title: The development of a decision analytic model of changes in mean deviation in people with glaucoma: the COA model.
abstract: OBJECTIVE
  To create and validate a statistical model predicting progression of primary open-angle glaucoma (POAG) assessed by loss of visual field as measured in mean deviation (MD) using 3 landmark studies of glaucoma progression and treatment.
  
  
  METHODS
  A Markov decision analytic model using patient level data described longitudinal MD changes over 7 years.
  
  
  METHODS
  Patient-level data from the Collaborative Initial Glaucoma Treatment Study (n = 607), the Ocular Hypertension Treatment Study (OHTS; n = 148; only those who developed POAG in the first 5 years of OHTS) and Advanced Glaucoma Intervention Study (n = 591), the COA model.
  
  
  METHODS
  We developed a Markov model with transition matrices stratified by current MD, age, race, and intraocular pressure categories and used a microsimulation approach to estimate change in MD over 7 years. Internal validation compared model prediction for 7 years to actual MD for COA participants. External validation used a cohort of glaucoma patients drawn from university clinical practices.
  
  
  METHODS
  Change in visual field as measured in MD in decibels (dB).
  
  
  RESULTS
  Regressing the actual MD against the predicted produced an R(2) of 0.68 for the right eye and 0.63 for the left. The model predicted ending MD for right eyes of 65% of participants and for 63% of left eyes within 3 dB of actual results at 7 years. In external validation the model had an R(2) of 0.79 in the right eye and 0.77 in the left at 5 years.
  
  
  CONCLUSIONS
  The COA model is a validated tool for clinicians, patients, and health policy makers seeking to understand longitudinal changes in MD in people with glaucoma.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA. kymes@wustl.edu
authors.forename: Steven M
authors.initials: SM
authors.lastname: Kymes
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Lambert
authors.forename: Paul P
authors.initials: PP
authors.lastname: Lee
authors.forename: David C
authors.initials: DC
authors.lastname: Musch
authors.forename: Carla J
authors.initials: CJ
authors.lastname: Siegfried
authors.forename: Sameer V
authors.initials: SV
authors.lastname: Kotak
authors.forename: Dustin L
authors.initials: DL
authors.lastname: Stwalley
authors.forename: Joel
authors.initials: J
authors.lastname: Fain
authors.forename: Chris
authors.initials: C
authors.lastname: Johnson
authors.forename: Mae O
authors.initials: MO
authors.lastname: Gordon
mesh_terms: D000368:Aged; D002986:Clinical Trials as Topic; D003661:Decision Support Techniques; D018450:Disease Progression; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008390:Markov Chains; D008875:Middle Aged; D015233:Models, Statistical; D009798:Ocular Hypertension / Q000175:diagnosis / Q000503:physiopathology; D014786:Vision Disorders / Q000503:physiopathology; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology