title: Simulation of quality-adjusted survival in chronic diseases: an application in type 2 diabetes.
abstract: Recent studies have demonstrated that measures of health-related quality of life can predict complications and mortality in patients with diabetes, even after adjustment for clinical risk factors.
  
  
  
  The authors developed a simulation model of disease progression in type 2 diabetes to investigate the impact of patient quality of life on lifetime outcomes and its potential response to therapy. Changes in health utility over time are captured as a result of complications and aging. All risk equations, model parameter estimates, and input data were derived from patient-level data from the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial.
  
  
  
  Healthier patients with type 2 diabetes enjoy more life years, quality-adjusted life years (QALYs), and more life years free of complications. A 65-year-old patient at full health (utility = 1) can expect to live approximately 2 years longer and achieve 6 more QALYs than a patient at average health (utility = 0.8), given similar clinical risk factors. For patients with higher EQ-5D utility, the additional years lived without complications contribute more to longer life expectancy than years lived with complications.
  
  
  
  The authors have developed a model for progression of disease in diabetes that has a number of novel features; it captures the observed relationships between measures of quality of life and future outcomes, the number of states have been minimized, and it can be parameterized with just 4 risk equations. Underlying the simple model structure is important patient-level heterogeneity in health and outcomes. The simulations suggest that differences in patients' EQ-5D utility can account for large differences in QALYs, which could be relevant in cost-utility analyses.
authors.affiliation: School of Public Health, University of Sydney, NSW, Australia (AJH, PMC)
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Hayes
authors.affiliation: School of Public Health, University of Sydney, NSW, Australia (AJH, PMC)
authors.forename: Philip M
authors.initials: PM
authors.lastname: Clarke
authors.affiliation: NHMRC Clinical Trials Centre, University of Sydney, NSW, Australia (MV, AK)
authors.forename: Merryn
authors.initials: M
authors.lastname: Voysey
authors.affiliation: NHMRC Clinical Trials Centre, University of Sydney, NSW, Australia (MV, AK)
authors.forename: Anthony
authors.initials: A
authors.lastname: Keech
mesh_terms: D000368:Aged; D002908:Chronic Disease; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D019057:Quality-Adjusted Life Years; D016019:Survival Analysis