Table 1.
Characteristics of Community-Dwelling Adults Aged >65 Years Who Died Within 30 Days of Influenza Testing (n = 6837) During the 2010–2011 to 2015–2016 Seasons in Ontario, Canada
| Characteristic | Influenza-positive (n = 925) | Influenza-negative (n = 5912) | P value | Influenza Vaccinated (n = 3465) | Influenza Unvaccinated (n = 3372) | P valve |
|---|---|---|---|---|---|---|
| Receipt of seasonal influenza vaccine | 424 (45.8%) | 3041 (51.4%) | .002 | 3465 (100.0%) | 0 (0%) | N/A |
| Positive for influenza | 925 (100.0%) | 0 (0%) | N/A | 424 (12.2%) | 501 (14.9%) | .002 |
| Age (y), mean ± SD | 82.58 ± 8.53 | 81.06 ± 8.34 | <.001 | 81.64 ± 8.09 | 80.87 ± 8.66 | <.001 |
| Age group, y | ||||||
| 66–75 | 210 (22.7%) | 1727 (29.2%) | <.001 | 901 (26.0%) | 1036 (30.7%) | <.001 |
| 76–85 | 338 (36.5%) | 2237 (37.8%) | 1370 (39.5%) | 1205 (35.7%) | ||
| ≥86 | 377 (40.8%) | 1948 (32.9%) | 1194 (34.5%) | 1131 (33.5%) | ||
| Male sex | 477 (51.6%) | 3298 (55.8%) | .016 | 1968 (56.8%) | 1807 (53.6%) | .008 |
| Rural residence | 81 (8.8%) | 462 (7.8%) | .528 | 257 (7.4%) | 286 (8.5%) | .266 |
| Neighborhood income quintile | ||||||
| 1 (lowest) | 199 (21.5%) | 1311 (22.2%) | .98 | 732 (21.1%) | 778 (23.1%) | .176 |
| 2 | 201 (21.7%) | 1292 (21.9%) | 770 (22.2%) | 723 (21.4%) | ||
| 3 | 174 (18.8%) | 1064 (18.0%) | 642 (18.5%) | 596 (17.7%) | ||
| 4 | 162 (17.5%) | 1059 (17.9%) | 612 (17.7%) | 609 (18.1%) | ||
| 5 (highest) | 185 (20.0%) | 1155 (19.5%) | 696 (20.1%) | 644 (19.1%) | ||
| Missing information | ≤5 (0.4%) | 31 (0.5%) | 13 (0.4%) | 22 (0.7%) | ||
| Season of specimen collection | ||||||
| 2010–2011 | 99 (10.7%) | 760 (12.9%) | <.001 | 409 (11.8%) | 450 (13.3%) | <.001 |
| 2011–2012 | 42 (4.5%) | 407 (6.9%) | 246 (7.1%) | 203 (6.0%) | ||
| 2012–2013 | 184 (19.9%) | 1091 (18.5%) | 577 (16.7%) | 698 (20.7%) | ||
| 2013–2014 | 129 (13.9%) | 1153 (19.5%) | 696 (20.1%) | 586 (17.4%) | ||
| 2014–2015 | 348 (37.6%) | 1439 (24.3%) | 929 (26.8%) | 858 (25.4%) | ||
| 2015–2016 | 123 (13.3%) | 1062 (18.0%) | 608 (17.5%) | 577 (17.1%) | ||
| Month of specimen collection | ||||||
| November | 15 (1.6%) | 190 (3.2%) | <.001 | 65 (1.9%) | 140 (4.2%) | <.001 |
| December | 203 (21.9%) | 856 (14.5%) | 483 (13.9%) | 576 (17.1%) | ||
| January | 328 (35.5%) | 1469 (24.8%) | 883 (25.5%) | 914 (27.1%) | ||
| February | 140 (15.1%) | 1136 (19.2%) | 660 (19.0%) | 616 (18.3%) | ||
| March | 142 (15.4%) | 1109 (18.8%) | 668 (19.3%) | 583 (17.3%) | ||
| April | 83 (9.0%) | 773 (13.1%) | 485 (14.0%) | 371 (11.0%) | ||
| May | 14 (1.5%) | 379 (6.4%) | 221 (6.4%) | 172 (5.1%) | ||
| Setting of specimen collection | ||||||
| Intensive care unit | 279 (30.2%) | 2120 (35.9%) | <.001 | 1258 (36.3%) | 1141 (33.8%) | .094 |
| Hospital ward | 598 (64.6%) | 3616 (61.2%) | 2100 (60.6%) | 2114 (62.7%) | ||
| Emergency department | 38 (4.1%) | 151 (2.6%) | 87 (2.5%) | 102 (3.0%) | ||
