title: Using survival curve comparisons to inform patient decision making can a practice exercise improve understanding?
abstract: BACKGROUND
  Patients often face medical decisions that involve outcomes that occur and change over time. Survival curves are a promising communication tool for patient decision support because they present information about the probability of an outcome over time in a simple graphic format. However, previous studies of survival curves did not measure comprehension, used face-to-face explanations, and focused on a VA population.
  
  
  METHODS
  In this study, 246 individuals awaiting jury duty at the Philadelphia County Courthouse were randomized to receive one of two questionnaires. The control group received a questionnaire describing two hypothetical treatments and a graph with two survival curves showing the outcomes of each treatment. The practice group received the same questionnaire preceded by a practice exercise asking questions about a graph containing a single curve. Subjects' ability to interpret survival from a curve and ability to calculate change in survival over time were measured.
  
  
  RESULTS
  Understanding of survival at a single point in time from a graph containing two survival curves was high overall, and was improved by the use of a single curve practice exercise. With a practice exercise, subjects were over 80% accurate in interpreting survival at a single point in time. Understanding of changes in survival over time was lower overall, and was not improved by the use of a practice exercise. With or without a practice exercise, subjects were only 55% accurate in calculating changes in survival.
  
  
  CONCLUSIONS
  The majority of the general public can interpret survival at a point in time from self-administered survival curves. This understanding is improved by a single curve practice exercise. However, a significant proportion of the general public cannot calculate change in survival over time. Further research is necessary to determine the effectiveness of survival curves in improving risk communication and patient decision making.
authors.affiliation: Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, USA. karmstro@mail.upenn.edu
authors.forename: K
authors.initials: K
authors.lastname: Armstrong
authors.forename: G
authors.initials: G
authors.lastname: FitzGerald
authors.forename: J S
authors.initials: JS
authors.lastname: Schwartz
authors.forename: P A
authors.initials: PA
authors.lastname: Ubel
mesh_terms: D000328:Adult; D003657:Decision Making; D005260:Female; D006801:Humans; D008297:Male; D010358:Patient Participation; D011214:Practice, Psychological; D013223:Statistics as Topic; D011795:Surveys and Questionnaires; D015996:Survival Rate; D016896:Treatment Outcome