title: Modelling the cost-effectiveness of adopting risk-stratified approaches to extended screening intervals in the national diabetic retinopathy screening programme in Scotland.
abstract: To assess the cost-effectiveness of adopting risk-stratified approaches to extended screening intervals in the national diabetic retinopathy screening programme in Scotland.
  
  
  
  A continuous-time hidden Markov model was fitted to national longitudinal screening data to derive transition probabilities between observed non-referable and referable retinopathy states. These were incorporated in a decision model simulating progression, costs and visual acuity outcomes for a synthetic cohort with a covariate distribution matching that of the Scottish diabetic screening population. The cost-effectiveness of adopting extended (2-year) screening for groups with no observed retinopathy was then assessed over a 30-year time horizon.
  
  
  
  Individuals with a current grade of no retinopathy on two consecutive screening episodes face the lowest risk of progressing to referable disease. For the cohort as a whole, the incremental cost per quality-adjusted life year gained for annual vs. biennial screening ranged from approximately £74 000 (for those with no retinopathy and a prior observed grade of mild or observable background retinopathy) to approximately £232 000 per quality-adjusted life year gained (for those with no retinopathy on two consecutive screening episodes). The corresponding incremental cost-effectiveness ratios in the subgroup with Type 1 diabetes were substantially lower; approximately £22 000 to £85 000 per quality-adjusted life year gained, respectively.
  
  
  
  Biennial screening for individuals with diabetes who have no retinopathy is likely to deliver significant savings for a very small increase in the risk of adverse visual acuity and quality of life outcomes. There is greater uncertainty regarding the long-term cost-effectiveness of adopting biennial screening in younger people with Type 1 diabetes.
authors.affiliation: Health Economics Research Unit, University of Aberdeen, Aberdeen, UK.|Health Services Research Unit, University of Aberdeen, Aberdeen, UK.
authors.forename: G
authors.initials: G
authors.lastname: Scotland
authors.affiliation: Centre for Population Health Sciences, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, UK.
authors.forename: P
authors.initials: P
authors.lastname: McKeigue
authors.affiliation: Grampian Diabetes Research Unit, NHS Grampian, Aberdeen, UK.
authors.forename: S
authors.initials: S
authors.lastname: Philip
authors.affiliation: Diabetes and Endocrinology, NHS Tayside, Dundee, UK.
authors.forename: G P
authors.initials: GP
authors.lastname: Leese
authors.affiliation: Diabetes Retinal Screening, NHS Grampian, Aberdeen, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Olson
authors.affiliation: Division for Clinical & Population Sciences and Education (CPSE), University of Dundee, Dundee, UK.
authors.forename: H C
authors.initials: HC
authors.lastname: Looker
authors.affiliation: Division for Clinical & Population Sciences and Education (CPSE), University of Dundee, Dundee, UK.
authors.forename: H M
authors.initials: HM
authors.lastname: Colhoun
authors.affiliation: Health Economics Research Unit, University of Aberdeen, Aberdeen, UK.
authors.forename: M
authors.initials: M
authors.lastname: Javanbakht
mesh_terms: D000328:Adult; D000368:Aged; D003198:Computer Simulation; D003362:Cost-Benefit Analysis; D003661:Decision Support Techniques; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000628:therapy*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000628:therapy*; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D019468:Disease Management; D005260:Female; D006801:Humans; D008297:Male; D008390:Markov Chains; D008403:Mass Screening / Q000191:economics / Q000379:methods*; D008875:Middle Aged; D018803:Models, Economic; D012017:Referral and Consultation; D018570:Risk Assessment; D012606:Scotland; D013997:Time Factors