In Search of Efficiency, Consistency, Fairness, and Impact in
HTA: Modelling screening and treatment pathways for diabetic
retinopathy Graham Scotland
Slide 2
Acknowledgments Dr Helen Looker (University of Dundee)
Professor Helen Colhoun (University of Dundee) Professor Paul
McKeigue (University of Edinburgh) Professor Graham Leese (NHS
Tayside) Dr John Olson (NHS Grampian) Dr Sam Philip (NHS Grampain)
The work being presented was funded by the Chief Scientist Office
of the Scottish Government Health and Social Care Directorates. The
author accepts full responsibility for this presentation. I am not
aware of any actual or potential conflicts of interest in relation
to this presentation
Slide 3
Background Diabetic retinopathy / maculopathy a leading cause
of visual loss and blindness proliferative retinopathy macular
oedema Early signs can be identified on retinal photographs Early
identification and treatment can reduce the risk of visual loss
Scottish National Screening Programme established in 2006
Slide 4
The Scottish diabetic retinopathy screening programme
Established in 2006, based on annual screening using digital
retinal photography Eligible screening population: 247,017 Number
screened 199,268 (8% increase on previous year) Prevalence of
diabetes growing by 4% annually ~4% of patients referable in one
annual round of screening
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DR treatment pathways Severe background retinoapthy (R3)
Monitor for progression to R4, and treat DMO if present
Proliferative retinopathy (R4) Pan-retinal photogoagulation
Vitrectomy (for complications of PDR) Maculopathy (M2) / diabetic
macular oedema (DMO) Monitor Focal laser treatment (prevent
moderate visual loss) Intravitreal Anti-VEGF injections (for
symptomatic disease)
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Cost-effectiveness of risk stratified screening intervals Risk
of progression to referable disease associated with: type of
diabetes, duration of diabetes, sex, current observed grade, prior
observed grade (Looker et al., 2013)* Large proportion of the
current annual screening cohort have progression risk < 1% Scope
exists to improve efficiency of screening by adopting risk
stratified screening intervals *Looker HC et al. Predicted impact
of extending the screening interval for diabetic retinopathy: the
Scottish Diabetic Retinopathy Screening programme. Diabetologia.
2013; 56(8):1716-25
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Progression risks by sex, current/prior grade and duration of
Type 2 diabetes Current / prior grade Duration of diabetes (years)
Men - probability of any referable disease (%) Women - probability
of any referable disease (%) 1 year2 years1 year2 years Current
grade no DR / 00.140.390.140.37 50.200.640.230.69
100.260.900.311.04 150.311.130.381.38 Current grade no DR / Prior
grade no DR 00.070.250.080.25 50.110.430.130.48 100.140.610.180.74
150.180.780.241.00 Current grade no DR / Prior grade mild DR
00.420.960.320.68 50.822.090.761.80 101.243.421.313.40
151.614.631.845.04 *Looker HC et al. Predicted impact of extending
the screening interval for diabetic retinopathy: the Scottish
Diabetic Retinopathy Screening programme. Diabetologia. 2013;
56(8):1716-25
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Aim Model the clinical and cost-effectiveness of adopting
extended intervals for groups of patients defined by selected
clinical and demographic variables routinely available to screening
programmes.
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Conceptual screening model Starting cohort Non-referable
screening participants (age, sex, type of diabetes, duration of
diabetes, current / previous grade) In screening programmeReferred
M2 R3/R4 R3/R4 +DMO DMO No DMO R3 R4 Monitor Monitor / Treat
Monitor Treat/ Monitor Reduced risk of visual loss Non- referable
Referable M2 R3/R4 R3/R4 +DMO Treat/ Monitor Visual loss
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Some preliminary results
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Risk distribution in the annual screening cohort Risk Decile
Range of estimated one year risks of progression MinMax
10.0007310.000958 20.0010050.001154 30.0011680.0013 40.001370.00144
50.0015030.001733 60.0017460.002254 70.0022550.008196
80.0086340.026225 90.0262460.051352 100.0513780.360943
Total0.0007310.360943
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Cost-effectiveness of biennial versus annual screening by risk
decile Progression risk 0.8-2.6% Current practice: annual for all
Biennial for all
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Annual versus biennial screening by current / prior screened
grade Biennial for all with no DR / annual for everyone else
Biennial if no DR and no history of DR / annual for everyone else
Current practice: annual for everyone
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Summary of preliminary findings Annual screening appears
unlikely to be cost- effective against accepted cost per QALY
thresholds, if the 1-year forward risk of progression < ~1%
Individuals with no retinopathy and no history of retinopathy (55%
of the annual screening cohort) have an estimated risk