TABLE 4

Treatment and Illness Severity of Hospitalized Patients by Influenza Type

TreatmentInfluenza Typea
Seasonal A (n = 2645)Influenza B (n = 1510)Unadjusted OR/PAdjusted OR/Pb
Antiviral
 Antibiotic400/2643 (15.1)202/1508 (13.4)0.87 (0.72–1.04)
Measures of illness severity1913/2640 (72.5)1050/1508 (69.6)0.87 (0.76–1.00)
Respiratory complications
 Croup101 (3.8)51 (3.4)0.88 (0.62–1.24)
 Pneumonia (radiologically confirmed)595 (22.5)364 (24.1)1.09 (0.94–1.27)
Extrarespiratory complications
 Myositis18 (0.7)101 (6.7)10.46 (6.31–17.35)6.95 (4.15–11.64)
 Myocarditis6 (0.2)6 (0.4)1.75 (0.56–5.45)
 Hepatitis24 (0.9)22 (1.5)1.61 (0.90–2.89)
 Meningitis6 (0.2)4 (0.3)1.17 (0.33–4.15)
 Encephalitis42 (1.6)36 (2.4)1.51 (0.97–2.37)
 Length of hospital stay, median (IQR), d3.0 (2.0–5.0)3.0 (2.0–5.0)0.60
Mortality
 Attributable to influenza10 (0.4)16 (1.1)2.82 (1.28–6.23)2.65 (1.18–5.94)
 All-cause10 (0.4)18 (1.2)3.18 (1.46–6.90)2.95 (1.34–6.49)
 Admitted to ICU337 (12.7)190 (12.6)0.99 (0.82–1.19)
 Required mechanical ventilationc212 (62.9)124 (65.3)1.11 (0.76–1.61)
 Required extracorporeal membrane oxygenationc7 (2.1)6 (3.2)1.54 (0.51–4.64)
 Length of ICU stay, median (IQR), dc3.0 (1.0–6.5)3.0 (1.0–7.0)0.62
  • —, adjusted OR or P was not calculated.

  • a Data are n (column %) unless otherwise indicated; where fractions are shown, denominator is the number of cases with data available.

  • b Adjusted for age group and health status.

  • c Denominator of the percentage is the number of ICU admitted cases.