Association between influenza vaccination and mortality risk during influenza epidemic periods and summer periods
| Sets of confounders | Multivariable regression analysis | Propensity score matching | Propensity score regression analysis | |||
| Influenza epidemic | Summer | Influenza epidemic | Summer | Influenza epidemic | Summer | |
| Model 1# | 0.81 (0.66–1.01) | 1.15 (0.98–1.36) | 0.79 (0.63–0.94) | 1.08 (0.95–1.23) | 0.79 (0.64–0.98) | 1.11 (0.94–1.30) |
| Model 2¶ | 0.59 (0.48–0.73) | 0.87 (0.73–1.02) | 0.60 (0.48–0.73) | 0.85 (0.73–0.97) | 0.57 (0.46–0.71) | 0.82 (0.70–0.97) |
| Model 3+ | 0.58 (0.46–0.72) | 0.84 (0.71–1.00) | 0.56 (0.44–0.71) | 0.81 (0.69–0.94) | 0.56 (0.45–0.69) | 0.80 (0.68–0.95) |
Data are presented as odds ratio (95% confidence interval). #: included observed demographics (age, sex); ¶: included age, sex and prior healthcare use (number of general practitioner (GP) visits); +: included age, sex, prior healthcare use, comorbidity status (cardiovascular and pulmonary comorbidity, diabetes mellitus and malignancies), and medication use. Prior healthcare use was classified into four categories: <6 GP visits, 6–10 visits, 11–15 visits and >15 visits.