title: Causes and patterns of readmissions in patients with common comorbidities: retrospective cohort study.
abstract: OBJECTIVE
  To evaluate the primary diagnoses and patterns of 30 day readmissions and potentially avoidable readmissions in medical patients with each of the most common comorbidities.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Academic tertiary medical centre in Boston, 2009-10.
  
  
  METHODS
  10,731 consecutive adult discharges from a medical department.
  
  
  METHODS
  Primary readmission diagnoses of readmissions within 30 days of discharge and potentially avoidable 30 day readmissions to the index hospital or two other hospitals in its network.
  
  
  RESULTS
  Among 10,731 discharges, 2398 (22.3%) were followed by a 30 day readmission, of which 858 (8.0%) were identified as potentially avoidable. Overall, infection, neoplasm, heart failure, gastrointestinal disorder, and liver disorder were the most frequent primary diagnoses of potentially avoidable readmissions. Almost all of the top five diagnoses of potentially avoidable readmissions for each comorbidity were possible direct or indirect complications of that comorbidity. In patients with a comorbidity of heart failure, diabetes, ischemic heart disease, atrial fibrillation, or chronic kidney disease, the most common diagnosis of potentially avoidable readmission was acute heart failure. Patients with neoplasm, heart failure, and chronic kidney disease had a higher risk of potentially avoidable readmissions than did those without those comorbidities.
  
  
  CONCLUSIONS
  The five most common primary diagnoses of potentially avoidable readmissions were usually possible complications of an underlying comorbidity. Post-discharge care should focus attention not just on the primary index admission diagnosis but also on the comorbidities patients have.
authors.affiliation: Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, MA 02120, USA.
authors.forename: Jacques
authors.initials: J
authors.lastname: Donzé
authors.forename: Stuart
authors.initials: S
authors.lastname: Lipsitz
authors.forename: David W
authors.initials: DW
authors.lastname: Bates
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Schnipper
mesh_terms: D000046:Academic Medical Centers; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001900:Boston; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010351:Patient Discharge / Q000706:statistics & numerical data*; D010359:Patient Readmission / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D013997:Time Factors