Characteristic | Difference in average adjusted symptom severity score2 | Standard error | P-value |
---|---|---|---|
Age (years) (ref.: 18–49) |  |  |  |
  50-64 | −0.19 | 0.35 | 0.51 |
  ≥ 65 | −3.08 | 0.49 | < 0.0001 |
Female gender | 0.99 | 0.18 | < 0.0001 |
Days elapsed between symptom onset and enrollment date (ref.: ≥ 7) |  |  |  |
  5-6 | 0.06 | 0.28 | 0.82 |
  3-4 | 0.04 | 0.26 | 0.87 |
  1-2 | −0.27 | 0.27 | 0.31 |
  0 | −2.45 | 0.53 | < 0.0001 |
Number of ambulatory care visits in the past five years | 0.01 | 0.001 | < 0.0001 |
Influenza infection 3 | 1.73 | 0.36 | < 0.0001 |
Vaccinated against influenza | −0.39 | 0.24 | 0.11 |
Total cholesterol (mg/dL) (ref.: < 200) | Â | Â | Â |
  200-239 | 0.67 | 0.19 | 0.0006 |
  ≥ 240 | 0.46 | 0.32 | 0.15 |
Body mass index (kg/m2) (ref.: < 25) | Â | Â | Â |
  25-29 | 0.27 | 0.24 | 0.27 |
  ≥ 30 | 0.61 | 0.22 | 0.005 |
Smoking (ref.: Never) | Â | Â | Â |
  Current | 0.63 | 0.23 | 0.006 |
  Former | 0.73 | 0.19 | < 0.0001 |
Interaction: Age x influenza | Â | Â | Â |
  50-64 × influenza infection | 0.23 | 0.72 | 0.75 |
  ≥ 65 × influenza infection | 4.21 | 1.37 | 0.002 |
Interaction: Age × influenza vaccination |  |  |  |
  50-64 × vaccinated | −0.48 | 0.41 | 0.24 |
  ≥ 65 × vaccinated | 1.45 | 0.57 | 0.01 |
Interaction: Influenza infection x influenza vaccination | 0.92 | 0.68 | 0.17 |
Interaction: Age x influenza infection x influenza vaccination | Â | Â | Â |
  50-64 x influenza infection × vaccinated | −1.02 | 1.11 | 0.36 |
  ≥ 65 × influenza infection × vaccinated | −6.75 | 1.68 | < 0.0001 |