State Key Laboratory of Organ Failure Research, Department of Biostatistics, School of Public Health, Southern Medical University, Guangzhou, China.
Guangzhou Center for Disease Control and Prevention, Guangzhou, China.
JMIR Public Health Surveill. 2023 Jan 11;9:e42530. doi: 10.2196/42530.
Accurate estimation of the influenza death burden is of great significance for influenza prevention and control. However, few studies have considered the short-term harvesting effects of influenza on mortality when estimating influenza-associated excess deaths by cause of death, age, sex, and subtype/lineage.
This study aimed to estimate the cause-, age-, and sex-specific excess mortality associated with influenza and its subtypes and lineages in Guangzhou from 2015 to 2018.
Distributed-lag nonlinear models were fitted to estimate the excess mortality related to influenza subtypes or lineages for different causes of death, age groups, and sex based on daily time-series data for mortality, influenza, and meteorological factors.
A total of 199,777 death certificates were included in the study. The average annual influenza-associated excess mortality rate (EMR) was 25.06 (95% empirical CI [eCI] 19.85-30.16) per 100,000 persons; 7142 of 8791 (81.2%) deaths were due to respiratory or cardiovascular mortality (EMR 20.36, 95% eCI 16.75-23.74). Excess respiratory and cardiovascular deaths in people aged 60 to 79 years and those aged ≥80 years accounted for 32.9% (2346/7142) and 63.7% (4549/7142) of deaths, respectively. The male to female ratio (MFR) of excess death from respiratory diseases was 1.34 (95% CI 1.17-1.54), while the MFR for excess death from cardiovascular disease was 0.72 (95% CI 0.63-0.82). The average annual excess respiratory and cardiovascular mortality rates attributed to influenza A (H3N2), B/Yamagata, B/Victoria, and A (H1N1) were 8.47 (95% eCI 6.60-10.30), 5.81 (95% eCI 3.35-8.25), 3.68 (95% eCI 0.81-6.49), and 2.83 (95% eCI -1.26 to 6.71), respectively. Among these influenza subtypes/lineages, A (H3N2) had the highest excess respiratory and cardiovascular mortality rates for people aged 60 to 79 years (20.22, 95% eCI 14.56-25.63) and ≥80 years (180.15, 95% eCI 130.75-227.38), while younger people were more affected by A (H1N1), with an EMR of 1.29 (95% eCI 0.07-2.32). The mortality displacement of influenza A (H1N1), A (H3N2), and B/Yamagata was 2 to 5 days, but 5 to 13 days for B/Victoria.
Influenza was associated with substantial mortality in Guangzhou, occurring predominantly in the elderly, even after considering mortality displacement. The mortality burden of influenza B, particularly B/Yamagata, cannot be ignored. Contrasting sex differences were found in influenza-associated excess mortality from respiratory diseases and from cardiovascular diseases; the underlying mechanisms need to be investigated in future studies. Our findings can help us better understand the magnitude and time-course of the effect of influenza on mortality and inform targeted interventions for mitigating the influenza mortality burden, such as immunizations with quadrivalent vaccines (especially for older people), behavioral campaigns, and treatment strategies.
准确估计流感死亡负担对于流感的预防和控制具有重要意义。然而，在通过死因、年龄、性别和亚型/谱系估计与流感相关的超额死亡人数时，很少有研究考虑到流感对死亡率的短期收割效应。
本研究旨在估计 2015 年至 2018 年广州因流感及其亚型和谱系导致的死因、年龄和性别特异性超额死亡率。
基于死亡率、流感和气象因素的每日时间序列数据，使用分布式滞后非线性模型来估计不同死因、年龄组和性别的流感亚型或谱系相关的超额死亡率。
共纳入 199777 份死亡证明。平均每年与流感相关的超额死亡率（EMR）为 25.06（95%经验置信区间[eCI] 19.85-30.16）/100000 人；8791 例死亡中有 7142 例（81.2%）归因于呼吸或心血管死亡（EMR 20.36，95% eCI 16.75-23.74）。60-79 岁和≥80 岁人群的超额呼吸和心血管死亡分别占死亡人数的 32.9%（2346/7142）和 63.7%（4549/7142）。呼吸疾病超额死亡的男女比（MFR）为 1.34（95%置信区间 1.17-1.54），而心血管疾病超额死亡的 MFR 为 0.72（95%置信区间 0.63-0.82）。甲型流感（H3N2）、乙型流感（Yamagata 株）、乙型流感（Victoria 株）和甲型流感（H1N1）导致的平均每年超额呼吸和心血管死亡率分别为 8.47（95% eCI 6.60-10.30）、5.81（95% eCI 3.35-8.25）、3.68（95% eCI 0.81-6.49）和 2.83（95% eCI -1.26 至 6.71）。在这些流感亚型/谱系中，甲型流感（H3N2）对 60-79 岁（20.22，95% eCI 14.56-25.63）和≥80 岁（180.15，95% eCI 130.75-227.38）人群的超额呼吸和心血管死亡率最高，而年轻人则更容易受到甲型流感（H1N1）的影响，其 EMR 为 1.29（95% eCI 0.07-2.32）。甲型流感（H1N1）、甲型流感（H3N2）和乙型流感（Yamagata 株）的死亡率转移为 2-5 天，而乙型流感（Victoria 株）的死亡率转移为 5-13 天。
流感在广州导致了大量的死亡，主要发生在老年人中，即使考虑到死亡率转移也是如此。乙型流感，特别是乙型流感（Yamagata 株）的死亡率负担不容忽视。流感相关的呼吸疾病和心血管疾病超额死亡率存在性别差异，其潜在机制需要在未来的研究中进行探讨。我们的研究结果可以帮助我们更好地了解流感对死亡率的影响程度和时间进程，并为减轻流感死亡负担提供有针对性的干预措施，例如为老年人接种四价疫苗（特别是老年人）、开展行为宣传活动和治疗策略。
