Table 3.
Demographic and clinical characteristics of enrolled patients aged ≥60 years with severe acute respiratory infections (SARI) among influenza cases and controls and vaccination status, REVELAC-i, five South American countries, 2013–2017 (n = 6037).
| Variable | Cases n = 1524 n (%) |
Controls n = 4513 n (%) |
p-value* | Vaccinated n = 2793 n (%) |
Unvaccinated n = 3244 n (%) |
p-value* |
|---|---|---|---|---|---|---|
| Age in years | ||||||
| 60–70 | 463 (30) | 1217 (27) | 0.03 | 680 (24) | 1000 (31) | <0.001 |
| 71–80 | 494 (32) | 1556 (34) | 1006 (36) | 1044 (32) | ||
| ≥80 | 567 (37) | 1740 (39) | 1107 (40) | 1200 (37) | ||
| Country | ||||||
| Argentina | 110 (7) | 303 (7) | <0.001 | 162 (6) | 251 (8) | <0.001 |
| Brazil | 272 (18) | 725 (16) | 646 (23) | 351 (11) | ||
| Chile | 849 (56) | 2901 (64) | 1834 (66) | 1916 (59) | ||
| Colombia | 88 (6) | 221 (5) | 49 (2) | 260 (8) | ||
| Paraguay | 205 (13) | 363 (8) | 102 (4) | 466 (14) | ||
| Year | ||||||
| 2013 | 385 (25) | 1166 (26) | <0.001 | 807 (29) | 744 (23) | <0.001 |
| 2014 | 270 (18) | 931 (21) | 616 (22) | 585 (18) | ||
| 2015 | 316 (21) | 903 (20) | 509 (18) | 710 (22) | ||
| 2016 | 194 (13) | 705 (16) | 364 (13) | 535 (16) | ||
| 2017 | 359 (24) | 808 (18) | 497 (18) | 670 (21) | ||
| Gender | ||||||
| Male | 635 (42) | 2090 (46) | 0.002 | 1317 (47) | 1408 (43) | 0.004 |
| Female | 889 (58) | 2423 (54) | 1476 (53) | 1836 (57) | ||
| ≥one chronic condition | 1189 (80) | 3555 (80) | 0.69 | 2247 (83) | 2497 (78) | <0.001 |
| Asthma | 111 (11) | 283 (9) | 0.15 | 182 (10) | 212 (9) | 0.21 |
| Diabetes | 379 (26) | 1025 (23) | 0.05 | 676 (25) | 728 (23) | 0.13 |
| Respiratory disease | 282 (31) | 924 (34) | 0.04 | 601 (40) | 605 (29) | <0.001 |
| Cardiovascular disease | 279 (32) | 864 (32) | 0.73 | 558 (35) | 585 (30) | <0.001 |
| Liver disease | 24 (2) | 78 (2) | 0.82 | 37 (1) | 65 (2) | 0.04 |
| Renal disease | 134 (10) | 433 (11) | 0.43 | 287 (12) | 280 (9) | 0.007 |
| Obesity | 87 (7) | 264 (7) | 0.99 | 162 (7) | 189 (7) | 0.99 |
| Immune disease | 65 (5) | 235 (7) | 0.16 | 123 (6) | 177 (7) | 0.19 |
| Annual influenza vaccination** | 568 (37) | 2225 (49) | <0.001 | – | – | |
| Positive influenza case | – | – | 568 (20) | 956 (29) | <0.001 | |
| Days from illness onset to specimen collection | ||||||
| 0–2 | 619 (41) | 1977 (44) | 0.08 | 1237 (44) | 1359 (42) | 0.02 |
| 3–5 | 615 (40) | 1697 (38) | 1075 (38) | 1237 (38) | ||
| 6–10 | 290 (19) | 839 (19) | 481 (17) | 648 (20) | ||
| Admitted to ICU | 282 (19) | 852 (20) | 0.85 | 529 (19) | 605 (20) | 0.58 |
| Deceased | 192 (13) | 557 (13) | 0.86 | 291 (11) | 458 (15) | <0.001 |
*
X2 test.
**
Received influenza vaccination in concurrent season, regardless prior season.