Table 3. Predictors of influenza A/H1N1/Michigan/45/2015-pdm09-like virus antibody titers from multivariable regression for entire cohort (N=168).
| Outcomes from logistic regression | OR (95% CI) | P value |
| A/H1N11 Day 28 Seropositivity (HAI titer ≥ 1:40) | ||
| Frail, ref.=non-frail | 1.16 (0.45-2.97) | 0.754 |
| Age, years | 0.95 (0.91-0.99) | 0.008 |
| Female, ref.=male | 2.84 (1.07-7.51) | 0.036 |
| A/H1N1 log2 Day 0 HAI titers | 2.12 (1.54-2.92) | <0.001 |
| A/H1N1 Day 28 Seroconversion (4-fold rise) | ||
| Frail, ref.=non-frail | 1.17 (0.54-2.54) | 0.698 |
| Age, years | 0.94 (0.91-0.98) | 0.002 |
| Female, ref.=male | 2.76 (1.19-6.43) | 0.019 |
| A/H1N1 log2 Day 0 HAI titers | 0.59 (0.47-0.74) | <0.001 |
| Outcomes from linear regression | Beta (SE) | P value |
| A/H1N1 Log2 Day 28 HAI titers | ||
| Frail, ref.=non-frail | 0.27 (0.22) | 0.233 |
| Age, years | -0.03 (0.01) | 0.001 |
| A/H1N1 log2 Day 0 HAI titers | 0.51 (0.06) | <0.001 |
| A/H1N1 Log2 fold-rise in HAI titers (Day 28/Day 0) | ||
| Frail, ref.=non-frail | 0.05 (0.07) | 0.492 |
| A/H1N1 log2 Day 0 HAI titers | -0.20 (0.02) | <0.001 |
1A/H1N1=A/H1N1/Michigan/45/2015-pdm09-like virus.