Estimating the burden of influenza-attributable severe acute respiratory infections on the hospital system in Metropolitan France, 2012–2018

Abstract

Background To date, estimating the burden of seasonal influenza on the hospital system in France has been restricted to influenza diagnoses in patients (estimated hospitalization rate of 35/100,000 on average from 2012 to 2018). However, many hospitalizations for diagnosed respiratory infections (e.g. pneumonia, acute bronchitis) occur without concurrent screening for virological influenza, especially in the elderly. Specifically, we aimed to estimate the burden of influenza on the French hospital system by examining the proportion of severe acute respiratory infections (SARI) attributable to influenza. Methods Using French national hospital discharge data from 1/7/2012 to 30/6/2018, we extracted SARI hospitalizations with ICD-10 codes J09-J11 (influenza codes) in main or associated diagnoses, and J12-J20 (pneumonia and bronchitis codes) in main diagnoses. We estimated influenza-attributable SARI hospitalizations during influenza epidemics, as the number of influenza-coded hospitalizations plus the influenza-attributable number of pneumonia- and acute bronchitis-coded hospitalizations using periodic regression and generalized linear models. Additional analyses stratified by age group, diagnostic category (pneumonia and bronchitis), and region of hospitalization were performed using the periodic regression model only. Results The average estimated hospitalization rate of influenza-attributable SARI during the five annual influenza epidemics covered (2013–2014 to 2017–2018) was 60/100,000 with the periodic regression model, and 64/100,000 with the generalized linear model. Over the six epidemics (2012–2013 to 2017–2018), of the 533,456 SARI hospitalizations identified, an estimated 227,154 were influenza-attributable (43%). Fifty-six percent of cases were diagnosed with influenza, 33% pneumonia, and 11% bronchitis. Diagnoses varied between age groups: 11% of patients under 15 years old had pneumonia versus 41% of patients aged 65 and older. Conclusion Compared to influenza surveillance in France to date, analyzing excess SARI hospitalizations provided a much larger estimate of the burden of influenza on the hospital system. This approach was more representative and allowed the burden to be assessed according to age group and region. The emergence of SARS-Cov-2 has led to a change in the dynamics of winter respiratory epidemics. The co-circulation of the three current major respiratory viruses (influenza, SARS-Cov-2, and RSV) and the evolution of diagnostic confirmation practices must now be taken into account when analyzing SARI.

Registered incidence of acute upper respiratory tract infections diagnosed by primary care physicians in Poland – 5-year retrospective analysis of the national health insurance database

“…Similar results were also reported by the authors of other studies [21,22]. The influenza-related burden varies by age and season [28,29,30]. Its prevention may include various interventions [31], particularly vaccinations which showed effectiveness in all age groups, especially among the elderly [32,33,34].…”

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“…Jalasto et al (2022) [ 7 ] delved into the intricate interplay of occupations, socioeconomic status, and respiratory diseases across different countries, providing a nuanced understanding of the social determinants influencing health outcomes. Estimating the impact of influenza on healthcare systems, Bernadou et al (2023) [ 8 ] offered insights into the strain placed on hospital resources during disease outbreaks. He et al (2023) [ 9 ] focused on the role of air pollution control in mitigating respiratory illnesses, contributing to the broader discourse on environmental factors affecting public health.…”

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Impact of influenza related hospitalization in Spain: characteristics and risk factor of mortality during five influenza seasons (2016 to 2021)

“…Other European studies have also used hospital discharge databases. In France, there are studies of the characteristics of influenza hospitalizations from the 2012–2013 to 2016–2017 influenza seasons ( 3 ) and others estimating the burden of influenza-attributable severe acute respiratory infections on the hospital system in Metropolitan France in different influenza seasons ( 8 , 9 ). Another study in Portugal investigated excess hospitalizations and mortality associated with seasonal influenza from 2008 to 2018 ( 10 ), while in Norway, ( 11 ) studied the burden of medically attended influenza from 2008 to 2017.…”