title: Sensitivity of diabetic retinopathy associated vision loss to screening interval in an agent-based/discrete event simulation model.
abstract: OBJECTIVE
  To examine the effect of changes to screening interval on the incidence of vision loss in a simulated cohort of Veterans with diabetic retinopathy (DR). This simulation allows us to examine potential interventions without putting patients at risk.
  
  
  METHODS
  Simulated randomized controlled trial. We develop a hybrid agent-based/discrete event simulation which incorporates a population of simulated Veterans--using abstracted data from a retrospective cohort of real-world diabetic Veterans--with a discrete event simulation (DES) eye clinic at which it seeks treatment for DR. We compare vision loss under varying screening policies, in a simulated population of 5000 Veterans over 50 independent ten-year simulation runs for each group.
  
  
  RESULTS
  Diabetic Retinopathy associated vision loss increased as the screening interval was extended from one to five years (p<0.0001). This increase was concentrated in the third year of the screening interval (p<0.01). There was no increase in vision loss associated with increasing the screening interval from one year to two years (p=0.98).
  
  
  CONCLUSIONS
  Increasing the screening interval for diabetic patients who have not yet developed diabetic retinopathy from 1 to 2 years appears safe, while increasing the interval to 3 years heightens risk for vision loss.
authors: VA St. Louis Healthcare System, USA. Electronic address: dayt@email.chop.edu.
authors: T Eugene
authors: TE
authors: Day
authors: VA St. Louis Healthcare System, USA; Washington University in St. Louis School of Medicine, USA.
authors: Nathan
authors: N
authors: Ravi
authors: VA St. Louis Healthcare System, USA; St. Louis University School of Public Health, USA.
authors: Hong
authors: H
authors: Xian
authors: VA St. Louis Healthcare System, USA.
authors: Ann
authors: A
authors: Brugh
mesh_terms: D000368:Aged; D003198:Computer Simulation; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000503:physiopathology; D003936:Diagnosis, Computer-Assisted; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D014728:Veterans; D015354:Vision, Low / Q000175:diagnosis* / Q000503:physiopathology
keywords: Agent based modeling; Diabetic eye screen; Diabetic retinopathy; Discrete event simulation