Leukocytosis

From January 1, 2010, to June 30, 2012, adults 18 years of age or older were enrolled at three hospitals in Chicago (John H. Stroger, Jr., Hospital of Cook County, Northwestern Memorial Hospital, and Rush University Medical Center) and at two in Nashville (University of Tennessee Health Science Center–Saint Thomas Health and Vanderbilt University Medical Center). We sought to enroll all eligible adults; therefore, trained staff screened adults for enrollment at least 18 hours per day, 7 days per week. Written informed consent was obtained from all the patients or their caregivers before enrollment. The study protocol was approved by the institutional review board at each participating institution and at the CDC. Weekly teleconferences, enrollment reports, data audits, and annual study-site visits were conducted to ensure uniform procedures among the study sites. Patients or their caregivers provided demographic and epidemiologic data, and medical charts were abstracted for clinical data. All the authors vouch for the accuracy and completeness of the data and analyses reported and for the fidelity of the study to the protocol. All the authors made the decision to submit the manuscript for publication.
Adults were eligible for enrollment if they were admitted to a study hospital on the basis of a clinical assessment by the treating clinician; resided in the study catchment area (see the Supplementary Appendix, available with the full text of this article at NEJM.org); had evidence of acute infection, defined as reported fever or chills, documented fever or hypothermia, leukocytosis or leukopenia, or new altered mental status; had evidence of an acute respiratory illness, defined as new cough or sputum production, chest pain, dyspnea, tachypnea, abnormal lung examination, or respiratory failure; and had evidence consistent with pneumonia as assessed by means of chest radiography by the clinical team within 48 hours before or after admission.
Patients were excluded if they had been hospitalized recently (<28 days for immunocompetent patients and <90 days for immunosuppressed patients), had been enrolled in the EPIC study within the previous 28 days, were functionally dependent nursing home residents,^{14 (link)} or had a clear alternative diagnosis (see the Supplementary Appendix). Patients were also excluded if they had undergone tracheotomy, if they had a percutaneous endoscopic gastrostomy tube, if they had cystic fibrosis, if they had cancer with neutropenia, if they had received a solid-organ or hematopoietic stem-cell transplant within the previous 90 days, if they had active graft-versus-host disease or bronchiolitis obliterans, or if they had human immunodeficiency virus infection with a CD4 cell count of less than 200 per cubic millimeter.^{10 (link)}

From January 1, 2010 to June 30, 2012, children <18 years old were enrolled in the EPIC study at Le Bonheur Children's Hospital (Memphis, TN), Monroe Carell Jr. Children's Hospital at Vanderbilt (Nashville, TN), and Primary Children's Hospital (Salt Lake City, UT). We sought to enroll all eligible children; thus trained staff screened for enrollment for at least 18 hours each day, 7 days each week. Written informed consent was obtained before enrollment. The study protocol was approved by the institutional review boards at each institution and the CDC. Weekly study teleconferences, required weekly enrollment reports, data audits, and annual site visits were conducted to ensure uniform procedures among sites.
Children were included if they 1) were admitted to one of the three study hospitals;2) resided in one of the 22 counties in the study catchment areas;3) had evidence of acute infection defined as reported fever or chills, documented fever or hypothermia, or leukocytosis or leukopenia; 4) had evidence of an acute respiratory illness defined as new cough or sputum production, chest pain, dyspnea, tachypnea, abnormal lung examination, or respiratory failure; and 5) had chest radiography consistent with pneumonia ≤72 hours of admission.
Children were excluded if they were recently hospitalized (<7 days for immunocompetent, <90 days for immunosuppressed), enrolled in the EPIC study <28 days earlier, resided in an extended care facility, had an alternative respiratory diagnosis, or were newborns who never left the hospital. Children with the following were excluded: tracheostomy, cystic fibrosis, cancer with neutropenia, solid organ or hematopoietic stem cell transplant ≤90 days earlier, active graft-versus-host-disease or bronchiolitis obliterans, or human immunodeficiency virus infection with CD4 cell count <200 cells/mm³ (or CD4%<14%).

Gestational age was determined by the last menstrual period and was confirmed by ultrasound examination; the date derived from ultrasound was used if inconsistent with menstrual dating. Clinical chorioamnionitis was diagnosed by the presence of maternal fever (temperature > 37.8°C) accompanied by two or more of the following criteria: 1) uterine tenderness; 2) malodorous vaginal discharge; 3) fetal tachycardia (heart rate > 160 beats/min); 4) maternal tachycardia (heart rate > 100 beats/min); and 5) maternal leukocytosis (leukocyte count > 15,000 cells/mm³) [6 (link), 16 (link)]. Spontaneous term labor was defined as the presence of regular uterine contractions with a frequency of at least 1 every 10 min and cervical changes after 37 weeks of gestation.
Microbial invasion of the amniotic cavity was defined according to the results of AF culture and polymerase chain reaction with electrospray ionization mass spectrometry (PCR/ESI-MS) (Ibis® Technology – Athogen, Carlsbad, CA) [51 (link), 55 (link), 61 (link), 62 (link)]. Intra-amniotic inflammation was diagnosed when AF interleukin (IL)-6 concentration was ≥ 2.6 ng/mL [63 (link), 64 ]. Based on the results of AF cultures, PCR/ESI-MS and AF concentration of IL-6, patients were classified as having: 1) no intra-amniotic inflammation/infection (either using AF culture or PCR/ESI-MS); 2) MIAC (identification of microorganisms by either AF cultures or PCR/ESI-MS without intra-amniotic inflammation); 3) microbial-associated intra-amniotic inflammation (combination of MIAC and intra-amniotic inflammation); or 4) intra-amniotic inflammation without detectable microorganisms (an elevated AF IL-6 concentration without evidence of microorganisms using cultivation or molecular methods). Acute histologic chorioamnionitis was diagnosed based on the presence of inflammatory cells in the chorionic plate and/or chorioamniotic membranes [65 (link)], and acute funisitis was diagnosed by the presence of neutrophils in the wall of the umbilical vessels and/or Wharton’s jelly, using criteria previously described [65 (link), 66 (link)].