The Burden of Seasonal Influenza and Its Potential Complications Among Older Japanese Adults: A Real-World Database Study

Background

Seasonal influenza may lead to severe complications, including respiratory and cardiovascular disease, that result in considerable healthcare resource utilization (HCRU) and mortality, particularly in older individuals. This real-world study assessed the burden of influenza and its potential complications in older Japanese adults.

Methods

This retrospective claims database analysis (April 2015 to June 2019) included insured individuals aged ≥ 60 years at the start of four consecutive influenza seasons in Japan (October 1 to April 30). The primary endpoint was the incidence of influenza-related emergency room (ER) and outpatient visits, the incidence of hospitalizations, the probability of 30-day inpatient mortality, and 60-day medical costs of influenza or its potential complications.

Results

Of 8,974,708 individuals (43.2% male, mean ± standard deviation age 73.8 ± 8.9 years), 370,430 (4.13%) were diagnosed with influenza. Overall, 17.18 (95% confidence interval [CI] 16.32–18.04) and 3893.53 (3880.87–3906.19) per 100,000 individuals had influenza-related ER and outpatient visits, respectively, and 181.50 (178.71–184.28) per 100,000 individuals were hospitalized for influenza. The incidence of influenza-related ER visits and hospitalizations for influenza or potential complications and the probability of 30-day inpatient mortality increased with age.

Conclusions

Seasonal influenza and its potential complications represent a substantial burden that increases with age in Japanese individuals.