Department of Social and Political Sciences, Bocconi University, Milan, Italy.
SDA Bocconi School of Management, Centre for Research on Health and Social Care Management, Milan, Italy.
BMC Infect Dis. 2024 Feb 20;24(1):227. doi: 10.1186/s12879-024-09071-z.
Influenza and flu-like syndromes are difficult to monitor because the symptoms are not specific, laboratory tests are not routinely performed, and diagnosis codes are often lacking or incompletely registered in medical records. This may result in an underestimation of hospital admissions, associated costs, and in-hospital mortality. Therefore, this study aimed to estimate the public health and economic burden of hospitalisations associated with influenza in Italy, at the national and regional levels.
This 11-year retrospective study included patients admitted to hospitals for influenza or diagnoses associated with influenza (including respiratory and cardiocirculatory conditions) from 2008/09 to 2018/19. Data on hospitalisations were extracted from the Italian Hospital Discharge Records. Information on weekly influenza-like syndrome incidence and weekly average temperature were used to estimate the burden of influenza in terms of hospital admissions in every Italian region and for different age groups by applying a negative binomial model. The model was also applied to estimate in-hospital mortality and the total costs of influenza and influenza-like hospital admissions.
Over the study period, in addition to 3,970 average seasonal admissions coded as influenza, we estimated an average of 21,500 excess hospitalization associated with influenza per season, which corresponds to 36.4 cases per 100,000. Most of the excess hospitalisations concerned older individuals (> 65 years) and children (0-4 years) with 86 and 125 cases per 100,000, respectively. Large variations were observed across regions. Overall, the total estimated hospital burden associated with influenza (including respiratory and cardiocirculatory conditions) was approximately €123 m per year. While the in-hospital mortality for admissions with a primary diagnosis of influenza was very low (~ 150 cases per season), cases increased dramatically for primary diagnoses of influenza and pneumonia (about 9,500 cases per season). The average seasonal in-hospital deaths attributable to influenza were equal to 2,775 cases.
Our findings suggest a remarkable underestimation of the burden of influenza, mostly in the older population but not neglectable in younger individuals. Our results may aid the management of current and future flu seasons and should be used for policy making (e.g., vaccine strategies) and operation management choices (e.g., planning and staffing beds during influenza peaks). Overall, the present study supports the need for increased testing for influenza in Italy to tackle the current underestimation of influenza burden.
流感和类流感综合征难以监测，因为其症状不具有特异性，通常不进行实验室检测，且在医疗记录中诊断代码往往缺失或记录不完整。这可能导致对住院人数、相关费用和住院死亡率的低估。因此，本研究旨在评估意大利全国和地区层面因流感住院的公共卫生和经济负担。
这是一项回顾性研究，纳入了 2008/09 年至 2018/19 年期间因流感或与流感相关的诊断（包括呼吸道和心血管疾病）而住院的患者。从意大利住院记录中提取了住院数据。利用每周流感样综合征发病率和每周平均温度信息，应用负二项模型估算了意大利各地区不同年龄组流感住院负担。该模型还用于估算流感和流感样综合征住院的院内死亡率和总费用。
在研究期间，除了每年平均 3970 例季节性流感住院外，我们还估计每个季节平均有 21500 例与流感相关的超额住院，相当于每 10 万人中有 36.4 例。大多数超额住院发生在年龄较大的人群（>65 岁）和儿童（0-4 岁），分别为每 10 万人中 86 例和 125 例。各地区差异较大。总体而言，每年与流感相关的总住院负担（包括呼吸道和心血管疾病）约为 1.23 亿欧元。尽管流感住院的主要诊断的院内死亡率非常低（~每年 150 例），但流感和肺炎的主要诊断病例数显著增加（每年约 9500 例）。每年归因于流感的平均季节性院内死亡人数为 2775 例。
本研究结果表明，流感负担存在显著低估，主要是在老年人群中，但在年轻人群中也不容忽视。我们的结果可以为当前和未来流感季节的管理提供帮助，并应用于制定政策（如疫苗策略）和运营管理决策（如流感高峰期的床位规划和人员配置）。总体而言，本研究支持意大利增加流感检测，以解决当前对流感负担的低估问题。
