Table 7. Estimated IgG anti-S-RBD titers of the 110 subjects that were included in both study periods by the mixed effects model using the gender and age variables as predictors.
| Anti-S-RBD IgG | SEM | df | t | P | |
|---|---|---|---|---|---|
| Age group (years) | |||||
| 21–30 (Reference) | 75,481 | 22813.86 | 1.24 | 3.31 | 0.15 |
| 31–40 | -45,880 | 11291.71 | 102 | -4.06 | p<0.001 |
| 41–50 | -30,653 | 7756.05 | 102 | -4.00 | p<0.001 |
| 51–60 | -31,296 | 7828.25 | 102 | -4.00 | p<0.001 |
| 61–72 | -17,121 | 10080.61 | 102 | -1.70 | 0.092 |
| Gender | |||||
| Male | -14,026 | 5058.32 | 102 | -2.77 | 0.0066 |
| Smoking | |||||
| Yes | -6,879 | 7411.99 | 102 | -0.93 | 0.35 |
| Interaction | |||||
| Smoking × Male | 30,411 | 13716.71 | 102 | 2.22 | 0.024 |
SEM, standard error of the mean (explained variance); df, degrees of freedom; t, t-statistic, the ratio of departure of estimated from hypothesized values to standard error; P, probability of difference from zero.