## 3 Results
### The Association between the Risk of Stroke and the Influenza Vaccination for Different Age and Sex
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Vaccinated**} \\ \cline{2-6}  & \multicolumn{2}{c}{**Unvaccinated**} & \multicolumn{2}{c}{**1**} & \multicolumn{2}{c}{**2–3**} & \multicolumn{2}{c}{\(\geq\)**4**} \\ \cline{2-6}  & \multicolumn{2}{c}{**Adjusted HR**} & \multicolumn{2}{c}{**Adjusted HR**} & \multicolumn{2}{c}{**Adjusted HR**} & \multicolumn{2}{c}{**Adjusted HR**} \\  & \multicolumn{2}{c}{**(95\% CI)**} & \multicolumn{2}{c}{**(95\% CI)**} & \multicolumn{2}{c}{**(95\% CI)**} & \multicolumn{2}{c}{**(95\% CI)**} \\ \hline Main model \({}^{\dagger}\) & 1.00 & 0.83 (0.75, 0.91) *** & 0.63 (0.57, 0.69) *** & 0.35 (0.32, 0.39) *** & \textless{}0.001 \\ Subgroup effects & & & & & \\ Age, years & & & & & \\
55–64 & 1.00 & 0.58 (0.48, 0.70) *** & 0.48 (0.39, 0.58) *** & 0.27 (0.20, 0.34) *** & \textless{}0.001 \\ \(\geq\)65 & 1.00 & 0.94 (0.83, 1.05) & 0.67 (0.60, 0.75) *** & 0.35 (0.31, 0.39) *** & \textless{}0.001 \\ Sex & & & & & \\ Female & 1.00 & 0.87 (0.76, 1.00) & 0.65 (0.57, 0.75) *** & 0.36 (0.31, 0.42) *** & \textless{}0.001 \\ Male & 1.00 & 0.79 (0.69, 0.90) *** & 0.60 (0.53, 0.69) *** & 0.34 (0.29, 0.39) *** & \textless{}0.001 \\ Diabetes & & & & & \\ No & 1.00 & 0.80 (0.72, 0.90) *** & 0.59 (0.53, 0.66) *** & 0.34 (0.30, 0.38) *** & \textless{}0.001 \\ Yes & 1.00 & 0.89 (0.74, 1.08) & 0.72 (0.60, 0.86) *** & 0.39 (0.32, 0.47) *** & \textless{}0.001 \\ Dyslipidemia & & & & & \\ No & 1.00 & 0.82 (0.74, 0.92) *** & 0.62 (0.56, 0.69) *** & 0.36 (0.32, 0.40) *** & \textless{}0.001 \\ Yes & 1.00 & 0.83 (0.67, 1.03) & 0.63 (0.51, 0.78) *** & 0.33 (0.26, 0.41) *** & \textless{}0.001 \\ AF & & & & & \\ No & 1.00 & 0.82 (0.74, 0.91) *** & 0.62 (0.56, 0.69) *** & 0.35 (0.31, 0.39) *** & \textless{}0.001 \\ Yes & 1.00 & 0.85 (0.64, 1.13) & 0.63 (0.48, 0.83) ** & 0.38 (0.29, 0.50) *** & \textless{}0.001 \\ Antihypertensive & & & & & \\ No (\textless{}28 days) & 1.00 & 0.88 (0.79, 0.99) * & 0.65 (0.58, 0.72) *** & 0.33 (0.29, 0.38) *** & \textless{}0.001 \\ Yes (\(\geq\)28 days) & 1.00 & 0.69 (0.57, 0.85) *** & 0.59 (0.49, 0.70) *** & 0.38 (0.32, 0.45) *** & \textless{}0.001 \\ Diuretics & & & & & \\ No (\textless{}28 days) & 1.00 & 0.87 (0.74, 1.02) & 0.63 (0.53, 0.74) *** & 0.33 (0.27, 0.40) *** & \textless{}0.001 \\ Yes (\(\geq\)28 days) & 1.00 & 0.81 (0.72, 