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Table 1 Clinical course, diagnostic tests, and treatment of pertussis in term and preterm infants. Denominator is the number of infants in the group, which is noted in column headings or the respective cells

From: Pertussis hospitalizations among term and preterm infants: clinical course and vaccine effectiveness

  Total group (n = 676) Probable and certain term infants (n = 596)a Certain term infants (n = 388)b Preterm infants (n = 80)
Characteristics of hospitalization, clinical course, and treatment
 Boys; n (%)1 335 (49.6%) 295 (49.5%) 185 (47.7%) 40 (50%)
 Age in months at admittance; median (range) 2.0 (0–36) 2.0 (0–35) 2.0 (0–35) 3.0 (0–25)c,d
 Duration of hospitalization in days; median (range) 5.0 (1–51) 5.0 (1–51) 5.0 (1–51) 6.0 (1–49)
 Admission intensive care unit (ICU); n (%) 69 (10.2%) 59 (9.9%) 50 (12.9%) 10 (12.5%)
 Duration ICU stay in days; median (range) 9 (2–34) 9 (2–25) 9 (2–25) 15 (8–34)c,d
 Vaccinated at admission; n (%) 250/541 (46.2%) 213/481 (44.3%) 130/319 (40.7%) 37/60 (61.7%)c,d
 Coughing attacks; n (%) 494 (73.1%) 438 (73.5%) 280 (72.2%) 56 (70.0%)
 Apnea; n (%) 110 (16.3%) 92 (15.4%) 71 (18.3%) 18 (22.5%)
 Whooping; n (%) 24 (3.6%) 23 (3.9%) 18 (4.6%) 1 (1.3%)
 Vomiting; n (%) 238 (35.2%) 210 (35.2%) 146 (37.6%) 28 (35.0%)
 Prolonged inspiratory effort; n (%) 49 (7.3%) 42 (7.1%) 33 (8.5%) 7 (8.8%)
 Collapse; n (%) 8 (1.2%) 6 (1.0%) 5 (1.3%) 2 (2.5%)
 Cyanosis; n (%) 284 (42.0%) 259 (43.5%) 176 (45.4%) 25 (31.3%)c,d
 Fever; n (%) 60 (8.9%) 52 (8.7%) 33 (8.5%) 8 (10.0%)
 Feeding problems; n (%) 212 (31.4%) 185 (31.0%) 133 (34.3%) 27 (33.8%)
 Any complicatione; n (%) 63 (9.3%) 53 (8.9%) 39 (10.1%) 10 (12.5%)
 Antibiotics before admissionf; n (%) 131/657 (19.9%) 114/580 (19.7%) 66/377 (17.5%) 18/77 (23.4%)
 Antibiotics during admissiong; n (%) 543/674 (80.5%) 475/587 (80.9%) 313/382 (81.9%) 68/78 (87.2%)
 Intravenous antibiotics during admission; n (%) 12/403 (3.0%) 9/357 (2.5%) 6/244 (2.5%) 3/46 (6.5%)
 Antibiotic use in days; median (range) 6 (0–28) 6 (0–28) 5 (0–28) 5.5 (1–18)
 Artificial respiration; n (%) 50/654 (7.7%) 39/577 (6.8%) 32/375 (8.5%) 11/77 (14.3%)c
 Additional oxygen; n (%) 226/661 (34.2%) 198/585 (33.9%) 150/382 (39.3%) 28 (36.8%)
 Symptoms remaining; n (%) 518 (76.6%) 460 (77.2%) 298 (76.8%) 58 (72.5%)
 Re-admittance <6w after discharge; n (%) 94 (14.0%) 85 (14.3%) 56 (14.4%) 9 (11.4%)
Diagnostics
 Pertussis test: culture, PCR and serology; n (%) 34 (5.0%) 31 (5.2%) 24 (6.2%) 3 (3.8%)
 Pertussis test: culture and PCR; n (%) 59 (8.7%) 52 (8.7%) 40 (10.3%) 7 (8.8%)
 Pertussis test: PCR and serology; n (%) 84 (12.4%) 73 (12.2%) 41 (10.6%) 11 (13.8%)
 Pertussis test: culture and serology; n (%) 24 (3.6%) 24 (4.0%) 17 (4.4%) 0 (0%)
 Pertussis test: culture; n (%) 37 (5.5%) 29 (4.9%) 18 (4.6%) 8 (10%)
 Pertussis test: PCR; n (%) 329 (48.7%) 290 (48.7%) 194 (50%) 39 (48.8%)
 Pertussis test: serology; n (%) 69 (10.2%) 61 (10.2%) 36 (9.3%) 8 (10%)
