Table 3 Characteristics of included patients according to PCR result
Influenza-negative | Influenza-positive | A(H1N1)pdm09 | A(H3N2) | B/Yamagata lineage | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
N = 7437 | N = 2177 | N = 115 | N = 1231 | N = 646 | ||||||||||
n | % | n | % | P vs. negative | n | % | P vs. negative | n | % | P vs. negative | n | % | P vs. negative | |
Age in years, median (range) | 18.4 (0–106) | 32.8 (0–100) | 0.0001 | 5.6 (0–85) | 0.0861 | 54.5 (0–100) | 0.0001 | 26.2 (0–96) | 0.0013 | |||||
Age group | <0.0001 | <0.0001 | <0.0001 | <0.0001 | ||||||||||
0–1 y | 1371 | 18.4 | 144 | 6.6 | 14 | 12.2 | 74 | 6.0 | 37 | 5.7 | ||||
2–4 y | 1777 | 23.9 | 429 | 19.7 | 36 | 31.3 | 212 | 17.2 | 133 | 20.6 | ||||
5–17 y | 547 | 7.4 | 280 | 12.9 | 14 | 12.2 | 121 | 9.8 | 118 | 18.3 | ||||
18–49 y | 1038 | 14 | 423 | 19.4 | 28 | 24.3 | 183 | 14.9 | 168 | 26.0 | ||||
50–64 y | 557 | 7.5 | 191 | 8.8 | 9 | 7.8 | 92 | 7.5 | 73 | 11.3 | ||||
65–74 y | 608 | 8.2 | 211 | 9.7 | 5 | 4.3 | 153 | 12.4 | 45 | 7.0 | ||||
75–84 y | 933 | 12.5 | 294 | 13.5 | 8 | 7.0 | 235 | 19.1 | 38 | 5.9 | ||||
≥85 | 606 | 8.1 | 205 | 9.4 | 1 | 0.9 | 161 | 13.1 | 34 | 5.3 | ||||
Sex | <0.0001 | 0.0390 | 0.0003 | 0.0040 | ||||||||||
Male | 4276 | 57.5 | 1141 | 52.4 | 55 | 47.8 | 651 | 52.9 | 333 | 51.5 | ||||
Female | 3161 | 42.5 | 1036 | 47.6 | 60 | 52.2 | 580 | 47.1 | 313 | 48.5 | ||||
Chronic conditions | 0.0940 | 0.1600 | <0.0001 | 0.004 | ||||||||||
0 | 4572 | 61.5 | 1295 | 59.5 | 78 | 67.8 | 643 | 52.2 | 434 | 67.2 | ||||
≥1 | 2865 | 38.5 | 882 | 40.5 | 37 | 32.2 | 588 | 47.8 | 212 | 32.8 | ||||
Underlying chronic conditions | ||||||||||||||
Cardiovascular disease | 1529 | 20.6 | 469 | 21.5 | 0.3210 | 18 | 15.7 | 0.1820 | 319 | 25.9 | <0.0001 | 109 | 16.9 | 0.02200 |
Chronic obstructive pulmonary disease | 1153 | 15.5 | 306 | 14.1 | 0.0570 | 7 | 6.1 | 0.0001 | 222 | 18.0 | 0.0270 | 60 | 9.3 | <0.0001 |
Asthma | 346 | 4.7 | 100 | 4.6 | 0.9080 | 5 | 4.3 | 0.8760 | 65 | 5.3 | 0.3440 | 24 | 3.7 | 0.2600 |
Immunodeficiency/organ transplant | 92 | 1.2 | 14 | 0.6 | 0.0130 | 0 | 0.0 | 0.0920 | 8 | 0.6 | 0.0550 | 6 | 0.9 | 0.4750 |
Diabetes | 814 | 10.9 | 234 | 10.7 | 0.7960 | 8 | 7.0 | 0.1480 | 180 | 14.6 | <0.0001 | 34 | 5.3 | <0.0001 |
Renal impairment | 463 | 6.2 | 143 | 6.6 | 0.5640 | 2 | 1.7 | 0.0200 | 108 | 8.8 | 0.0010 | 27 | 4.2 | 0.0280 |
Neuromuscular disease | 215 | 2.9 | 52 | 2.4 | 0.2020 | 8 | 7.0 | 0.0290 | 19 | 1.5 | 0.0040 | 22 | 3.4 | 0.4670 |
Neoplasm | 238 | 3.2 | 63 | 2.9 | 0.4660 | 4 | 3.5 | 0.8680 | 38 | 3.1 | 0.8330 | 17 | 2.6 | 0.4160 |
Cirrhosis/liver disease | 168 | 2.3 | 34 | 1.6 | 0.0390 | 0 | 0.0 | 0.0220 | 19 | 1.5 | 0.0950 | 11 | 1.7 | 0.3390 |
Autoimmune disease | 127 | 1.7 | 48 | 2.2 | 0.1360 | 1 | 0.9 | 0.4470 | 36 | 2.9 | 0.0060 | 8 | 1.2 | 0.3510 |
Pregnant (women 15–45 y) | 138 | 33.7 | 160 | 64.8 | 0.0000 | 11 | 68.8 | 0.0050 | 64 | 55.7 | <0.0001 | 68 | 70.1 | <0.0001 |
Obese (all ages) | 1300 | 17.5 | 358 | 16.4 | 0.2590 | 15 | 13.0 | 0.1970 | 223 | 18.1 | 0.5890 | 92 | 14.2 | 0.0320 |
Smoking habits (patients ≥18 y) | ||||||||||||||
Never smoked | 1760 | 47.0 | 717 | 54.2 | 23 | 45.1 | 451 | 54.7 | 191 | 53.4 | ||||
Past smoker | 1164 | 31.1 | 380 | 28.7 | 14 | 27.5 | 252 | 30.6 | 96 | 26.8 | ||||
Current smoker | 818 | 21.9 | 227 | 17.1 | 14 | 27.5 | 121 | 14.7 | 71 | 19.8 | ||||
Functional status impairment (Barthel score; patients ≥65 y) | ||||||||||||||
Total (0–15) | 152 | 7.2 | 47 | 6.7 | 0 | 0.0 | 41 | 7.6 | 5 | 4.3 | ||||
Severe (20–35) | 76 | 3.6 | 19 | 2.7 | 0 | 0.0 | 13 | 2.4 | 4 | 3.5 | ||||
Moderate (40–55) | 140 | 6.7 | 46 | 6.6 | 0 | 0.0 | 32 | 5.9 | 11 | 9.6 | ||||
Mild (60–90) | 518 | 24.7 | 148 | 21.1 | 1 | 7.1 | 111 | 20.5 | 32 | 27.8 | ||||
Minimal (95–100) | 1214 | 57.8 | 441 | 62.9 | 13 | 92.9 | 345 | 63.7 | 63 | 54.8 | ||||
Influenza vaccination ≥14 d since onset of symptoms | 1566 | 21.1 | 447 | 20.5 | 0.5960 | 6 | 5.2 | <0.0001 | 356 | 28.9 | <0.0001 | 57 | 8.8 | <0.0001 |