 30 days of discharge from an influenza hospitalization had flu listed as a cause of death and this was less likely the longer the time between hospitalization and death, indicating that the link may be underappreciated, according to a recent study.
All-cause mortality is high among patients hospitalized for influenza and almost half of all deaths occur within 30 days after hospital discharge, a study found.
To determine the burden of in-hospital versus post-hospital discharge deaths from flu, researchers assessed data from the Influenza Hospitalization Surveillance Network for the 2010-2011 through the 2018-2019 seasons and linked cases to death certificates. A total of 121,390 hospitalizations with laboratory-confirmed influenza over nine seasons were included in the analysis. Findings were published by Clinical Infectious Diseases on Nov. 4.
Of the cases included, 5.5% resulted in death and 76% of deaths were in patients ages 65 years or older. Most patients (71%) were non-Hispanic White, 52.2% were female, and 34% had at least four underlying medical conditions. Forty-eight percent of deaths occurred after hospital discharge, with a median of nine days between discharge and death. Older patients and those with underlying medical conditions were more likely to die after discharge. Just 37% of patients who died had influenza listed as a cause of death on their death certificate.
In-hospital deaths had higher proportions of acute codes for influenza as a cause of death compared with postdischarge deaths (53.8% vs. 18.5%), while postdischarge deaths had higher proportions of codes for cardiovascular disease (41.5% vs. 32.4%). Higher proportions of patients died after discharge during seasons when influenza A(H3N2) was predominant compared with other seasons. The greater the length of time between hospitalization and death, the less likely patients were to have influenza listed as a cause of death (53.8% of those who died during hospitalization, 26.9% of those who died within 0 to 9 days postdischarge, and 9.7% of those who died within 10 to 30 days postdischarge).
Limitations include that not everyone hospitalized for influenza was tested for influenza, potentially underestimating the burden of influenza-associated hospitalizations and mortality, the study authors noted. The findings may also not be generalizable to the entire U.S. population.
Overall, “national mortality surveillance systems that rely solely on death certificates could miss up to two thirds of patients in whom influenza may have contributed to death,” the authors wrote. “Incorporating post-discharge outcome monitoring into influenza hospitalization surveillance can improve national estimates and help to better quantify immediate and short term (within 30 days of hospitalization) morbidity and mortality associated with influenza,” they concluded.