 Unknown diagnostic test for pertussis; n (%) 40 (5.9%) 36 (6.0%) 18 (4.6%) 4 (5%)
 Result white blood cell counting; n (%) 225/476 (47.3%) 200/421 (47%) 141/276 (51.1%) 25/55 (45%)
 White blood cell count; median (range) 17.2 (4.3–106.1) 17.7 (5.3–106.1) 17.2 (5.3–74.3) 13.5 (4.3–64.0)
 Result C-reactive protein; n (%) 142/392 (36.2%) 119/344 (35%) 81/231 (35.1%) 23/48 (48%)
 C-reactive protein; median (range) 5 (0–415) 4.7 (0–415) 5 (0–415) 15 (0–363)c,d
 Positive co-infectionsh; n (%) 81/355 (22.8%) 63/306 (20.6%) 46/208 (22.1%) 18/49 (36.7%)c,d
Specification of prescribed antibiotics before admission
 Amoxicillin 49/132 (37%) 38/114 (33%) 23/66 (35%) 11/18 (65%)
 Azithromycin 24/132 (18%) 21/114 (18%) 17/66 (26%) 3/18 (18%)
 Ceftriaxone 1/132 (1%) 1/114 (1%) 1/66 (2%) 0/0
 Clarithromycin 41/132 (31%) 38/114 (33%) 17/66 (26%) 3/18 (18%)
 Erythromycin 7/132 (5%) 6/114 (5%) 2/66 (3%) 1/18 (6%)
 Feneticillin 1/132 (1%) 1/114 (1%) 1/66 (2%) 0/0
 Trimethoprim 1/132 (1%) 1/114 (1%) 1/66 (2%) 0/0
 unknown 7/132 (5%) 8/114 (7%) 4/66 (6%) 0/18 (0%)
Specification of prescribed antibiotics during admission
 Amoxicillin 11/543 (2%) 10/475 (2%) 7/313 (2%) 1/68 (1%)
 Azithromycin 170/543 (31%) 146/475 (31%) 98/313 (31%) 24/68 (35%)
 Cephotaxim 1/543 (0.2%) 0/0 0/0 1/68 (1%)
 Clarithromycin 314/543 (58%) 280/475 (59%) 184/313 (59%) 34/68 (50%)
 Erythromycin 44/543 (8%) 37/475 (8%) 23/313 (7%) 7/68 (10%)
 unknown 3/543 (0.6%) 2/475 (0.4%) 1/313 (0.3%) 1/68 (1%)
Specification of reported complications
 conjunctivitis 5 (0.7%) 5 (0.8%) 1 (0.3%) 0 (0%)
 convulsion 5 (0.7%) 5 (0.8%) 4 (1.0%) 0 (0%)
 encephalopathy 1 (0.2%) 1 (0.2%) 1 (0.3%) 0 (0%)
 pneumonia 11 (1.6%) 9 (1.5%) 7 (1.8%) 2 (2.5%)
 otitis media 1 (0.2%) 1 (0.2%) 0 (0%) 0 (0%)
 death 2 (0.3%) 2 (0.3%) 2 (0.5%) 0 (0%)
 bradycardia 8 (1.2%) 7 (1.2%) 6 (1.6%) 1 (1.3%)
 cardio-respiratory insufficiency 7 (1.0%) 5 (0.8%) 4 (1.0%) 2 (2.5%)
 desaturation 20 (3.0%) 18 (3.0%) 14 (3.6%) 2 (2.5%)
 feeding problems 5 (0.7%) 2 (0.3%) 0 (0%) 3 (3.8%)
 weight loss 12 (1.8%) 11 (1.9%) 8 (2.1%) 1 (1.3%)
 dehydration 1 (0.2%) 1 (0.2%) 1 (0.3%) 0 (0%)
 need for drip-feed 4 (0.6%) 2 (0.3%) 1 (0.3%) 2 (2.5%)
 gastroenteritis 3 (0.4%) 2 (0.3%) 2 (0.5%) 1 (1.3%)
 sepsis 1 (0.2%) 1 (0.2%) 0 (0%) 0 (0%)
 extreme high white blood cell count 2 (0.3%) 1 (0.2%) 0 (0%) 1 (1.3%)
 metabolic alkalosis 1 (0.2%) 1 (0.2%) 0 (0%) 0 (0%)
 hypotonia 2 (0.3%) 1 (0.2%) 1 (0.3%) 1 (1.3%)
  1. aterm infants in main analysis
  2. bterm infants in sensitivity analysis
  3. csignificant difference (p < 0.05) between certain+probable terms and preterms (main analysis)
  4. dsignificant difference (p < 0.05) between certain terms and preterms (sensitivity analysis)
  5. eSpecific complications are listed at the end of the table
  6. fSpecification of prescribed antibiotics before admission are listed at the end of the table
  7. gSpecification of prescribed antibiotics during admission are listed at the end of the table
  8. hSpecification of diagnostics for coinfections are listed in Table 2