title: Systematic review and evaluation of physiological track and trigger warning systems for identifying at-risk patients on the ward.
abstract: OBJECTIVE
  Physiological track and trigger warning systems (TTs) are used to identify patients outside critical care areas at risk of deterioration and to alert a senior clinician, Critical Care Outreach Service, or equivalent. The aims of this work were: to describe published TTs and the extent to which each has been developed according to established procedures; to review the published evidence and available data on the reliability, validity and utility of existing systems; and to identify the best TT for timely recognition of critically ill patients.
  
  
  METHODS
  Systematic review of studies identified from electronic, citation and hand searching, and expert informants. Cohort study of data from 31 acute hospitals in England and Wales.
  
  
  RESULTS
  Thirty-six papers were identified describing 25 distinct TTs. Thirty-one papers described the use of a TT, and five were studies examining the development or testing of TTs. None of the studies met all methodological quality standards. For the cohort study, outcome was measured by a composite of death, admission to critical care, 'do not attempt resuscitation' or cardiopulmonary resuscitation. Fifteen datasets met pre-defined quality criteria. Sensitivities and positive predictive values were low, with median (quartiles) of 43.3 (25.4-69.2) and 36.7 (29.3-43.8), respectively.
  
  
  CONCLUSIONS
  A wide variety of TTs were in use, with little evidence of reliability, validity and utility. Sensitivity was poor, which might be due in part to the nature of the physiology monitored or to the choice of trigger threshold. Available data were insufficient to identify the best TT.
authors.affiliation: Intensive Care National Audit & Research Centre, Tavistock House, Tavistock Square, London, WC1H 9HR, UK.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Gao
authors.forename: Ann
authors.initials: A
authors.lastname: McDonnell
authors.forename: David A
authors.initials: DA
authors.lastname: Harrison
authors.forename: Tracey
authors.initials: T
authors.lastname: Moore
authors.forename: Sheila
authors.initials: S
authors.lastname: Adam
authors.forename: Kathleen
authors.initials: K
authors.lastname: Daly
authors.forename: Lisa
authors.initials: L
authors.lastname: Esmonde
authors.forename: David R
authors.initials: DR
authors.lastname: Goldhill
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Parry
authors.forename: Arash
authors.initials: A
authors.lastname: Rashidian
authors.forename: Christian P
authors.initials: CP
authors.lastname: Subbe
authors.forename: Sheila
authors.initials: S
authors.lastname: Harvey
mesh_terms: D018806:APACHE; D003422:Critical Care / Q000379:methods*; D016208:Databases, Factual; D004632:Emergency Medical Services / Q000706:statistics & numerical data*; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units