Predictors of severity and in-hospital mortality in patients with influenza

Submitted: April 3, 2021
Accepted: July 20, 2021
Published: August 10, 2021
Abstract Views: 1232
PDF: 464
Publisher's note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.


Influenza virus is a common agent of acute respiratoty infections during epidemic periods. It is a major cause of morbidity and mortality and represent a significant burden on the healthcare system. We aimed to evaluate predictors of severity and of in-hospital mortality in patients hospitalized with influenza infection. We performed a retrospective cohort study of hospitalized, laboratory confirmed cases of influenza disease in Centro Hospitalar de São João between October 2016-May 2017 and October 2017-May 2018. The endpoints being analysed were severity and in-hospital mortality. A multivariate logistic regression analysis was used to determine independent predictors of severity and of in-hospital mortality. We studied 221 hospitalized influenza infection cases. Mean age 66±16 years, 57.9% were male, thirty-seven patients (16.7%) died in-hospital and 101 patients (45.7%) met severity criteria. C-reactive protein (CRP) was the only independent predictor of severity as well as the only independent predictor of higher in-hospital mortality in patients admitted due to influenza infection. Multivariate-adjusted CRP OR for severity was 1.10, 95% CI 1.06-1.15 per each 10 mg/L increase in CPR and for in-hospital mortality risk the OR was of 1.05, 95% CI 1.01-1.09, p=0.01, per each 10 mg/L increase. Concluding, in patients’ hospital-admitted due to influenza infection CRP was the only predictor of severity with a 10% increased risk of inotropic support/ventilatory support/prolonged hospitalization needs and a 5% increase risk of in-hospital death per each 10 mg/l increase.



PlumX Metrics


Download data is not yet available.


Center for Disease Control and Prevention. Seasonal influenza (flu). Accessed: 01/06/2019. Available from:
Uyeki TM. Influenza. Ann Intern Med 2017;167:ITC33-48.
Bresee J, Hayden FG. Epidemic influenza-responding to the expected but unpredictable. N Engl J Med 2013;368:589. DOI:
European Centre for Disease Prevention and Control. Influenza virus characterisation, summary Europe, September 2018. Stockholm: ECDC; 2018.
Instituto Nacional de Saúde Doutor Ricardo Jorge I.P. [Boletim de Vigilância Epidemiológica da Gripe, Época 2016/2017 - Semana 20].[in Portuguese]. Instituto Nacional de Saúde Doutor Ricardo Jorge I.P., 2017.
Instituto Nacional de Saúde Doutor Ricardo Jorge I.P. [Boletim de Vigilância Epidemiológica da Gripe, Época 2017-2018 - Semana 20].[in Portuguese]. Instituto Nacional de Saúde Doutor Ricardo Jorge I.P., 2018.
Chaves SS, Aragon D, Bennett N, et al. Patients hospitalized with laboratory-confirmed influenza during the 2010-2011 influenza season: exploring disease severity by virus type and subtype. J Infect Dis 2013;208:1305-14. DOI:
Ribeiro AF, Pellini AC, Kitagawa BY, et al. Risk factors for death from Influenza A(H1N1)pdm09, State of Sao Paulo, Brazil, 2009. PLoS One 2015;10:e0118772.
Arriola C, Garg S, Anderson EJ, et al. Influenza vaccination modifies disease severity among community-dwelling adults hospitalized with influenza. Clin Infect Dis 2017;65:1289-97. DOI:
Center for Disease Control and Prevention. Prevent flu. Accessed: 01/06/2019. Available from:
Ghebrehewet S, MacPherson P, Ho A. Influenza. BMJ 2016;355:i6258.
Moscona A. Neuraminidase inhibitors for influenza. N Engl J Med 2005;353:1363-73. DOI:
Cooper NJ, Sutton AJ, Abrams KR, et al. Effectiveness of neuraminidase inhibitors in treatment and prevention of influenza A and B: systematic review and meta-analyses of randomised controlled trials. BMJ 2003;326:1235. DOI:
Dobson J, Whitley RJ, Pocock S, Monto AS. Oseltamivir treatment for influenza in adults: a meta-analysis of randomised controlled trials. Lancet 2015;385:1729. DOI:
Jefferson T, Demicheli V, Rivetti D, et al. Antivirals for influenza in healthy adults: systematic review. Lancet 2006;367:303. DOI:
Hong KW, Cheong HJ, Choi WS, et al. Clinical courses and outcomes of hospitalized adult patients with seasonal influenza in Korea, 2011–2012: hospital-based influenza morbidity & mortality (HIMM) surveillance. J Infect Chemother 2014;29:9–14. DOI:
Canak G, Kovacevic N, Turkulov V, et al. Clinical features, treatments and the outcomes of influenza A (H1N1) 2009 among the hospitalized patients in the clinic for infectious diseases in Novi Sad. Vojnosanit Pregl 2013;70:155–62. DOI:
Baden LR, Swaminathan S, Angarone M, et al. Prevention and treatment of cancer-related infections, version 2.2016, NCCN clinical practice guidelines in oncology. J Natl Compr Canc Netw 2016;14:882-913. DOI:
Vasileva D, Badawi A. C-reactive protein as a biomarker of severe H1N1 influenza. Inflamm Res 2019;68:39–46. DOI:
Zimmerman O, Rogowski O, Aviram G, et al. C-reactive protein serum levels as an early predictor of outcome in patients with pandemic H1N1 influenza A virus infection. BMC Infect Dis 2010;10:288. DOI:
Gao RB, Wang L, Bai T, et al. C-reactive mediating immunopathological lesions: a potential treatment option for severe influenza A diseases. EBioMedicine 2017;22:133–42. DOI:
Liu Q, Zhou YH, Yang ZQ. The cytokine storm of severe influenza and development of immunomodulatory therapy. Cell Mol Immunol 2016;13:3–10. DOI:
Shah SH, Newby LK. C-reactive protein: a novel marker of cardiovascular risk. Cardiol Rev 2003;11:169-79. DOI:

Supporting Agencies

not applicable

How to Cite

Serino, Mariana, Nuno Melo, João Paulo Caldas, Ana Ferreira, David Garcia, and Patrícia Lourenço. 2021. “Predictors of Severity and in-Hospital Mortality in Patients With Influenza”. Monaldi Archives for Chest Disease 92 (1).