| Characteristic | Immunity, no. | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | |||
|---|---|---|---|---|---|---|---|---|
| TP | FP | FN | TN | |||||
| Total | 9303 | 1218 | 9395 | 27 385 | 49.8 (49.0-50.5) | 95.7 (95.5-96.0) | 88.4 (87.8-89.0) | 74.5 (74.0-74.9) |
| Canadian Community Health Survey cycle | ||||||||
| 2007/08 | 6506 | 1023 | 6666 | 19 645 | 49.4 (48.5-50.2) | 95.1 (94.8-95.3) | 86.4 (85.6-87.2) | 74.7 (74.1-75.2) |
| 2009/10 | 2797 | 195 | 2729 | 7740 | 50.6 (49.3-51.9) | 97.5 (97.2-97.9) | 93.5 (92.6-94.4) | 73.9 (73.1-74.8) |
| Age group, yr | ||||||||
| 12-17 | 205 | 71 | 803 | 2992 | 20.3 (17.9-22.8) | 97.7 (97.1-98.2) | 74.3 (69.1-79.4) | 78.8 (77.5-80.1) |
| 18-49 | 1510 | 275 | 3272 | 15 190 | 31.6 (30.3-32.9) | 98.2 (98.0-98.4) | 84.6 (82.9-86.3) | 82.3 (81.7-82.8) |
| 50-64 | 2319 | 263 | 2947 | 6285 | 44.0 (42.7-45.4) | 96.0 (95.5-96.5) | 89.8 (88.6-91.0) | 68.1 (67.1-69.0) |
| ≥ 65 | 5269 | 609 | 2373 | 2918 | 68.9 (67.9-70.0) | 82.7 (81.5-84.0) | 89.6 (88.9-90.4) | 55.2 (53.8-56.5) |
| Sex | ||||||||
| Female | 5536 | 708 | 5448 | 14 211 | 50.4 (49.5-51.3) | 95.3 (94.9-95.6) | 88.7 (87.9-89.4) | 72.3 (71.7-72.9) |
| Male | 3767 | 510 | 3947 | 13 174 | 48.8 (47.7-49.9) | 96.3 (96.0-96.6) | 88.1 (87.1-89.0) | 76.9 (76.3-77.6) |
| Residence | ||||||||
| Urban | 7474 | 1016 | 7229 | 21 687 | 50.8 (50.0-51.6) | 95.5 (95.3-95.8) | 88.0 (87.3-88.7) | 75.0 (74.5-75.5) |
| Rural | 1812 | 201 | 2152 | 5638 | 45.7 (44.2-47.3) | 96.6 (96.1-97.0) | 90.0 (88.7-91.3) | 72.4 (71.4-73.4) |
| Has a regular doctor (patient age, yr) | ||||||||
| Yes (< 65) | 3924 | 585 | 6430 | 21 505 | 37.9 (37.0-38.8) | 97.4 (97.1-97.6) | 87.0 (86.0-88.0) | 77.0 (76.5-77.5) |
| Yes (≥ 65) | 5205 | 600 | 2229 | 2632 | 70.0 (69.0-71.1) | 81.4 (80.1-82.8) | 89.7 (88.9-90.4) | 54.1 (52.7-55.5) |
| No (< 65) | 110 | 24 | 592 | 2962 | 15.7 (13.0-18.4) | 99.2 (98.9-99.5) | 82.1 (75.6-88.6) | 83.3 (82.1-84.6) |
| No (≥ 65) | 64 | 9 | 144 | 286 | 30.8 (24.5-37.0) | 96.9 (95.0-98.9) | 87.7 (80.1-95.2) | 66.5 (62.1-71.0) |
| Risk factors for serious influenza infections (age ≥ 65 yr) | ||||||||
| Hypertension | 4012 | 448 | 1589 | 1671 | 71.6 (70.4-72.8) | 78.9 (77.1-80.6) | 90.0 (89.1-90.8) | 51.3 (49.5-53.0) |
| Asthma | 651 | 63 | 270 | 244 | 70.7 (67.7-73.6) | 79.5 (75.0-84.0) | 91.2 (89.1-93.3) | 47.5 (43.2-51.8) |
| Diabetes | 1 40 | 159 | 544 | 554 | 71.1 (69.1-73.2) | 77.7 (74.6-80.8) | 89.4 (87.8-91.0) | 50.5 (47.5-53.4) |
| Cancer | 858 | 81 | 342 | 359 | 71.5 (68.9-74.1) | 81.6 (78.0-85.2) | 91.4 (89.6-93.2) | 51.2 (47.5-54.9) |
| COPD | 586 | 55 | 265 | 234 | 68.9 (65.7-72.0) | 81.0 (76.4-85.5) | 91.4 (89.3-93.6) | 46.9 (42.5-51.3) |
