title: Risk Factors Associated With Infant Deaths From Pertussis: A Case-Control Study.
abstract: BACKGROUND
  In the current era, most pertussis deaths occur in infants <3 months of age. Leukocytosis with lymphocytosis and pneumonia are commonly observed among cases of severe pertussis.
  
  
  METHODS
  Risk factors associated with fatal pertussis were identified by comparing fatal pertussis cases among patients <120 days of age occurring from 1 January 1998 through 26 December 2014, matched by age (<120 days), county of residence, and closest symptom onset date with 1-4 nonfatal hospitalized cases. California Department of Public Health surveillance data were reviewed to identify cases; demographics, clinical presentation, and course were abstracted from corresponding birth and medical records. Logistic regression and classification tree analyses were used to examine the risk of fatal pertussis with respect to identified factors.
  
  
  RESULTS
  Fifty-three fatal infant pertussis cases were identified and compared with 183 nonfatal hospitalized pertussis cases. Fatal cases had significantly lower birth weight, younger gestational age, younger age at time of cough onset, and higher peak white blood cell (WBC) and lymphocyte counts. Fatal cases were less likely to have received macrolide antibiotics and more likely to have received steroids or nitric oxide and to develop pulmonary hypertension, seizures, encephalitis, and pneumonia. Additionally, exchange transfusion, extracorporeal membrane oxygenation, and intubation occurred significantly more frequently among fatal cases. In multivariate analyses, peak WBC count, birth weight, intubation, and receipt of nitric oxide were predictors of death.
  
  
  CONCLUSIONS
  Early recognition of pertussis in young infants and treatment with appropriate antibiotic therapy are important in preventing death. Several risk factors are strongly associated with fatal pertussis in infants.
authors.affiliation: Immunization Branch, California Department of Public Health, Richmond.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Winter
authors.affiliation: Immunization Branch, California Department of Public Health, Richmond.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Zipprich
authors.affiliation: Immunization Branch, California Department of Public Health, Richmond.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Harriman
authors.affiliation: Immunization Branch, California Department of Public Health, Richmond.
authors.forename: Erin L
authors.initials: EL
authors.lastname: Murray
authors.affiliation: Statistical Biomathematical Consulting Clinic, Department of Biomathematics.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Gornbein
authors.affiliation: Immunization Branch, California Department of Public Health, Richmond.
authors.forename: Sandra Jo
authors.initials: SJ
authors.lastname: Hammer
authors.affiliation: Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles.
authors.forename: Nava
authors.initials: N
authors.lastname: Yeganeh
authors.affiliation: Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles.
authors.forename: Kristina
authors.initials: K
authors.lastname: Adachi
authors.affiliation: Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles.
authors.forename: James D
authors.initials: JD
authors.lastname: Cherry
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary; D007223:Infant; D007231:Infant, Newborn; D007964:Leukocytosis; D008218:Lymphocytosis; D008297:Male; D011014:Pneumonia; D012307:Risk Factors; D014917:Whooping Cough / Q000150:complications* / Q000453:epidemiology / Q000401:mortality*; D055815:Young Adult
keywords: infant pertussis; leukocytosis; lymphocytosis; pneumonia; pulmonary hypertension