title: Quality of life and time trade-off utility measures in patients with coronary artery disease.
abstract: BACKGROUND
  Contemporary clinical trials commonly measure quality of life and medical costs to establish whether therapies are both effective and cost effective. Cost-effectiveness analysis, however, requires a measure of patient utility or preferences for various health states. Because utilities are not often measured directly, we sought to develop a method of translating standard quality-of-life scales into a patient utility measure.
  
  
  METHODS
  Five hundred fifty-three patients enrolled in the Bypass Angioplasty Revascularization Investigation Study of Economics and Quality of Life completed a battery of quality-of-life measures and a time trade-off utility assessment an average of 7.3 years after random assignment.
  
  
  RESULTS
  The mean time trade-off score was 8.54 (SD = 2.53) out of a maximum of 10; median score was 9.95. The distribution of scores was skewed, with 12% of patients at the highest possible score of 10. Patients with recurrent angina had significantly lower time trade-off scores than patients without angina (mean 7.03 vs 8.70, P <.05). Time trade-off scores were moderately correlated with each quality-of-life measure (Spearman coefficients 0.38-0.52). Time trade-off scores could be predicted by combinations of 4 (r2 = 0.29), 5 (r2 = 0.31), or 6 (r2 = 0.32) variables.
  
  
  CONCLUSIONS
  Time trade-off utility scores can be inferred from commonly used quality-of-life measures. Angina significantly reduces patient utility scores.
authors.affiliation: Department of Health Research and Policy, Stanford University School of Medicine, Stanford, Calif 95305-5405, USA.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Melsop
authors.forename: Derek B
authors.initials: DB
authors.lastname: Boothroyd
authors.forename: Mark A
authors.initials: MA
authors.lastname: Hlatky
mesh_terms: D017677:Age Distribution; D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000523:psychology* / Q000628:therapy; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D017678:Sex Distribution; D013997:Time Factors