Impact of Influenza-like Illness on Health-Related Quality of Life in Japanese Adults

OBJECTIVES: The COVID-19 pandemic and the widespread circulation of the Omicron subvariant changed the epidemiology of respiratory infections, necessitating an assessment of the impacts on health-related quality of life in the post-pandemic era. This study investigated the impact of influenza-like illness on health-related quality of life (HRQoL) in Japanese adults.

METHODS: Using the EuroQol 5-Dimensions 5 Levels (EQ-5D-5L) instrument, we conducted an online survey of Japanese adults in March 2024. Participants were recruited from among registered users of a Japanese marketing research company. The first survey included those who had experienced influenza-like illness on the day before the survey. A follow-up survey was conducted 2–3 weeks after the first survey to assess their recovery. Utility values were calculated based on the Japanese value sets of the EQ-5D-5L. The outcome of this study was the difference in utility values (=disutility value) between the first and follow-up surveys. A generalized linear model was constructed to evaluate the association of participants demographics (age, <40 years vs. ≥40 years; gender, male vs. female; education, university graduate vs. non-university graduate; job, full-time worker vs. non-full-time worker), diagnosis (COVID-19, influenza, respiratory syncytial virus), and days since symptom onset (<7 days vs. ≥7 days) with the disutility value.

RESULTS: A total of 207 registered users responded to the first survey (median age, 38 years [interquartile range 28–51.5 years] and 65.2% were male), while 134 also responded to the follow-up survey. Of these 134 respondents, the median disutility value was −0.04 (interquartile range −0.14 to 0.00). There was no statistical association of participant demographics, diagnosis, or days since symptom onset with the disutility value.

CONCLUSIONS: Our study evaluated the disutility value due to influenza-like illness. There was no statistical association with patient demographics or type of diagnosis in Japanese adults.