Influenza - Characteristics of hospitalizations with a diagnosis in France from 2012 to 2017
How can we more accurately describe the impact of seasonal flu outbreaks on the hospital system? A study published today by Santé publique France shows that analyzing hospitalizations with a diagnosis of influenza through the PMSI system provides important insights for interpreting influenza surveillance data that are not available through the current surveillance system. This study provides indicators at the national level. The publication of this report is accompanied by a BSP publication presenting indicators at the regional level.
Data from the Program for the Medicalization of Information Systems (PMSI), which tracks activity in the hospital sector, enabled a retrospective descriptive analysis of hospital stays involving a diagnosis of influenza. The study analyzed, on the one hand, variations in hospitalization rates by age across winter seasons, and, on the other hand, differences in severity and impact characteristics among each age group. The results of this study are presented in a report published today.
Over the course of the five winter seasons from 2012–13 to 2016–17, 91,255 hospital stays with a diagnosis of influenza were identified by the PMSI in metropolitan France.The number of hospitalized cases varied significantly from one season to another, with different populations affected depending on the circulating subtype. The proportion of intensive care admissions and the mortality rate among hospitalized cases were fairly stable within each age group across seasons.
Age: An Important Factor in Influenza Hospitalizations
The impact of age is significant:
on case fatality, with a steady increase from 0.5% among cases under 20 years of age to 10% among cases aged 80 and older,
on the frequency of intensive care admissions, which is much higher in the intermediate age groups of 40 to 79 years than in other age groups,
as a factor in lengthening the length of stay, increasing from 3.4 days among the youngest to 11.5 days among those aged 80 and older.
Significant regional disparities
Significant regional disparities were observed, notably with the highest incidence of hospitalizations in southeastern France and a higher incidence of intensive care admissions in the Île-de-France and Centre-Val de Loire regions.
According to the authors, a systematic annual analysis of hospital stays based on the PMSI would provide, at the end of the season, an age-stratified indicator of the epidemic’s impact on the hospital system.
Regional Public Health Bulletins
Variations of this study have been conducted at the regional level. The results will be published in regional Public Health Bulletins either immediately or in the coming weeks. These regional analyses should provide local stakeholders with a better understanding of the different dynamics of influenza epidemics and their impact on the hospital system.