| Congestive heart failure | 571 | 51 | 202 | 178 | 73.9 (70.8-77.0) | 77.7 (72.3-83.1) | 91.8 (89.6-94.0) | 46.8 (41.8-51.9) |
| Myocardial infarction | 329 | 34 | 130 | 120 | 71.7 (67.6-75.8) | 77.9 (71.4-84.5) | 90.6 (87.6-93.6) | 48.0 (41.8-54.2) |
| Chronic kidney disease | 323 | 36 | 134 | 116 | 70.7 (66.5-74.9) | 76.3 (69.6-83.1) | 90.0 (86.9-93.1) | 46.4 (40.2-52.6) |
| Morbid obesity* | 67 | < 6 | < 30 | 45 | 72.0 (62.9-81.2) | 90.0 (81.7-98.3) | 93.1 (87.2-98.9) | 63.4 (52.2-74.6) |
| Stroke | 334 | 39 | 124 | 137 | 72.9 (68.9-77.0) | 77.8 (71.7-84.0) | 89.5 (86.4-92.6) | 52.5 (46.4-58.5) |
| Immunosuppression | 337 | 25 | 133 | 123 | 71.7 (67.6-75.8) | 83.1 (77.1-89.1) | 93.1 (90.5-95.7) | 48.0 (41.9-54.2) |
| Dementia | 107 | 21 | 37 | 59 | 74.3 (67.2-81.4) | 73.8 (64.1-83.4) | 83.6 (77.2-90.0) | 61.5 (51.7-71.2) |
| No risk factors | 733 | 95 | 478 | 856 | 60.5 (57.8-63.3) | 90.0 (88.1-91.9) | 88.5 (86.4-90.7) | 64.2 (61.6-66.7) |
| Risk factors for serious influenza infections (age < 65 yr) | ||||||||
| Hypertension | 1460 | 176 | 1471 | 2999 | 49.8 (48.0-51.6) | 94.5 (93.7-95.3) | 89.2 (87.7-90.7) | 67.1 (65.7-68.5) |
| Asthma | 734 | 87 | 1084 | 3092 | 40.4 (38.1-42.6) | 97.3 (96.7-97.8) | 89.4 (87.3-91.5) | 74.0 (72.7-75.4) |
| Diabetes | 649 | 76 | 572 | 983 | 53.2 (50.4-56.0) | 92.8 (91.3-94.4) | 89.5 (87.3-91.7) | 63.2 (60.8-65.6) |
| Cancer | 215 | 19 | 243 | 459 | 46.9 (42.4-51.5) | 96.0 (94.3-97.8) | 91.9 (88.4-95.4) | 65.4 (61.9-68.9) |
| COPD | 152 | 21 | 122 | 161 | 55.5 (49.6-61.4) | 88.5 (83.8-93.1) | 87.9 (83.0-92.7) | 56.9 (51.1-62.7) |
| Congestive heart failure | 81 | 11 | 60 | 81 | 57.4 (49.3-65.6) | 88.0 (81.4-94.7) | 88.0 (81.4-94.7) | 57.4 (49.3-65.6) |
| Myocardial infarction | 94 | 10 | 93 | 118 | 50.3 (43.1-57.4) | 92.2 (87.5-96.8) | 90.4 (84.7-96.1) | 55.9 (49.2-62.6) |
| Chronic kidney disease | 81 | < 6 | < 75 | 120 | 52.9 (45.0-60.9) | 96.8 (93.7-99.9) | 95.3 (90.9-99.8) | 62.5 (55.7-69.3) |
| Morbid obesity* | 144 | 27 | 141 | 411 | 50.5 (44.7-56.3) | 93.8 (91.6-96.1) | 84.2 (78.7-89.7) | 74.5 (70.8-78.1) |
| Stroke | 63 | < 6 | < 50 | 113 | 57.3 (48.0-66.5) | 96.6 (93.3-99.9) | 94.0 (88.4-99.7) | 70.6 (63.6-77.7) |
| Pregnancy† | 67 | 13 | 93 | 565 | 41.9 (34.2-49.5) | 97.8 (96.5-99.0) | 83.8 (75.7-91.8) | 85.9 (83.2-88.5) |
| No risk factors | 1725 | 321 | 4209 | 17 447 | 29.1 (27.9-30.2) | 98.2 (98.0-98.4) | 84.3 (82.7-85.9) | 80.6 (80.0-81.1) |
Note: CI = confidence interval, COPD = chronic obstructive pulmonary disease, FN = false negative, FP = false positive, NPV = negative predictive value, PPV = positive predictive value, TN = true negative, TP = true positive.
*Body mass index > 40.
†Date of delivery between Nov. 1 and June 1.