title: Relative distributions: a novel method for examining trends between stroke onset and thrombolysis time.
abstract: OBJECTIVE
  Analyses of trends in the delivery of time critical treatments typically report the median, but measures of central tendency may ignore important changes for specific patient groups. We considered whether this was an important effect during comparison of onset to treatment (OTT) time between 2 cohorts of patients with stroke receiving intravenous thrombolysis.
  
  
  METHODS
  After controlling for stroke severity, a relative distributions technique compared OTT for UK patients treated with recombinant tissue-type plasminogen activator registered within the first and last quarters (each n=661) of the Safe Implementation of Thrombolysis in Stroke-Monitoring Study database between January 2003 and September 2010.
  
  
  RESULTS
  Significant differences were found between OTT distributions. Overall, the second cohort's OTT distribution demonstrated simultaneous increases in the proportion of patients with faster and slower OTT, which resulted in no net effect on the median after correction for stroke severity.
  
  
  CONCLUSIONS
  Medians did not adequately describe distributional changes. Faster OTT may be because of more efficient processes in acute stroke centers and improved symptom recognition by the public. Slower OTT is likely to reflect movement from a 3- to a 4.5-hour OTT target. Relative distributions offer new insights into historical trends and service evaluation where time critical treatments are involved.
authors: From the Department of Healthcare, Northumbria University, Newcastle Upon Tyne, United Kingdom (P.M.); Newcastle University Business School, Newcastle Upon Tyne, United Kingdom (J.W.); Radcliffe Department of Medicine, University of Oxford, United Kingdom (G.A.F.); and Institute of Health and Society (L.V.) and Institute of Neuroscience (C.I.P.), Newcastle University, Newcastle Upon Tyne, United Kingdom. peter.mcmeekin@northumbria.ac.uk.
authors: Peter
authors: P
authors: McMeekin
authors: From the Department of Healthcare, Northumbria University, Newcastle Upon Tyne, United Kingdom (P.M.); Newcastle University Business School, Newcastle Upon Tyne, United Kingdom (J.W.); Radcliffe Department of Medicine, University of Oxford, United Kingdom (G.A.F.); and Institute of Health and Society (L.V.) and Institute of Neuroscience (C.I.P.), Newcastle University, Newcastle Upon Tyne, United Kingdom.
authors: John
authors: J
authors: Wildman
authors: From the Department of Healthcare, Northumbria University, Newcastle Upon Tyne, United Kingdom (P.M.); Newcastle University Business School, Newcastle Upon Tyne, United Kingdom (J.W.); Radcliffe Department of Medicine, University of Oxford, United Kingdom (G.A.F.); and Institute of Health and Society (L.V.) and Institute of Neuroscience (C.I.P.), Newcastle University, Newcastle Upon Tyne, United Kingdom.
authors: Gary A
authors: GA
authors: Ford
authors: From the Department of Healthcare, Northumbria University, Newcastle Upon Tyne, United Kingdom (P.M.); Newcastle University Business School, Newcastle Upon Tyne, United Kingdom (J.W.); Radcliffe Department of Medicine, University of Oxford, United Kingdom (G.A.F.); and Institute of Health and Society (L.V.) and Institute of Neuroscience (C.I.P.), Newcastle University, Newcastle Upon Tyne, United Kingdom.
authors: Luke
authors: L
authors: Vale
authors: From the Department of Healthcare, Northumbria University, Newcastle Upon Tyne, United Kingdom (P.M.); Newcastle University Business School, Newcastle Upon Tyne, United Kingdom (J.W.); Radcliffe Department of Medicine, University of Oxford, United Kingdom (G.A.F.); and Institute of Health and Society (L.V.) and Institute of Neuroscience (C.I.P.), Newcastle University, Newcastle Upon Tyne, United Kingdom.
authors: Christopher I
authors: CI
authors: Price
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003627:Data Interpretation, Statistical; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D020521:Stroke / Q000628:therapy*; D015912:Thrombolytic Therapy / Q000379:methods* / Q000639:trends; D061665:Time-to-Treatment; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use; D016896:Treatment Outcome; D006113:United Kingdom
chemical_list: D005343:Fibrinolytic Agents; D010959:Tissue Plasminogen Activator
keywords: thrombolysis, therapeutic