title: Impact of socio-economic status on unplanned readmission following injury: A multicenter cohort study.
abstract: BACKGROUND
  Unplanned readmissions cost the US economy approximately $17 billion in 2009 with a 30-day incidence of 19.6%. Despite the recognised impact of socio-economic status (SES) on readmission in diagnostic populations such as cardiovascular patients, its impact in trauma patients is unclear. We examined the effect of SES on unplanned readmission following injury in a setting with universal health insurance. We also evaluated whether additional adjustment for SES influenced risk-adjusted readmission rates, used as a quality indicator (QI).
  
  
  METHODS
  We conducted a multicenter cohort study in an integrated Canadian trauma system involving 56 adult trauma centres using trauma registry and hospital discharge data collected between 2005 and 2010. The main outcome was unplanned 30-day readmission; all cause, due to complications of injury and due to subsequent injury. SES was determined using ecological indices of material and social deprivation. Odds ratios of readmission and 95% confidence intervals adjusted for covariates were generated using multivariable logistic regression with a correction for hospital clusters. We then compared a readmission QI validated previously (original QI) to a QI with additional adjustment for SES (SES-adjusted QI) using the mean absolute difference.
  
  
  RESULTS
  The cohort consisted of 52,122 trauma admissions of which 6.5% were rehospitalised within 30 days of discharge. Compared to patients in the lowest quintile of social deprivation, those in the highest quintile had a 20% increase in the odds of all-cause unplanned readmission (95% CI=1.06-1.36) and a 27% increase in the odds of readmission due to complications of injury (95% CI=1.04-1.54). No association was observed for material deprivation or for readmissions due to subsequent injuries. We observed a strong agreement between the original and SES-adjusted readmission (mean absolute difference= 0.04%).
  
  
  CONCLUSIONS
  Patients admitted for traumatic injury who suffer from social deprivation have an increased risk of unplanned rehospitalisation due to complications of injury in the 30 days following discharge. Better discharge planning or follow up for such patients may improve patient outcome and resource use for trauma admissions. Despite observed associations, results suggest that the trauma QI based on unplanned readmission does not require additional adjustment for SES.
authors.affiliation: Department of social and preventive medicine, Université Laval, Québec, QC, Canada; Axe Santé des Populations - Pratiques Optimales en Santé (Population Health - Practice - Changing Research Unit), Traumatologie - Urgence - Soins intensifs (Trauma - Emergency - Critical Care Medicine), Centre de Recherche du Centre Hospitalier Universitaire de Québec (CHU de Québec - Hôpital de l'Enfant-Jésus), Université Laval, Québec, QC, Canada. Electronic address: brahim.cisse.1@ulaval.ca.
authors.forename: Brahim
authors.initials: B
authors.lastname: Cisse
authors.affiliation: Department of social and preventive medicine, Université Laval, Québec, QC, Canada; Axe Santé des Populations - Pratiques Optimales en Santé (Population Health - Practice - Changing Research Unit), Traumatologie - Urgence - Soins intensifs (Trauma - Emergency - Critical Care Medicine), Centre de Recherche du Centre Hospitalier Universitaire de Québec (CHU de Québec - Hôpital de l'Enfant-Jésus), Université Laval, Québec, QC, Canada.
authors.forename: Lynne
authors.initials: L
authors.lastname: Moore
authors.affiliation: Department of social and preventive medicine, Université Laval, Québec, QC, Canada; Axe Santé des Populations - Pratiques Optimales en Santé (Population Health - Practice - Changing Research Unit), Traumatologie - Urgence - Soins intensifs (Trauma - Emergency - Critical Care Medicine), Centre de Recherche du Centre Hospitalier Universitaire de Québec (CHU de Québec - Hôpital de l'Enfant-Jésus), Université Laval, Québec, QC, Canada.
authors.forename: Brice Lionel Batomen
authors.initials: BL
authors.lastname: Kuimi
authors.affiliation: Department of social and preventive medicine, Université Laval, Québec, QC, Canada; Axe Santé des Populations - Pratiques Optimales en Santé (Population Health - Practice - Changing Research Unit), Traumatologie - Urgence - Soins intensifs (Trauma - Emergency - Critical Care Medicine), Centre de Recherche du Centre Hospitalier Universitaire de Québec (CHU de Québec - Hôpital de l'Enfant-Jésus), Université Laval, Québec, QC, Canada.
authors.forename: Teegwendé Valérie
authors.initials: TV
authors.lastname: Porgo
authors.affiliation: Department of social and preventive medicine, Université Laval, Québec, QC, Canada; Axe Santé des Populations - Pratiques Optimales en Santé (Population Health - Practice - Changing Research Unit), Traumatologie - Urgence - Soins intensifs (Trauma - Emergency - Critical Care Medicine), Centre de Recherche du Centre Hospitalier Universitaire de Québec (CHU de Québec - Hôpital de l'Enfant-Jésus), Université Laval, Québec, QC, Canada.
authors.forename: Amélie
authors.initials: A
authors.lastname: Boutin
authors.affiliation: Institut National d'Excellence en Santé et en Services Sociaux, Montréal, QC, Canada.
authors.forename: André
authors.initials: A
authors.lastname: Lavoie
authors.affiliation: Institut National d'Excellence en Santé et en Services Sociaux, Montréal, QC, Canada.
authors.forename: Gilles
authors.initials: G
authors.lastname: Bourgeois
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002170:Canada / Q000453:epidemiology; D005260:Female; D006801:Humans; D015601:Injury Severity Score; D007902:Length of Stay / Q000191:economics / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D010359:Patient Readmission / Q000191:economics / Q000706:statistics & numerical data*; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D012923:Social Class; D014193:Trauma Centers / Q000191:economics / Q000706:statistics & numerical data; D014947:Wounds and Injuries / Q000175:diagnosis / Q000191:economics / Q000628:therapy*; D055815:Young Adult
keywords: Injury; Performance evaluation; Socio–economic status; Trauma; Unplanned readmission