Table 1.
Baseline Characteristics of FLU002 Outpatient and FLU003 Inpatient Cohort Enrollments and Influenza Virus Type/Influenza A Virus Subtype
| FLU002 (N = 3952) | FLU003 (N = 1398) | |||||||
|---|---|---|---|---|---|---|---|---|
| A(H1N1)pdm09 | A(H3N2) | B | A(H1N1)pdm09 | A(H3N2) | B | |||
| Characteristics | n = 1290 | n = 1857 | n = 805 | P Valuea | n = 641 | n = 532 | n = 225 | P Valuea |
| Age, median (25th, 75th), y | 35 (27, 47) | 39 (30, 51) | 42 (34, 53) |
<.0001 | 49 (36, 61) |
67 (49, 77) |
59 (45, 71) |
<.0001 |
| 18–34, % | 50.9 | 39.3 | 28.7 | <.0001 | 22.4 | 13.4 | 12.0 | <.0001 |
| 35–49, % | 30.7 | 34.0 | 40.3 | 30.3 | 12.2 | 19.1 | ||
| 50–64, % | 15.7 | 19.6 | 25.6 | 32.5 | 19.9 | 32.9 | ||
| 65+, % | 2.6 | 7.0 | 5.5 | 14.8 | 54.5 | 36.0 | ||
| Female, % | 52.7 | 52.8 | 49.9 | .36 | 53.2 | 51.9 | 52.4 | .71 |
| Raceb | <.0001 | .08 | ||||||
| Asian, % | 26.7 | 19.5 | 20.0 | 11.1 | 16.7 | 13.8 | ||
| Black, % | 4.6 | 3.3 | 3.4 | 7.3 | 9.0 | 7.6 | ||
| White/other, % | 68.7 | 77.1 | 76.6 | 81.6 | 74.2 | 78.7 | ||
| BMI, median (25th, 75th), kg/m2 | 24.6 (21.8, 28.1) | 24.8 (22.0, 28.1) | 25.1 (22.5, 28.8) | .03 | 26.2 (23.0, 30.6) | 26.3 (22.7, 31.3) | 26.0 (22.9, 30.5) | .62 |
| Smoker, % | 19.3 | 17.9 | 21.4 | .12 | 29.4 | 16.3 | 19.1 | <.0001 |
| Pregnant, % of women aged ≤45 y | 3.3 | 3.7 | 3.5 | .94 | 24.8 | 23.5 | 38.5 | .16 |
| Vaccination in past 12 mo, % | 13.9 | 19.1 | 16.0 | .0005 | 26.2 | 49.6 | 36.4 | <.0001 |
| Antiviral therapy, % | 1.9 | 1.0 | 0.7 | .03 | 79.9 | 78.0 | 70.7 | .03 |
| Time since symptom onset, d | <.0001 | <.0001 | ||||||
| 0–3 d | 84.8 | 87.6 | 77.1 | 21.9 | 35.7 | 22.8 | ||
| 4–5 d | 10.5 | 9.2 | 15.0 | 24.3 | 26.1 | 24.2 | ||
| ≥6 d | 4.6 | 3.2 | 7.8 | 53.8 | 38.2 | 53.0 | ||
| Comorbidities | ||||||||
| Asthma/COPD, % | 5.9 | 5.5 | 4.1 | .19 | 30.3 | 38.9 | 28.4 | .003 |
| Diabetes, % | 3.5 | 3.7 | 4.3 | .58 | 12.8 | 23.9 | 16.4 | <.0001 |
| CVD/liver/renal disease, % | 2.8 | 3.7 | 4.8 | .05 | 21.5 | 38.9 | 34.7 | <.0001 |
| HIV/other immune dysfunction, % | 10.1 | 11.5 | 16.0 | .0002 | 14.0 | 11.3 | 16.9 | .10 |
| Any of above, % | 19.5 | 21.2 | 25.7 | .003 | 54.4 | 73.5 | 65.3 | <.0001 |
Abbreviations: BMI, body mass index; COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease.
aBaseline characteristics for influenza types/subtypes were compared in each study using the 2 degrees of freedom chi-square test for categorical statistics and Kruskal-Wallis rank for continuous variables. For FLU 003, P values are with stratification by ward at enrollment.
bIn FLU002, Asian sites enrolled 20% of patients, Australia 1%, Europe 29%, South America 42%, and North America (USA) 9%. In FLU003, Asian sites enrolled 11% of patients, Australia 13%, Europe 44%, South America 9%, and North America (USA) 23%.