title: Proportion of hospital readmissions deemed avoidable: a systematic review.
abstract: BACKGROUND
  Readmissions to hospital are increasingly being used as an indicator of quality of care. However, this approach is valid only when we know what proportion of readmissions are avoidable. We conducted a systematic review of studies that measured the proportion of readmissions deemed avoidable. We examined how such readmissions were measured and estimated their prevalence.
  
  
  METHODS
  We searched the MEDLINE and EMBASE databases to identify all studies published from 1966 to July 2010 that reviewed hospital readmissions and that specified how many were classified as avoidable.
  
  
  RESULTS
  Our search strategy identified 34 studies. Three of the studies used combinations of administrative diagnostic codes to determine whether readmissions were avoidable. Criteria used in the remaining studies were subjective. Most of the studies were conducted at single teaching hospitals, did not consider information from the community or treating physicians, and used only one reviewer to decide whether readmissions were avoidable. The median proportion of readmissions deemed avoidable was 27.1% but varied from 5% to 79%. Three study-level factors (teaching status of hospital, whether all diagnoses or only some were considered, and length of follow-up) were significantly associated with the proportion of admissions deemed to be avoidable and explained some, but not all, of the heterogeneity between the studies.
  
  
  CONCLUSIONS
  All but three of the studies used subjective criteria to determine whether readmissions were avoidable. Study methods had notable deficits and varied extensively, as did the proportion of readmissions deemed avoidable. The true proportion of hospital readmissions that are potentially avoidable remains unclear.
authors: Faculty of Medicine, University of Ottawa, Ottawa, Ont. carlv@ohri.ca
authors: Carl
authors: C
authors: van Walraven
authors: Carol
authors: C
authors: Bennett
authors: Alison
authors: A
authors: Jennings
authors: Peter C
authors: PC
authors: Austin
authors: Alan J
authors: AJ
authors: Forster
mesh_terms: D006801:Humans; D010359:Patient Readmission / Q000592:standards / Q000706:statistics & numerical data; D019984:Quality Indicators, Health Care / Q000592:standards / Q000706:statistics & numerical data; D012044:Regression Analysis