Our study aims to estimate influenza-attributable years of life lost (YLL) in older adults in subtropical Hefei, China from 2012-2017 based on a competing risks approach.
The Quasi-Poisson model was fitted to weekly number of all-cause deaths by 5-year age groups for older adults ≥60 years of age. The product of weekly influenza-like illness consultation rate and proportions of specimens that tested positive for influenza was taken as the measurement of influenza activity, which was incorporated into the model as an exploratory variable. Excess deaths associated with influenza were calculated by subtracting baseline deaths (setting influenza activity to zero) from fitted deaths. Influenza-attributable YLL accounting for competing risks was estimated using restricted mean lifetime survival analysis.
The annual influenza-attributable YLL was the highest in the 75-79 age group (565 per 100,000 persons, 95% CI 550-580), followed by the 80-84, 70-74, 85-89, 65-69, 60-64 age groups. Influenza A(H3N2) was associated with higher YLL than A(H1N1) and B virus. Influenza-attributable YLL accounted for 1.03%-1.53% of total YLL, and the proportion would be overestimated to 2.91%-7.34% if traditional Kaplan Meier method ignoring competing risks was used.
Although influenza-associated mortality increased with age, influenza-attributable YLL was found to be the highest in the 75-79 age group.

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