Table 1.
Comparison of vaccinated and unvaccinated subjects against influenza before and after matching.
| Before Matching | After Matching | |||||
|---|---|---|---|---|---|---|
| Characteristics | Vaccinated | Unvaccinated | p | Vaccinated | Unvaccinated | p |
| n = 4380 | n = 4769 | n = 3935 | n = 3935 | |||
| Age | 86.5 [83.5–90.3] |
86.5 [83.5–90.1] |
0.8 | 86.6 [83.5–90.1] |
86.5 [83.5–90.2] |
0.7 |
| 80–90 years | 3248 (74.2) | 3488 (73.1) | 0.3 | 2919 (74.2) | 2891 (73.5) | 0.5 |
| >90 years | 1132 (25.8) | 1281 (26.9) | 0.3 | 1016 (25.8) | 1044 (26.5) | 0.5 |
| Sex | ||||||
| Female | 2538 (57.9) | 3038 (63.7) | <0.001 | 2356 (59.9) | 2348 (59.7) | 0.9 |
| Male | 1842 (42.1) | 1731 (36.3) | <0.001 | 1579 (40.1) | 1587 (40.3) | 0.9 |
| Pneumococcal vaccination | 154 (3.5) | 74 (1.6) | <0.001 | 83 (2.1) | 73 (1.9) | 0.4 |
| Chronic disease | ||||||
| Stroke | 218 (5.0) | 178 (3.7) | 0.003 | 165 (4.2) | 159 (4.0) | 0.7 |
| Peripheral arterial disease | 287 (6.6) | 234 (4.9) | 0.001 | 227 (5.8) | 227 (5.8) | 1.0 |
| Heart failure | 962 (22.0) | 849 (17.8) | <0.001 | 817 (20.8) | 769 (19.5) | 0.2 |
| Chronic liver disease | 4 (0.1) | 6 (0.1) | 0.6 | 4 (0.1) | 5 (0.1) | 0.7 |
| Diabetes | 528 (12.1) | 481 (10.1) | 0.003 | 453 (11.5) | 437 (11.1) | 0.6 |
| Hypertension | 223 (5.1) | 161 (3.4) | <0.001 | 171 (4.3) | 161 (4.1) | 0.6 |
| Coronary artery disease | 387 (8.8) | 354 (7.4) | 0.01 | 343 (8.7) | 337 (8.6) | 0.8 |
| Respiratory failure | 151 (3.4) | 47 (1.0) | <0.001 | 57 (1.4) | 46 (1.2) | 0.3 |
| Cognitive disorders | 282 (6.4) | 309 (6.5) | 0.9 | 261 (6.6) | 280 (7.1) | 0.4 |
| Parkinson’s disease | 45 (1.0) | 113 (2.4) | <0.001 | 44 (1.1) | 28 (0.7) | 0.06 |
| Chronic kidney disease | 71 (1.6) | 46 (1.0) | 0.005 | 52 (1.3) | 46 (1.2) | 0.5 |
| Psychiatric disorders | 62 (1.4) | 70 (1.5) | 0.8 | 56 (1.4) | 56 (1.4) | 1.0 |
| Neoplasia | 516 (11.8) | 464 (9.7) | 0.002 | 443 (11.3) | 431 (11.0) | 0.7 |
| Other chronic diseases | 197 (4.5) | 151 (3.2) | 0.001 | 150 (3.8) | 149 (3.8) | 1.0 |
| Other neurological diseases | 31 (0.7) | 32 (0.7) | 0.8 | 28 (0.7) | 29 (0.7) | 0.9 |
| Immunosuppression | 87 (2.0) | 88 (1.8) | 0.6 | 74 (1.9) | 76 (1.9) | 0.9 |
| Number of chronic diseases | ||||||
| 0 | 1677 (38.3) | 2219 (46.5) | <0.001 | 1633 (41.5) | 1690 (42.9) | 0.5 |
| 1 | 1651 (37.7) | 1709 (35.8) | <0.001 | 1459 (37.1) | 1451 (36.9) | 0.5 |
| 2 | 782 (17.9) | 629 (13.2) | <0.001 | 643 (16.3) | 602 (15.3) | 0.5 |
| 3 | 290 (6.2) | 212 (4.4) | <0.001 | 200 (5.1) | 192 (4.9) | 0.5 |
| Charlson Comorbidity Index | 5 [4,5] | 5 [4,6] | <0.001 | 5 [4,5] | 5 [4,6] | 0.8 |
| <5 | 1696 (38.7) | 2087 (43.8) | <0.001 | 1625 (41.3) | 1612 (41.0) | 0.8 |
| ≥5 | 2684 (61.3) | 2682 (56.2) | <0.001 | 2310 (58.7) | 2323 (59.0) | 0.8 |
| Deaths | 935 (21.3) | 1149 (24.1) | 0.002 | 827 (21.0) | 943 (24.0) | 0.002 |