Introduction: Antiviral therapy may be underutilized in patients at high risk for increased clinical and economic burden (e.g. older adults). We aimed to examine the benefits associated with antiviral treatment of seasonal influenza among treated and untreated Medicare beneficiaries.
Methods: This retrospective study of Medicare Claims Research Identifiable Files identified patients ≥66 years old with an influenza diagnosis in outpatient setting between October 2016-March 2019 (flu seasons 2016-2018). Index date defined as date of first claim with influenza diagnosis; baseline as the 12 months pre-index. Treated patients received antivirals ≤2 days from index. Untreated patients had no antivirals ≤6 months post-index. Treated/untreated patients were 1:1 propensity score matched. Outcomes (death, all-cause and respiratory-related healthcare resource utilization [HCRU] and costs) were assessed until death or up to 6 months post-index. Descriptive statistics were reported; Kaplan-Meier estimation was used for survival over time.
Results: Among 116,901 matched patient pairs, all-cause mortality within 6 months from index diagnosis was 1.6% among treated versus 4.3% among untreated patients. Rates (treated versus untreated) of all-cause inpatient hospitalizations during follow-up were 13.9% versus 22.7% and respiratory-related hospitalizations were 4.2% versus 9.0%. Mean (SD) total all-cause and respiratory-related costs were $9,830 ($18,616.0) and $900 ($4016.4) among the treated, respectively, versus $13,207 ($24,405.1) and $2,024 ($7,623.7) among untreated, respectively. All differences were statistically significant (p < 0.001).
Conclusions: Lack of antiviral treatment is associated with increased mortality, HCRU, and economic burden in older Medicare beneficiaries with seasonal influenza. Future research should investigate whether the choice of antivirals affects influenza burden.
Keywords: I; I00; I1; I10; Medicare; antivirals; cost; hospitalization; influenza; matched analysis; mortality; treatment status.
Previous studies have shown that antiviral drugs help prevent flu-related complications and lower healthcare utilization and costs. However, these previous studies have focused on working aged people with existing health problems. Our study looks at how antiviral treatment can lower the health and financial burden caused by the flu in older adults. Using a Medicare claims database from the 2016–2018 flu season, we identified 116,901 matched (treated versus untreated) patient pairs. All-cause mortality within 6 months from the index diagnosis (defined as the first claim with a flu diagnosis) was 1.6% among treated versus 4.3% among untreated patients. Rates (treated versus untreated) of all-cause inpatient hospitalizations during follow-up (defined as 6 months after the index diagnosis date) were 13.9% versus 22.7% and respiratory-related hospitalizations were 4.2% versus 9.0%. Mean total all-cause and respiratory-related costs were $9,830 and $900 among the treated, respectively, versus $13,207 and $2,024 among untreated, respectively. All differences were statistically significant (p < 0.001). This analysis of older adults with the flu found that prompt antiviral treatment is associated with lower rates of mortality and acute complications, reduced hospitalization, and lower healthcare costs. Use of antiviral treatment for patients at high risk of flu, such as older adults, is warranted.