Comparison of influenza hospitalization outcomes among adults,older adults,and octogenarians: a US national population-based study

ObjectivesThis study sought to more fully elucidate the age-related trends in influenza mortality with a secondary goal of uncovering implications for treatment and prevention.MethodsIn this retrospective cohort analysis of data from the Nationwide Readmission Database, patients with influenza as a primary or secondary discharge diagnosis were separated into three age groups: 55 638 adults aged 20–64 years, 36 862 adults aged 65–79 years and 41 806 octogenarians aged ≥80 years. Propensity score (PS) weighting was performed to isolate age from other baseline differences. Crude and PS-weighted hazard ratios (HR) were calculated from the in-hospital all-cause 30-day mortality rate. Admission threshold bias was minimized by comparison of influenza with bacterial pneumonia mortality.ResultsAdults aged 20–64 years experienced higher in-hospital 30-day mortality compared with older adults aged 65–79 years (HR 0.66; 95% CI 0.55–0.79). Octogenarians had the highest mortality rate, but this was statistically insignificant compared with the adult cohort (HR 1.09; 95% CI 0.94–1.27). This trend was not explained by admission threshold bias: the 30-day mortality rate due to in-hospital bacterial pneumonia increased consistently with age (older adult HR 1.45; 95% CI 1.32–1.59; octogenarian HR 1.99; 95% CI 1.82–2.18).ConclusionsAdults aged 20–64 years and octogenarians were more likely to experience all-cause 30-day mortality during influenza hospitalization compared with older adults aged 65–79 years. These data emphasize the importance of prevention and suggest the need for more tailored treatment interventions based on risk stratification that includes age.