title: Burden of Influenza-Related Hospitalizations and Attributable Mortality in Pediatric Acute Lymphoblastic Leukemia.
abstract: BACKGROUND
  Influenza can be severe in patients with underlying malignancy; however, the rate of influenza hospitalizations and attributable mortality in children with cancer is unknown.
  
  
  METHODS
  We performed a retrospective cohort study among 10 698 children with new-onset acute lymphoblastic leukemia (ALL) from 41 US children's hospitals between January 1999 and September 2011. Influenza-related hospitalizations were identified using ICD-9 discharge diagnosis codes, excluding hospitalizations during low-prevalence influenza periods. Follow-up was censored at the earliest of 5 events: end of study period, expected end of chemotherapy, last known hospitalization, hematopoietic stem cell transplant, or death. Data were collected on hospitalization characteristics and resource utilization. Hospitalization rates were calculated using season-adjusted person-time. Crude attributable in-hospital mortality was calculated using baseline mortality for noninfluenza hospitalizations during the same period. Subgroup analysis was performed by time from ALL diagnosis and by age category.
  
  
  RESULTS
  The rate of influenza-related hospitalizations was 618.3 per 100 000 person-months. Rates were similar by time from ALL diagnosis and across age categories. Overall attributable in-hospital mortality was 1.0% (95% confidence interval [CI], 0.3%-2.3%) and was highest for children <6 months from diagnosis (1.6%; 95% CI, 0.4%-4.5%) and children <2 years of age (6.7%; 95% CI, 1.3%-22.7%). Total length of stay, days of broad-spectrum antibiotic exposure, and duration of intensive care were significantly greater for influenza-related hospitalizations compared with noninfluenza hospitalizations.
  
  
  CONCLUSIONS
  The burden of influenza-related hospitalizations in children with ALL is high and associated with significantly increased resource utilization and attributable mortality.
authors.affiliation: Division of Infectious Diseases Department of Pediatrics.
authors.forename: Grace E
authors.initials: GE
authors.lastname: Lee
authors.affiliation: Division of Infectious Diseases Center for Pediatric Clinical Effectiveness, The Children's Hospital of Philadelphia, Pennsylvania Department of Pediatrics Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Fisher
authors.affiliation: Center for Pediatric Clinical Effectiveness, The Children's Hospital of Philadelphia, Pennsylvania Department of Pediatrics Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia.
authors.forename: Rui
authors.initials: R
authors.lastname: Xiao
authors.affiliation: Division of Infectious Diseases Center for Pediatric Clinical Effectiveness, The Children's Hospital of Philadelphia, Pennsylvania Department of Pediatrics.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Coffin
authors.affiliation: Division of Infectious Diseases Center for Pediatric Clinical Effectiveness, The Children's Hospital of Philadelphia, Pennsylvania Department of Pediatrics.
authors.forename: Kristen
authors.initials: K
authors.lastname: Feemster
authors.affiliation: Oncology Department of Pediatrics.
authors.forename: Alix E
authors.initials: AE
authors.lastname: Seif
authors.affiliation: Oncology Department of Pediatrics.
authors.forename: Rochelle
authors.initials: R
authors.lastname: Bagatell
authors.affiliation: Oncology Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia.
authors.forename: Yimei
authors.initials: Y
authors.lastname: Li
authors.affiliation: Center for Pediatric Clinical Effectiveness, The Children's Hospital of Philadelphia, Pennsylvania.
authors.forename: Yuan-Shung V
authors.initials: YS
authors.lastname: Huang
authors.affiliation: Oncology Center for Pediatric Clinical Effectiveness, The Children's Hospital of Philadelphia, Pennsylvania Department of Pediatrics Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia.
authors.forename: Richard
authors.initials: R
authors.lastname: Aplenc
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization; D006776:Hospitals, Pediatric; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007251:Influenza, Human / Q000453:epidemiology*; D007902:Length of Stay; D008137:Longitudinal Studies; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000150:complications / Q000401:mortality*; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: epidemiology; hospitalizations; influenza; leukemia; pediatrics