title: The impact of post-operative sepsis on mortality after hospital discharge among elective surgical patients: a population-based cohort study.
abstract: BACKGROUND
  Our aim in the present study was to assess the mortality impact of hospital-acquired post-operative sepsis up to 1 year after hospital discharge among adult non-short-stay elective surgical patients.
  
  
  METHODS
  We conducted a population-based, retrospective cohort study of all elective surgical patients admitted to 82 public acute hospitals between 1 January 2007 and 31 December 2012 in New South Wales, Australia. All adult elective surgical admission patients who stayed in hospital for ≥4 days and survived to discharge after post-operative sepsis were identified using the Admitted Patient Data Collection records linked with the Registry of Births, Deaths, and Marriages. We assessed post-discharge mortality rates at 30 days, 60 days, 90 days and 1 year and compared them with those of patients without post-operative sepsis.
  
  
  RESULTS
  We studied 144,503 survivors to discharge. Of these, 1857 (1.3%) had experienced post-operative sepsis. Their post-discharge mortality rates at 30 days, 60 days, 90 days and 1 year were 4.6%, 6.7%, 8.1% and 13.5% (vs 0.7%, 1.2%, 1.5% and 3.8% in the non-sepsis cohort), respectively (P < 0.0001 for all). After adjustment for patient and hospital characteristics, post-operative sepsis remained independently associated with a higher mortality risk (30-day mortality HR 2.75, 95% CI 2.14-3.53; 60-day mortality HR 2.45, 95% CI 1.94-3.10; 90-day mortality HR 2.31, 95% CI 1.85-2.87; 1-year mortality HR 1.71, 95% CI 1.46-2.00). Being older than 75 years of age (HR 3.50, 95% CI 1.56-7.87) and presence of severe/very severe co-morbidities as defined by Charlson co-morbidity index (severe vs normal HR 2.05, 95% CI 1.45-2.89; very severe vs normal HR 2.17, 95% CI 1.49-3.17) were the only other significant independent predictors of increased 1-year mortality.
  
  
  CONCLUSIONS
  Among elective surgical patients, post-operative sepsis is independently associated with increased post-discharge mortality up to 1 year after hospital discharge. This risk is particularly high in the first month, in older age patients and in the presence of severe/very severe co-morbidities. This high-risk population can be targeted for interventions.
authors.affiliation: Simpson Centre for Health Services Research, South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia. lixin.ou@unsw.edu.au.|Ingham Institute for Applied Medical Research, Liverpool, New South Wales, Australia. lixin.ou@unsw.edu.au.
authors.forename: Lixin
authors.identifier: http://orcid.org/0000-0002-1554-7899
authors.initials: L
authors.lastname: Ou
authors.affiliation: Simpson Centre for Health Services Research, South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia.|Ingham Institute for Applied Medical Research, Liverpool, New South Wales, Australia.
authors.forename: Jack
authors.initials: J
authors.lastname: Chen
authors.affiliation: Simpson Centre for Health Services Research, South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia.|Ingham Institute for Applied Medical Research, Liverpool, New South Wales, Australia.
authors.forename: Ken
authors.initials: K
authors.lastname: Hillman
authors.affiliation: Intensive Care Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia.|Faculty of Health Sciences, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Arthas
authors.initials: A
authors.lastname: Flabouris
authors.affiliation: Intensive Care Unit, Liverpool Hospital, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Parr
authors.affiliation: Epidemiology and Health Analytics, South Western Sydney Local Health District, Sydney, New South Wales, Australia.
authors.forename: Hassan
authors.initials: H
authors.lastname: Assareh
authors.affiliation: School of Medicine, University of Melbourne, Parkville, Melbourne, Victoria, Australia.
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Bellomo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D015331:Cohort Studies; D003428:Cross Infection / Q000401:mortality; D017558:Elective Surgical Procedures / Q000009:adverse effects*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009517:New South Wales / Q000453:epidemiology; D010351:Patient Discharge / Q000706:statistics & numerical data; D016012:Poisson Distribution; D011183:Postoperative Complications / Q000453:epidemiology* / Q000401:mortality; D016016:Proportional Hazards Models; D012042:Registries / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors; D018805:Sepsis / Q000453:epidemiology* / Q000401:mortality