Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Jun 8;24(1):572.
doi: 10.1186/s12879-024-09446-2.

The Hospital Burden of Flu in Italy: a retrospective study on administrative data from season 2014-2015 to 2018-2019

Riccardo Cipelli  1 , Serena Falato  2 , Eleonora Lusito  2 , Giovanni Maifredi  3 , Michele Montedoro  4 , Paola Valpondi  5 , Alberto Zucchi  6 , Maria Vittoria Azzi  7 , Laura Zanetta  7 , Maria Rosaria Gualano  8 , Entela Xoxi  9 , Paola Giovanna Marchisio #  10   11 , Silvana Castaldi #  12   11
Affiliations

The Hospital Burden of Flu in Italy: a retrospective study on administrative data from season 2014-2015 to 2018-2019

Riccardo Cipelli et al. BMC Infect Dis. .

Abstract

Background: Every year in Italy, influenza affects about 4 million people. Almost 5% of them are hospitalised. During peak illness, enormous pressure is placed on healthcare and economic systems. This study aims to quantify the clinical and economic burden of severe influenza during 5 epidemic seasons (2014-2019) from administrative claims data.

Methods: Patients hospitalized with a diagnosis of influenza between October 2014, and April 2019, were analyzed. Clinical characteristics and administrative information were retrieved from health-related Administrative Databases (ADs) of 4 Italian Local Health Units (LHUs). The date of first admission was set as the Index Date (ID). A follow-up period of six months after ID was considered to account for complications and re-hospitalizations, while a lookback period (2 years before ID) was set to assess the prevalence of underlying comorbidities.

Results: Out of 2,333 patients with severe influenza, 44.1% were adults ≥ 65, and 25.6% young individuals aged 0-17. 46.8% had comorbidities (i.e., were at risk), mainly cardiovascular and metabolic diseases (45.3%), and chronic conditions (24.7%). The highest hospitalization rates were among the elderly (≥ 75) and the young individuals (0-17), and were 37.6 and 19.5/100,000 inhabitants/year, respectively. The average hospital stay was 8 days (IQR: 14 - 4). It was higher for older individuals (≥ 65 years, 11 days, [17 - 6]) and for those with comorbidities (9 days, [16 - 6]), p-value < 0.001. Similarly, mortality was higher in elderly and those at risk (p-value < 0.001). Respiratory complications occurred in 12.7% of patients, and cardiovascular disorders in 5.9%. Total influenza-related costs were €9.7 million with hospitalization accounting for 95% of them. 47.3% of hospitalization costs were associated with individuals ≥ 65 and 52.9% with patients at risk. The average hospitalisation cost per patient was € 4,007.

Conclusions: This retrospective study showed that during the 2014-2019 influenza seasons in Italy, individuals of extreme ages and those with pre-existing medical conditions, were more likely to be hospitalized with severe influenza. Together with complications and ageing, they worsen patient's outcome and may lead to a prolonged hospitalization, thus increasing healthcare utilization and costs. Our data generate real-world evidence on the burden of influenza, useful to inform public health decision-making.

Keywords: Administrative database; Burden; Comorbidities; Complications; Costs; Hospitalization; Influenza; Local health units; Secondary health care.

PubMed Disclaimer

Conflict of interest statement

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: E. X. have disclosed that in the last two years she took part in advisory boards organized by: Eli Lilly, Regeneron Pharmaceuticals, Diurnal Limited, GSK Spa, Incyte Biosciences Italy Srl, Bristol-Mayers Squibb & Affiliates, Blueprint Medicines Italy Srl, Bayer AG, Takeda Pharmaceutical International AG, Astellas Pharma Europe Ltd, Takeda Italia Spa, Actelion Pharmaceuticals Ltd, Genzyme Europe BV, Gilead Sciences Srl, Sanofi Spa and other Italian and international consulting companies. She disclosed that she was engaged in consulting activities with Gilead Sciences Srl, Zambon Italia, Insmed Italy Srl. For the activities mentioned above, all unrelated to this article, she disclosed to have received fees. M.R. G. have disclosed that she received a fee by Sanofi, for a lecture.R. C., S. F., and E. L. have disclosed that they are employees of IQVIA Solutions SRL. M.V.A. and L. Z. are employees of Sanofi, the manufacturer of influenza vaccines, and may hold shares and/or stock options in the company.The remaining authors declare that they have no competing interests. E. X. have disclosed that in the last two years she took part in advisory boards organized by: Eli Lilly, Regeneron Pharmaceuticals, Diurnal Limited, GSK Spa, Incyte Biosciences Italy Srl, Bristol-Mayers Squibb & Affiliates, Blueprint Medicines Italy Srl, Bayer AG, Takeda Pharmaceutical International AG, Astellas Pharma Europe Ltd, Takeda Italia Spa, Actelion Pharmaceuticals Ltd, Genzyme Europe BV, Gilead Sciences Srl, Sanofi Spa and other Italian and international consulting companies. She disclosed that she was engaged in consulting activities with Gilead Sciences Srl, Zambon Italia, Insmed Italy Srl. For the activities mentioned above, all unrelated to this article, she disclosed to have received fees. M.R. G. have disclosed that she received a fee by Sanofi, for a lecture. R. C., S. F., and E. L. have disclosed that they are employees of IQVIA Solutions SRL. M.V.A. and L. Z. are employees of Sanofi, the manufacturer of influenza vaccines, and may hold shares and/or stock options in the company. The remaining authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
The schematic study design. The study design is shown above. The study period spanned from the 1st October 2014 to 1st April 2019: during this period, any patient hospitalized with a diagnosis of influenza was identified. The study Index Date (ID) corresponded to the first hospitalization due to influenza. From the ID, a 6-months follow-up period was considered for each patient, to account for mortality, re-hospitalization, healthcare resource consumption, direct healthcare costs, and influenza related complications (e.g.: for patients enrolled on 1st April 2019 the follow-up period ended on 1st October 2019). A look-back period of 24 months was considered for each patient to account for comorbidities
Fig. 2
Fig. 2
Hospitalization rates by influenza seasons stratified by age categories
Fig. 3
Fig. 3
Distribution of complications across influenza patients by age categories (a), risk group and sex (b) (a)
See this image and copyright information in PMC

References

    1. CDC, Centers for Disease Control and Prevention Types of Influenza Viruses. About Flu. https://www.cdc.gov/flu/about/viruses/types.htm#:~:text=There%20are%20fo.... Accessed 20 November 2023.
    1. EpiCentro. Influenza epidemiologia in Italia. https://www.epicentro.iss.it/influenza/epidemiologia-italia. Accessed 20 November 2023.
    1. Boccalini S, Fiaschi P, Panatto D, Amicizia D, Lai PL, Gasparini R, Bechini A, Bonanni P. Epidemiologia dell’influenza stagionale negli anziani: Un’analisi dei dati italiani sulla sorveglianza clinico-epidemiologica e virologica. Ital J Public Health. 2017;6:4.
    1. Influenza. (Seasonal). https://www.who.int/news-room/fact-sheets/detail/influenza-(seasonal). Accessed 20 November 2023.
    1. CDC, Centers for Disease Control and Prevention. Epidemiology and Prevention of Vaccine-Preventable Diseases, Chap. 12: Influenza. https://www.cdc.gov/vaccines/pubs/pinkbook/flu.html#impact. Accessed 11 May 2023.

MeSH terms