Netherlands Institute for Health Services Research (Nivel), Utrecht, the Netherlands.
School of Public Health, Nanjing Medical University, Nanjing, China.
J Glob Health. 2023 Jan 27;13:04003. doi: 10.7189/jogh.13.04003.
WHO estimates that seasonal influenza epidemics result in three to five million cases of severe illness (hospitalisations) every year. We aimed to improve the understanding of influenza-associated hospitalisation estimates at a national and global level.
We performed a systematic literature review of English- and Chinese-language studies published between 1995 and 2020 estimating influenza-associated hospitalisation. We included a total of 127 studies (seven in Chinese) in the meta-analysis and analyzed their data using a logit-logistic regression model to understand the influence of five study factors and produce national and global estimates by age groups. The five study factors assessed were: 1) the method used to calculate the influenza-associated hospitalisation estimates (rate- or time series regression-based), 2) the outcome measure (divided into three envelopes: narrow, medium, or wide), 3) whether every case was laboratory-confirmed or not, 4) whether the estimates were national or sub-national, 5) whether the rates were based on a single year or multiple years.
The overall pooled influenza-associated hospitalisation rate was 40.5 (95% confidence interval (CI) = 24.3-67.4) per 100 000 persons, with rates varying substantially by age: 224.0 (95% CI = 118.8-420.0) in children aged 0-4 years and 96.8 (95% CI = 57.0-164.3) in the elderly aged >65 years. The overall pooled hospitalisation rates varied by calculation method; for all ages, the rates were significantly higher when they were based on rate-based methods or calculated on a single season and significantly lower when cases were laboratory-confirmed. The national hospitalisation rates (all ages) varied considerably, ranging from 11.7 (95% CI = 3.8-36.3) per 100 000 in New Zealand to 122.1 (95% CI = 41.5-358.4) per 100 000 in India (all age estimates).
Using the pooled global influenza-associated hospitalisation rate, we estimate that seasonal influenza epidemics result in 3.2 million cases of severe illness (hospitalisations) per annum. More extensive analyses are required to assess the influence of other factors on the estimates (e.g. vaccination and dominant virus (sub)types) and efforts to harmonize the methods should be encouraged. Our study highlights the high rates of influenza-associated hospitalisations in children aged 0-4 years and the elderly aged 65+ years.
世界卫生组织估计，季节性流感流行每年导致 300 万至 500 万例重症病例（住院病例）。我们旨在提高对国家和全球层面流感相关住院估计数的理解。
我们对 1995 年至 2020 年期间发表的英文和中文的估计流感相关住院的文献进行了系统综述。我们共纳入了 127 项研究（其中 7 项为中文）进行荟萃分析，并使用逻辑回归模型分析其数据，以了解五个研究因素的影响，并按年龄组生成国家和全球估计数。评估的五个研究因素是：1）计算流感相关住院估计数的方法（基于率或时间序列回归）；2）结果测量（分为三个信封：窄、中或宽）；3）每个病例是否经过实验室确认；4）估计数是国家级还是国家级以下；5）比率是否基于单一年份还是多年份。
总体而言，每 100000 人中有 40.5（95%置信区间（CI）=24.3-67.4）人因流感相关住院，年龄差异很大：0-4 岁儿童为 224.0（95%CI=118.8-420.0），>65 岁老年人为 96.8（95%CI=57.0-164.3）。总体而言，住院率因计算方法而异；对于所有年龄组，基于比率的方法或单季节计算的比率显著更高，经实验室确认的病例显著更低。国家级住院率（所有年龄组）差异很大，从新西兰的每 100000 人 11.7（95%CI=3.8-36.3）到印度的每 100000 人 122.1（95%CI=41.5-358.4）（所有年龄组估计数）。
使用全球流感相关住院率的合并数据，我们估计季节性流感流行每年导致 320 万例重症病例（住院病例）。需要进行更广泛的分析，以评估其他因素（如疫苗接种和优势病毒（亚型））对估计数的影响，并应鼓励努力协调方法。我们的研究强调了 0-4 岁儿童和>65 岁老年人中流感相关住院的高比率。