| Physician office | 10 (1.1%) | 25 (0.4%) | 20 (0.6%) | 15 (0.4%) | ||
| Hospitalizations in past 3 years, mean ± SD | 1.68 ± 2.11 | 1.81 ± 2.23 | .079 | 1.71 ± 2.08 | 1.88 ± 2.34 | .001 |
| Physician office visits in past year, mean ± SD | 14.00 ± 10.85 | 15.11 ± 11.78 | .007 | 16.39 ± 11.34 | 13.50 ± 11.81 | <.001 |
| Prescriptions in the past year, mean ± SD | 17.02 ± 9.29 | 17.01 ± 9.21 | .991 | 17.75 ± 8.62 | 16.26 ± 9.74 | <.001 |
| Receipt of home care in past year | 574 (62.1%) | 3625 (61.3%) | .668 | 2066 (59.6%) | 2133 (63.3%) | .002 |
| Receipt of prior season’s influenza vaccine | 465 (50.3%) | 3438 (58.2%) | <.001 | 2774 (80.1%) | 1129 (33.5%) | <.001 |
| Medical comorbidities | ||||||
| Anemia | 221 (23.9%) | 1729 (29.2%) | <.001 | 1021 (29.5%) | 929 (27.6%) | .079 |
| Asthma | 260 (28.1%) | 1360 (23.0%) | <.001 | 850 (24.5%) | 770 (22.8%) | .099 |
| Cancer | 315 (34.1%) | 2289 (38.7%) | .007 | 1314 (37.9%) | 1290 (38.3%) | .776 |
| COPD | 505 (54.6%) | 3014 (51.0%) | .041 | 1842 (53.2%) | 1677 (49.7%) | .005 |
| Arrhythmia | 348 (37.6%) | 2065 (34.9%) | .111 | 1272 (36.7%) | 1141 (33.8%) | .013 |
| Ischemic heart disease | 397 (42.9%) | 2375 (40.2%) | .114 | 1428 (41.2%) | 1344 (39.9%) | .254 |
| Congestive heart failure | 480 (51.9%) | 3026 (51.2%) | .689 | 1842 (53.2%) | 1664 (49.3%) | .002 |
| Chronic kidney disease | 274 (29.6%) | 1648 (27.9%) | .272 | 1016 (29.3%) | 906 (26.9%) | .024 |
| Diabetes | 426 (46.1%) | 2480 (41.9%) | .019 | 1546 (44.6%) | 1360 (40.3%) | <.001 |
| Dementia/frailty | 258 (27.9%) | 1331 (22.5%) | <.001 | 757 (21.8%) | 832 (24.7%) | .006 |
| Immunocompromise | 154 (16.6%) | 1084 (18.3%) | .215 | 674 (19.5%) | 564 (16.7%) | .003 |
| History of transient ischemic attack or stroke | 144 (15.6%) | 709 (12.0%) | .002 | 443 (12.8%) | 410 (12.2%) | .434 |
| Any of the above comorbidities | 901 (97.4%) | 5774 (97.7%) | .628 | 3412 (98.5%) | 3263 (96.8%) | <.001 |
| Underlying cause of deatha | ||||||
| Influenza | 215 (23.2%) | 20 (0.3%) | <.001 | 107 (3.1%) | 128 (3.8%) | .002 |
| Pneumonia | 146 (15.8%) | 979 (16.6%) | 605 (17.5%) | 520 (15.4%) | ||
| COPD | 81 (8.8%) | 554 (9.4%) | 356 (10.3%) | 279 (8.3%) | ||
| Acute and other respiratory infections | 45 (4.9%) | 526 (8.9%) | 296 (8.5%) | 275 (8.2%) | ||
| Circulatory system diseases | 153 (16.5%) | 1183 (20.0%) | 686 (19.8%) | 650 (19.3%) | ||
| Cancer | 75 (8.1%) | 1046 (17.7%) | 540 (15.6%) | 581 (17.2%) |
Abbreviations: COPD, chronic obstructive pulmonary disease; N/A, not applicable; SD, standard deviation.
aSum of counts does not equal the total size of the cohort because either the underlying cause of death was not included in one of the selected categories (n = 1782) or individuals were missing underlying cause of death information either because death was not recorded in the Office of the Registrar General-Deaths (ORGD) database or an underlying cause of death was not determined (n = 32).