Recent Increases in Influenza-Related Hospitalizations, Critical Care Resource Use, and In-Hospital Mortality: A 10-Year Population-Based Study in South Korea

• Published in: Journal of clinical medicine Vol. 11; no. 16; p. 4911
• Main Authors: Hong, Tae Hwa, Lee, Hyung Seok, Kim, Nam-Eun, Lee, Kyu Jin, Kim, Yong Kyun, An, Jung Nam, Kim, Joo-Hee, Kim, Hyung Won, Park, Sunghoon
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 21.08.2022; MDPI
• Subjects: Age; Clinical medicine; Comorbidity; Critical care; Diabetes; Drug dosages; Extracorporeal membrane oxygenation; Health facilities; Health insurance; Heart failure; Hospitalization; Hospitals; Influenza; Investigations; Liver diseases; Mortality; Pandemics; Patient admissions; Population; Population-based studies; Seasons; Steroids; Trends; South Korea; influenza; critical care; mortality; hospitalization
• ISSN: 2077-0383; 2077-0383
• DOI: 10.3390/jcm11164911

Background: Long-term trends in influenza-related hospitalizations, critical care resource use, and hospital outcomes since the 2009 H1N1 influenza pandemic season have been rarely studied for adult populations. Materials and Methods: Adult patients from the Korean Health Insurance Review and Assessment Service who were hospitalized with influenza over a 10-year period (2009−2019) were analyzed. The incidence rates of hospitalization, critical care resource use, and in-hospital death were calculated using mid-year population census data. Results: In total, 300,152 hospitalized patients with influenza were identified (men, 35.7%; admission to tertiary hospitals, 9.4%). Although the age-adjusted hospitalization rate initially decreased since the 2009 H1N1 pandemic (52.61/100,000 population in 2009/2010), it began to increase again in 2013/2014 and reached a peak of 169.86/100,000 population in 2017/2018 (p < 0.001). The in-hospital mortality rate showed a similar increasing trend as the hospitalization, with a peak of 1.44/100,000 population in 2017/2018 (vs. 0.35/100,000 population in 2009/2010; p < 0.001). The high incidence rates of both hospitalization and in-hospital mortality were mainly attributable to patients aged ≥60 years. The rate of intensive care unit admission and the use of mechanical ventilation, continuous renal replacement therapy and vasopressors have also increased from the 2013/2014 season. The incidence of heart failure was the most frequent complication investigated, with a three-fold increase in the last two seasons since 2009/2010. In multivariate analysis adjusted for covariates, among hospitalized patients, type of hospitals and 2009 H1N1 pandemic season were associated with in-hospital mortality. Conclusions: We confirmed that the rates of hospitalization, critical care resource use, and in-hospital mortality by influenza have increased again in recent years. Therefore, strategies are needed to reduce infections and optimize resource use with a greater focus on older people.