TABLE 2

Selected Laboratory Abnormalities Closest to PICU Admission in Patients With pH1N1 and Their Association With Mortality

Laboratory Abnormalityn/N (%)RR (95% CI)
Leukocytopenia (white cell count < 5000 per μL)161/753 (21.4)1.8 (1.2–2.9)a
Leukocytosis (white cell count > 11 000 per μL)b289/753 (38.4)0.7 (0.4–1.1)
Lymphocytopenia (<1000 per μL)365/719 (50.8)1.3 (0.8–2.1)
Neutropenia (<500 per μL)33/630 (5.2)2.8 (1.5–5.5)c
Thrombocytopenia (platelet count < 150 000 per μL)190/748 (25.4)2.9 (1.8–4.4)d
Elevated creatinine levele150/739 (20.3)1.8 (1.2–2.9)f
Elevated total bilirubin level (>1.2 mg/dL [21 μmol/L])b44/447 (9.8)0.5 (0.2–1.5)
Suspected rhabdomyolysis (CPK > 200 U/L)b51/115 (44.4)1.4 (0.6–3.7)
Severe hypoxiag
    Pao2/Fio2 < 100115/239 (48.1)3 (1.6–5.8)h
    Pao2/Fio2 = 100–19965/239 (27.2)1.1 (0.4–3.4)
  • Laboratory values are based on work by Custer and Rau53 except for rhabdomyolysis. CPK indicates creatine phosphokinase; Fio2, fraction of inspired oxygen.

  • a P = .009.

  • b Newborns who were younger than 28 days were excluded from these analyses.

  • c P = .003.

  • d P < .0001.

  • e Elevated creatinine level was defined as: >1 mg/dL for newborns younger than 28 days and for adolescents aged 13 to 20 years; >0.7 mg/dL for infants aged 29 to 364 days and for children aged 1 to 12 years.

  • f P = .01.

  • g Pao2 from arterial blood gas (when available) divided by delivered concentration of Fio2; the reference-group patients' Pao2/Fio2 was ≥200.

  • h P = .0002.