title: The hospital standardized mortality ratio fallacy: a narrative review.
abstract: BACKGROUND
  Outcome measures, like hospital standardized mortality ratios (HSMRs), are increasingly used to assess quality of care. The validity of HSMRs and their accuracy to reflect quality of care is heavily contested.
  
  
  OBJECTIVE
  We explored apparent and potential shortcomings and adverse effects of the HSMR in the assessment of quality of care.
  
  
  METHODS
  For this narrative review, relevant articles were collected from Medline databases using the following search terms: "hospital standardized mortality ratio," "standardized mortality ratio," "HSMR," "quality of care," and "in-hospital mortality." In addition, other important articles were subtracted from the reference lists of the primary articles.
  
  
  RESULTS
  The current literature exhibits important shortcomings of the HSMR that in particular affect hospitals providing specialized care of a certain level of complexity. Because of the lack or insufficiency of data concerning case-mix, coding variation between hospitals, disease severity, referral bias, end-of-life care, and place of death, the current HSMR model is not able to adjust adequately for these aspects. This leads to incomparability of HSMRs between hospitals. Instead of separate aspects of continuity of care, all factors contributing to quality of care should be considered.
  
  
  CONCLUSIONS
  Given the several shortcomings, use of the HSMR as an indicator of quality of care can be considered as a fallacy. Publication of the HSMR is not likely to lead to improvement of quality of care and might harm both hospitals and patients.
authors.affiliation: Eindhoven Cancer Registry, Comprehensive Cancer Center South (IKZ), Eindhoven, The Netherlands. y.van.gestel@ikz.nl
authors.forename: Yvette R B M
authors.initials: YR
authors.lastname: van Gestel
authors.forename: Valery E P P
authors.initials: VE
authors.lastname: Lemmens
authors.forename: Hester F
authors.initials: HF
authors.lastname: Lingsma
authors.forename: Ignace H J T
authors.initials: IH
authors.lastname: de Hingh
authors.forename: Harm J T
authors.initials: HJ
authors.lastname: Rutten
authors.forename: Jan Willem W
authors.initials: JW
authors.lastname: Coebergh
mesh_terms: D000367:Age Factors; D003953:Diagnosis-Related Groups / Q000706:statistics & numerical data; D017052:Hospital Mortality; D006801:Humans; D019984:Quality Indicators, Health Care; D011787:Quality of Health Care / Q000706:statistics & numerical data; D012017:Referral and Consultation / Q000706:statistics & numerical data; D012720:Severity of Illness Index; D012737:Sex Factors; D012959:Socioeconomic Factors; D013727:Terminal Care / Q000706:statistics & numerical data