| Characteristic | Immunity, no. | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | |||
|---|---|---|---|---|---|---|---|---|
| TP | FP | FN | TN | |||||
| Total | 5639 | 408 | 5744 | 16 017 | 49.5 (48.6-50.5) | 97.5 (97.3-97.8) | 93.2 (92.6-93.9) | 73.6 (73.0-74.2) |
| Canadian Community Health Survey cycle | ||||||||
| 2007/08 | 3745 | 276 | 3831 | 10 414 | 49.4 (48.3-50.6) | 97.4 (97.1-97.7) | 93.1 (92.4-93.9) | 73.1 (72.4-73.8) |
| 2009/10 | 1894 | 132 | 1913 | 5603 | 49.8 (48.2-51.3) | 97.7 (97.3-98.1) | 93.5 (92.4-94.6) | 74.5 (73.6-75.5) |
| Age group, yr | ||||||||
| 12-17 | 126 | 34 | 507 | 1745 | 19.9 (16.8-23.0) | 98.1 (97.5-98.7) | 78.8 (72.4-85.1) | 77.5 (75.8-79.2) |
| 18-49 | 960 | 112 | 2025 | 9060 | 32.2 (30.5-33.8) | 98.8 (98.6-99.0) | 89.6 (87.7-91.4) | 81.7 (81.0-82.5) |
| 50-64 | 1401 | 83 | 1770 | 3610 | 44.2 (42.5-45.9) | 97.8 (97.3-98.2) | 94.4 (93.2-95.6) | 67.1 (65.8-68.4) |
| ≥ 65 | 3152 | 179 | 1442 | 1602 | 68.6 (67.3-70.0) | 89.9 (88.6-91.3) | 94.6 (93.9-95.4) | 52.6 (50.9-54.4) |
| Sex | ||||||||
| Female | 3345 | 221 | 3320 | 8226 | 50.2 (49.0-51.4) | 97.4 (97.0-97.7) | 93.8 (93.0-94.6) | 71.2 (70.4-72.1) |
| Male | 2294 | 187 | 2424 | 7791 | 48.6 (47.2-50.0) | 97.7 (97.3-98.0) | 92.5 (91.4-93.5) | 76.3 (75.4-77.1) |
| Residence | ||||||||
| Urban | 4485 | 348 | 4360 | 12 628 | 50.7 (49.7-51.7) | 97.3 (97.0-97.6) | 92.8 (92.1-93.5) | 74.3 (73.7-75.0) |
| Rural | 1142 | 59 | 1376 | 3 357 | 45.4 (43.4-47.3) | 98.3 (97.8-98.7) | 95.1 (93.9-96.3) | 70.9 (69.6-72.2) |
| Has a regular doctor (patient age, yr) | ||||||||
| Yes (< 65) | 2424 | 218 | 3941 | 12 705 | 38.1 (36.9-39.3) | 98.3 (98.1-98.5) | 91.7 (90.7-92.8) | 76.3 (75.7-77.0) |
| Yes (≥ 65) | 3119 | 176 | 1349 | 1441 | 69.8 (68.5-71.2) | 89.1 (87.6-90.6) | 94.7 (93.9-95.4) | 51.6 (49.8-53.5) |
| No (< 65) | 63 | 11 | 361 | 1710 | 14.9 (11.5-18.2) | 99.4 (99.0-99.7) | 85.1 (77.0-93.2) | 82.6 (80.9-84.2) |
| No (≥ 65) | 33 | < 6 | < 95 | 161 | 26.2 (18.5-33.9) | 98.2 (96.1-100.0) | 91.7 (82.6-100.0) | 63.4 (57.5-69.3) |
| Risk factors for serious influenza infections (age ≥ 65 yr) | ||||||||
| Hypertension | 2403 | 121 | 977 | 896 | 71.0 (69.6-72.6) | 88.1 (86.1-90.1) | 95.2 (94.4-96.0) | 47.8 (45.6-50.1) |
| Asthma | 368 | 18 | 159 | 134 | 69.8 (65.9-73.7) | 88.2 (83.0-93.3) | 95.3 (93.2-97.4) | 45.7 (40.0-51.4) |
| Diabetes | 808 | 52 | 332 | 293 | 70.9 (68.2-73.5) | 84.9 (81.2-88.7) | 94.0 (92.4-95.5) | 46.9 (43.0-50.8) |
| Cancer | 494 | 19 | 196 | 186 | 71.6 (68.2-75.0) | 90.7 (86.8-94.7) | 96.3 (94.7-97.9) | 48.7 (43.7-53.7) |
| COPD | 348 | 11 | 164 | 128 | 68.0 (63.9-72.0) | 92.1 (87.6-96.6) | 96.9 (95.2-98.7) | 43.8 (38.1-49.5) |
| Congestive heart failure | 345 | 10 | 117 | 94 | 74.7 (70.7-78.6) | 90.4 (84.7-96.1) | 97.2 (95.5-98.9) | 44.5 (37.8-51.3) |
| Myocardial infarction | 204 | 12 | 78 | 66 | 72.3 (67.1-77.6) | 84.6 (76.6-92.6) | 94.4 (91.4-97.5) | 45.8 (37.7-54.0) |
| Chronic kidney disease | 187 | 10 | 81 | 69 | 69.8 (64.3-75.3) | 87.3 (80.0-94.7) | 94.9 (91.9-98.0) | 46.0 (38.0-54.0) |
| Morbid obesity* | 40 | 0 | 13 | 26 | 75.5 (63.9-87.1) | 100.0 (100.0-100.0) | 100.0 (100.0-100.0) | 66.7 (51.9-81.5) |
| Stroke | 191 | 14 | 79 | 70 | 70.7 (65.3-76.2) | 83.3 (75.4-91.3) | 93.2 (89.7-96.6) | 47.0 (39.0-55.0) |
| Immunosuppression | 194 | 7 | 84 | 63 | 69.8 (64.4-75.2) | 90.0 (83.0-97.0) | 96.5 (94.0-99.0) | 42.9 (34.9-50.9) |
| Dementia | 59 | 11 | 19 | 31 | 75.6 (66.1-85.2) | 73.8 (60.5-87.1) | 84.3 (75.8-92.8) | 62.0 (48.5-75.5) |
| No risk factors | 415 | 35 | 276 | 473 | 60.1 (56.4-63.7) | 93.1 (90.9-95.3) | 92.2 (89.7-94.7) | 63.2 (59.7-66.6) |
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.