Table 2. Hospitalised Bordetella pertussis cases aged < 1 year by age group, sex, laboratory components, clinical presentation, most likely source of infection and severity criteria, PERTINENT study, Europe, 1 December 2015–31 December 2018 (n = 469 cases).
| Characteristic | Cases (all < 1 year old) (n = 469) |
Cases 0–3 months old (n = 354) |
Cases 4–11 months old (n = 115) |
p value | ||||
|---|---|---|---|---|---|---|---|---|
| Number | % | Number | % | Number | % | |||
| Demographic | ||||||||
| Sex (n = 469) | Female | 222 | 47.3 | 165 | 46.6 | 57 | 49.6 | 0.593 |
| Male | 247 | 52.7 | 189 | 53.4 | 58 | 50.4 | ||
| Laboratory components | ||||||||
| Nasopharyngeal specimen collection (n = 448) | Aspirate only | 346 | 77.2 | 252 | 75.4 | 94 | 82.5 | 0.321 |
| Swab only | 80 | 17.9 | 64 | 19.2 | 16 | 14.0 | ||
| Both | 22 | 4.9 | 18 | 5.4 | 4 | 3.5 | ||
| PCR (n = 465) | Positive | 465 | 100.0 | 351 | 100.0 | 114 | 100.0 | NA |
| Negative | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | ||
| Culture (n = 211)a | Positive | 108 | 51.2 | 89 | 51.7 | 19 | 48.7 | 0.859 |
| Negative | 103 | 48.8 | 83 | 48.3 | 20 | 51.3 | ||
| Clinical presentation | ||||||||
| Cough (n = 469) | Yes | 456 | 97.2 | 342 | 96.6 | 114 | 99.1 | 0.202 |
| No | 13 | 2.8 | 12 | 3.4 | 1 | 0.9 | ||
| Cough with paroxysms (n = 456) | Yes | 393 | 86.2 | 298 | 87.1 | 95 | 83.3 | 0.347 |
| No | 63 | 13.8 | 44 | 12.9 | 19 | 16.7 | ||
| Whooping cough (n = 269) | Yes | 122 | 45.4 | 91 | 47.2 | 31 | 40.8 | 0.415 |
| No | 147 | 54.6 | 102 | 52.8 | 45 | 59.2 | ||
| Post-tussive vomiting (n = 449) | Yes | 219 | 48.8 | 164 | 48.7 | 55 | 49.1 | 1.000 |
| No | 230 | 51.2 | 173 | 51.3 | 57 | 50.9 | ||
| Apnoea (n = 466) | Yes | 235 | 50.4 | 193 | 55.0 | 42 | 36.5 | 0.001 |
| No | 231 | 49.6 | 158 | 45.0 | 73 | 63.5 | ||
| Cyanosis (n = 467) | Yes | 239 | 51.2 | 192 | 54.5 | 47 | 40.9 | 0.013 |
| No | 228 | 48.8 | 160 | 45.5 | 68 | 59.1 | ||
| Epidemiological link (n = 457) | Yes | 167 | 36.5 | 124 | 35.8 | 43 | 38.7 | 0.651 |
| No | 290 | 63.5 | 222 | 64.2 | 68 | 61.3 | ||
| Diagnosis by a clinician (n = 469) | Yes | 368 | 78.5 | 275 | 77.7 | 93 | 80.9 | 0.516 |
| No | 101 | 21.5 | 79 | 22.3 | 22 | 19.1 | ||
| Reported source of infection | ||||||||
| Mother (n = 424) | Yes | 106 | 25.0 | 88 | 27.5 | 18 | 17.3 | 0.038 |
| No | 318 | 75.0 | 232 | 72.5 | 86 | 82.7 | ||
| Father (n = 419) | Yes | 82 | 19.6 | 66 | 21.0 | 16 | 15.4 | 0.255 |
| No | 337 | 80.4 | 249 | 79.0 | 88 | 84.6 | ||
| Sibling (n = 416) | Yes | 128 | 30.8 | 102 | 32.8 | 26 | 24.8 | 0.143 |
| No | 288 | 69.2 | 209 | 67.2 | 79 | 75.2 | ||
| Grandparents (n = 409) | Yes | 41 | 10.0 | 33 | 10.8 | 8 | 7.7 | 0.451 |
| No | 368 | 90.0 | 272 | 89.2 | 96 | 92.3 | ||
| Caregiver (n = 240) | Yes | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | NA |
| No | 240 | 100.0 | 175 | 100.0 | 65 | 100.0 | ||
| Severity criteria | ||||||||
| Death (n = 466) | Yes | 5 | 1.1 | 5 | 1.4 | 0 | 0.0 | 0.340 |
| No | 461 | 98.9 | 346 | 98.6 | 115 | 100.0 | ||
| ICU (n = 330) | Yes | 83 | 25.2 | 80 | 31.5 | 3 | 3.9 | 0.000 |
| No | 247 | 74.8 | 174 | 68.5 | 73 | 96.1 | ||
| ECMO (n = 336) | Yes | 7 | 2.1 | 7 | 2.7 | 0 | 0.0 | 0.360 |
| No | 329 | 97.9 | 251 | 97.3 | 78 | 100.0 | ||
| Pneumonia (n = 327) | Yes | 14 | 4.3 | 12 | 4.8 | 2 | 2.7 | 0.745 |
| No | 313 | 95.7 | 240 | 95.2 | 73 | 97.3 | ||
| Encephalopathy (n = 327) | Yes | 3 | 0.9 | 3 | 1.2 | 0 | 0.0 | 1.000 |
| No | 324 | 99.1 | 249 | 98.8 | 75 | 100.0 | ||
| Seizure (n = 328) | Yes | 10 | 3.0 | 8 | 3.2 | 2 | 2.7 | 1.000 |
| No | 318 | 97.0 | 245 | 96.8 | 73 | 97.3 | ||
| Eating difficulties (n = 269) | Yes | 62 | 23.0 | 50 | 25.4 | 12 | 16.7 | 0.144 |
| No | 207 | 77.0 | 147 | 74.6 | 60 | 83.3 | ||
| Kidney failure (n = 267) | Yes | 4 | 1.5 | 4 | 2.0 | 0 | 0.0 | 0.576 |
| No | 263 | 98.5 | 192 | 98.0 | 71 | 100.0 | ||
| Dehydration (n = 300) | Yes | 12 | 4.0 | 11 | 4.8 | 1 | 1.4 | 0.305 |
| No | 288 | 96.0 | 216 | 95.2 | 72 | 98.6 | ||
ECMO: Extracorporeal membrane oxygenation; ICU: intensive care unit; PERTINENT: Pertussis in Infants European Network.
a Cultures were done for 255 cases, but the results were only available for 211 cases.
Number of cases presented for the different characteristics are those with information available.