0.91) *** & 0.62 (0.55, 0.70) *** & 0.35 (0.31, 0.40) *** & \textless{}0.001 \\ Beta blocking agents & & & & & \\ No (\textless{}28 days) & 1.00 & 0.78 (0.67, 0.91) ** & 0.65 (0.56, 0.75) *** & 0.31 (0.26, 0.37) *** & \textless{}0.001 \\ Yes (\(\geq\)28 days) & 1.00 & 0.85 (0.75, 0.96) * & 0.61 (0.54, 0.69) *** & 0.37 (0.33, 0.42) *** & \textless{}0.001 \\ Calcium channel blockers & & & & & \\ No (\textless{}28 days) & 1.00 & 0.87 (0.70, 1.08) & 0.56 (0.44, 0.71) *** & 0.33 (0.25, 0.43) *** & \textless{}0.001 \\ Yes (\(\geq\)28 days) & 1.00 & 0.81 (0.73, 0.91) *** & 0.64 (0.57, 0.71) *** & 0.35 (0.32, 0.39) *** & \textless{}0.001 \\ RAA & & & & & \\ No (\textless{}28 days) & 1.00 & 0.70 (0.58, 0.85) *** & 0.52 (0.43, 0.63) *** & 0.25 (0.20, 0.32) *** & \textless{}0.001 \\ Yes (\(\geq\)28 days) & 1.00 & 0.88 (0.79, 0.99) * & 0.67 (0.60, 0.75) *** & 0.39 (0.34, 0.43) *** & \textless{}0.001 \\ Statin drugs & & & & & \\ \textless{}28 days & 1.00 & 0.83 (0.73, 0.93) ** & 0.64(0.57, 0.72) *** & 0.33 (0.29, 0.37) *** & \textless{}0.001 \\
28-365 days & 1.00 & 0.72 (0.58, 0.89) ** & 0.55(0.44, 0.68) *** & 0.37 (0.30, 0.46) *** & \textless{}0.001 \\ \textgreater{}365 days & 1.00 & 0.95 (0.73, 1.24) & 0.66(0.51, 0.86) ** & 0.44 (0.35, 0.57) *** & \textless{}0.001 \\ Metformin drug & & & & & \\ \textless{}28 days & 1.00 & 0.83 (0.74, 0.93) ** & 0.62 (0.55, 0.69) *** & 0.34 (0.30, 0.38) *** & \textless{}0.001 \\
28-365 days & 1.00 & 0.72 (0.53, 0.99) * & 0.51 (0.37, 0.70) *** & 0.31 (0.22, 0.44) *** & \textless{}0.001 \\ \textgreater{}365 days & 1.00 & 0.88 (0.70, 1.10) & 0.72 (0.58, 0.90) ** & 0.42 (0.34, 0.53) *** & \textless{}0.001 \\ Aspirin drug & & & & & \\ \textless{}28 days & 1.00 & 0.87 (0.74, 1.02) & 0.59 (0.49, 0.70) *** & 0.27 (0.22, 0.34) *** & \textless{}0.001 \\
28-365 days & 1.00 & 0.76 (0.64, 0.89) *** & 0.54 (0.46, 0.64) *** & 0.36 (0.30, 0.42) *** & \textless{}0.001 \\ \textgreater{}365 days & 1.00 & 0.90 (0.76, 1.08) & 0.78 (0.66, 0.92) ** & 0.41 (0.35, 0.49) *** & \textless{}0.001 \\ \hline \hline \end{tabular}  
*: \(p\) \(<\)0.05 **: \(p\) \(<\) 0.01 ***: \(p\) \(<\) 0.001 HR: hazard ratio. \({}^{\dagger}\) Main model is adjusted for age, sex, Charlson comorbidity index, diabetes, dyslipidemia, AF, antihypertensives, beta blocking agents, calcium channel blockers, RAA, statin, metformin, aspirin, level of urbanization and monthly income in propensity score.  
\end{table}