title: Splenectomy and the risk of sepsis: a population-based cohort study.
abstract: OBJECTIVE
  We sought to estimate the long-term risk of sepsis in patients who underwent splenectomy before, during, and after implementation of vaccination.
  
  
  BACKGROUND
  Because patients who have undergone splenectomy are considered at increased risk of bacterial sepsis, they typically receive vaccination, education, and occasionally antibiotic prophylaxis. However, the extent to which these interventions have actually reduced the risk of sepsis remains unclear.
  
  
  METHODS
  Retrospective cohort study encompassing all patients in the Swedish national inpatient register, who underwent splenectomy in 1970-2009. Patients were followed for hospitalization for or death from sepsis, as identified using national inpatient and cause of death registers. Relative risks, comparing patients to the background population were expressed as standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs).
  
  
  RESULTS
  Altogether, 20,132 splenectomized patients were included. The overall SIR for hospitalization for sepsis was 5.7 [95% confidence interval (CI), 5.6-6.0]. However, risks depended on the indication for splenectomy, with SIRs varying from 3.4 (95% CI, 3.0-3.8) for trauma patients to 18 (95% CI, 16-19) for patients with hematologic malignancies. SMRs ranged from 3.1 (95% CI, 2.1-4.3) for trauma to 8.7 (95% CI, 6.8-11) for hematologic disease. In regression analyses adjusting for age at splenectomy, follow-up time, sex, and calendar year of splenectomy, there were no significant risk decreases after implementation of routine vaccination, except for in patients with malignant and non-malignant hematologic disease.
  
  
  CONCLUSIONS
  The risk of hospitalization or death from sepsis is high in patients who previously underwent splenectomy and depends on the indication for splenectomy. The effectiveness of current vaccination practices warrants further evaluation.
authors.affiliation: *Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden †Department of Epidemiology, Harvard School of Public Health, Boston, MA ‡Department of Medicine, Division of Hematology, Karolinska University Hospital, Stockholm §Saw Swee Hock School of Public Health, National University of Singapore, Singapore ¶Department of Surgery, National University of Singapore, Singapore; and ‖Department of Surgery, University of California, Davis, Medical Center, Sacramento, CA.
authors.forename: Gustaf
authors.initials: G
authors.lastname: Edgren
authors.forename: Rikke
authors.initials: R
authors.lastname: Almqvist
authors.forename: Mikael
authors.initials: M
authors.lastname: Hartman
authors.forename: Garth H
authors.initials: GH
authors.lastname: Utter
mesh_terms: D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D018805:Sepsis / Q000453:epidemiology / Q000209:etiology*; D013156:Splenectomy / Q000009:adverse effects*; D015996:Survival Rate / Q000639:trends; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult