Critical Influenza and COVID-19—A Comparative Nationwide Case-Control Study

Abstract

IMPORTANCE: Refined knowledge of risk factors for critical influenza and COVID-19 may lead to improved understanding of pathophysiology and better pandemic preparedness. OBJECTIVES: To compare risk-factor profiles of patients admitted to intensive care with critical influenza and COVID-19. DESIGN, SETTING, AND PATIENTS: A nationwide retrospective matched case-control study, including all adults admitted to an ICU in Sweden with influenza or COVID-19 between 2014 and September 2020 and a matched control population (ratio 1:5, patients:controls). MEASUREMENTS AND MAIN RESULTS: Admission to an ICU. The study included 1,873 influenza and 2,567 COVID-19 ICU patients, and 9,365 and 12,835 controls, respectively, matched on sex, age, and geographical region. Influenza patients were older and less likely male, and carried a larger burden of comorbidity and a higher Simplified Acute Physiology Score III score, whereas short-term mortalities were similar when compared to COVID-19 patients. The risk-factor profiles at ICU admission were largely comparable including socioeconomic, psychiatric, and several somatic variables. Hypertension was a strong risk factor in critical COVID-19 patients compared with influenza. Nonglucocorticoid immunosuppressive therapy was associated with critical influenza but not COVID-19. Premorbid medication with statins and renin-angiotensin-aldosterone system inhibitors reduced the risk for both conditions, the opposite was a seen for glucocorticoid medication. Notably, medication with betablockers, oral anticoagulation, and platelet inhibitors reduced the risk of critical COVID-19 but not influenza. CONCLUSIONS: The risk-factor profiles for critical influenza and COVID-19 were largely comparable; however, some important differences were noted. Hypertension was a stronger risk factor for developing critical COVID-19, whereas the use of betablockers, oral anticoagulants, and platelet inhibitors all reduced the risk of ICU admission for COVID-19 but not influenza. Findings possibly reflected differences in pathophysiological mechanisms between these conditions.

Association of Cardiovascular Medications With Adverse Outcomes in a Matched Analysis of a National Cohort of Patients With COVID-19

“…Overall, our observation that the outpatient use of statins, ACEI/ARBs and anticoagulants were protective against adverse outcomes in patients diagnosed with COVID-19 is consistent with a review conducted by Alves et al 52 and previous studies that assessed premorbid use of these classes of cardiovascular medications. 53 , 54 , 55 , 56 , 57 It is important to note, that ours is, to our knowledge, the largest matched, national comparative analysis of cardiovascular medications and COVID-19 outcomes thus far.…”

Comparison of Clinical Characteristics and Outcomes in Intensive Care Units Between Patients with Coronavirus Disease 2019 (COVID-19) and Patients with Influenza: A Systematic Review and Meta-Analysis

“…Most of the data were from retrospective studies, 5,10,[15][16][17][18][19][20][22][23][24][25][26][28][29][30][32][33][34][35][37][38][39][40][41][42][43][44][45][46][47] 2 articles were prospective studies, 31,34 and 3 articles did not specify the type of study. 21,27,36 Four articles specifically studied patients with influenza A, 10,21,31,36 15 articles studied patients with type A/B, 5,15,16,20,[24][25][26][27]30,32,33,…”

Evaluating the efficiency of ELISA, monoplex and multiplex probe‐based real‐time reverse‐transcription PCR assays in the detection of SARS‐CoV‐2 (COVID‐19) and influenza A and B viruses: A cross‐sectional study

“…3 It is well known that Flu disease is responsible for 650,000 deaths annually. 5 In general, children and individuals aged > 65 years are the susceptible groups to Flu infections. 4 Healthcare systems are likely to face overlapping outbreaks of SARS-CoV-2 and influenza.…”

“…Abnormalities caused by the Flu virus is varied from uncomplicated upper respiratory tract disease to complicated illnesses with severe viral pneumonia 3 . It is well known that Flu disease is responsible for 650,000 deaths annually 5 . In general, children and individuals aged > 65 years are the susceptible groups to Flu infections 4 …”

“… 3 It is well known that Flu disease is responsible for 650,000 deaths annually. 5 In general, children and individuals aged > 65 years are the susceptible groups to Flu infections. 4 …”