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Table 4 Multivariable logistic regression analysis of the association between pertussis vaccination and the clinical course and treatment of pertussis, stratified for term and preterm infants (crude and adjusted OR and 95% CI)

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

  Probable and certain term infants (n = 481)a Preterm infants (n = 60)
  Unvaccinated infants (n = 268) Vaccinated infants (n = 213) crude OR (95% CI) adjusted OR (95% CI)b Unvaccinated infants (n = 23) Vaccinated infants (n = 37) crude OR (95% CI) adjusted OR (95% CI)b
Symptoms at admission
 Coughing attacks 197 (73.5%) 151 (70.9%) 0.9 (0.6–1.3) 0.8 (0.4–1.3) 17 (73.9%) 26 (70.3%) 0.8 (0.3–2.7) 0.8 (0.1–5.6)
 Apnea 47 (17.5%) 22 (10.3%) 0.5 (0.3–0.9) 0.6 (0.3–1.1) 10 (43.5%) 5 (13.5%) 0.2 (0.06–0.7) 0.2 (0.03–1.5)
 Whooping 6 (2.2%) 12 (5.6%) 2.6 (0.96–7.1) 1.8 (0.5–6.8) 1 (4.4%) 0 < 0.001 (< 0.001- > 999.9) 0.4 (< 0.001- > 999.9)
Vomiting 94 (35.1%) 79 (37.1%) 1.1 (0.8–1.6) 0.9 (0.6–1.6) 8 (34.8%) 13 (35.1%) 1.0 (0.3–3.0) 0.6 (0.1–3.3)
 prolonged inspiratory effort 15 (5.6%) 19 (8.9%) 1.7 (0.8–3.3) 1.0 (0.4–2.3) 1 (4.4%) 4 (10.8%) 2.7 (0.3–25.4) 1.6 (0.1–26.1)
 Collapse 2 (0.8%) 2 (0.9%) 1.3 (0.2–9.0) 7.2 (0.2–226.7) 1 (4.4%) 1 (2.7%) 0.6 (0.04–10.3) 0.6 (< 0.001- > 999.9)
 Cyanosis 126 (47.0%) 88 (41.3%) 0.8 (0.6–1.1)c 1.1 (0.7–1.8)c 5 (21.7%) 17 (45.9%) 3.1 (0.9–10.0)c 1.9 (0.3–11.6)c
 Fever 17 (6.3%) 21 (9.9%) 1.6 (0.8–3.1) 0.7 (0.3–1.7) 2 (8.7%) 4 (10.8%) 1.3 (0.2–7.6) > 999.9 (< 0.001- > 999.9)
 Feeding problems 87 (32.5%) 63 (29.6%) 0.9 (0.6–1.3) 0.9 (0.5–1.4) 10 (43.5%) 12 (32.4%) 0.6 (0.2–1.8) 0.8 (0.2–4.5)
Complications
 Any complication 30 (11.2%) 9 (4.2%) 0.4 (0.2–0.8) 0.9 (0.4–2.5) 5 (21.7%) 3 (8.1%) 0.3 (0.07–1.5) 0.2 (0.01–4.6)
Treatment
 Antibiotics before admission 37 (14.2%) 52 (25.1%) 1.8 (1.2–2.8) 1.2 (0.7–2.1) 2 (9.5%) 9 (24.3%) 2.7 (0.6–11.4) 12.3 (0.8–188.3)
 Antibiotics during admission 230 (87.5%) 157 (74.4%) 0.4 (0.3–0.7) 0.7 (0.4–1.3) 21 (95.5%) 32 (86.5%) 0.3 (0.03–2.8) 1.7 (0.1–23.7)
 Artificial respiration 23 (8.9%) 5 (2.4%) 0.3 (0.1–0.7) 0.8 (0.2–3.4) 7 (31.8%) 2 (5.6%) 0.1 (0.02–0.7) 0.4 (0.02–5.7)
 Additional oxygen 133 (50.4%) 33 (15.9%) 0.2 (0.1–0.3) 0.3 (0.2–0.5) 13 (59.1%) 10 (27.8%) 0.2 (0.08–0.8) 0.6 (0.09–4.0)
 Admission intensive care unit (ICU) 42 (15.7%) 5 (2.4%) 0.1 (0.05–0.3) 0.3 (0.1–1.1) 6 (26.1%) 2 (5.4%) 0.2 (0.03–0.9) 0.6 (0.04–7.6)
Discharge
 Symptoms remaining 206 (76.9%) 162 (76.1%) 0.9 (0.6–1.3) 0.7 (0.5–1.2) 14 (60.9%) 30 (81.1% 1.9 (0.7–5.1) 2.1 (0.7–6.7)
  1. Unvaccinated infants are set as reference. Significant results are in bold
  2. aterm infants in main analysis
  3. badjusted for coinfections and age in months at admission
  4. ccrude and adjusted OR for cyanosis in term and preterms are significantly different (p = 0.03 and p = 0.02, respectively)