title: Bias in Markov models of disease.
abstract: We examine bias in Markov models of diseases, including both chronic and infectious diseases. We consider two common types of Markov disease models: ones where disease progression changes by severity of disease, and ones where progression of disease changes in time or by age. We find sufficient conditions for bias to exist in models with aggregated transition probabilities when compared to models with state/time dependent transition probabilities. We also find that when aggregating data to compute transition probabilities, bias increases with the degree of data aggregation. We illustrate by examining bias in Markov models of Hepatitis C, Alzheimer's disease, and lung cancer using medical data and find that the bias is significant depending on the method used to aggregate the data. A key implication is that by not incorporating state/time dependent transition probabilities, studies that use Markov models of diseases may be significantly overestimating or underestimating disease progression. This could potentially result in incorrect recommendations from cost-effectiveness studies and incorrect disease burden forecasts.
authors.affiliation: Stewart School of Industrial and Systems Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0205, USA. dfaissol@isye.gatech.edu
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Faissol
authors.forename: Paul M
authors.initials: PM
authors.lastname: Griffin
authors.forename: Julie L
authors.initials: JL
authors.lastname: Swann
mesh_terms: D000367:Age Factors; D000465:Algorithms; D000544:Alzheimer Disease / Q000175:diagnosis; D015982:Bias; D003198:Computer Simulation; D018450:Disease Progression; D019698:Hepatitis C, Chronic / Q000175:diagnosis; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis; D008390:Markov Chains; D008954:Models, Biological; D009010:Monte Carlo Method; D011336:Probability; D012720:Severity of Illness Index; D013997:Time Factors