Improving the Value of Screening For Macular Oedema using Surrogate Photographic Markers Dr John Olson NHS Grampian
Jan 17, 2016
Improving the Value of Screening For Macular
Oedema usingSurrogate Photographic
Markers
Dr John Olson
NHS Grampian
Improving The Economic Value Of Photographic Screening For Optical Coherence Tomography
Detectable Macular Oedema – A Prospective Multicentre, United Kingdom Study
• Olson J, Sharp P , Goatman K, Prescott G, Scotland G, Fleming A, Philip S, Santiago C, Borooah S, Broadbent D, Chong V, Dodson P, Harding S, Leese G, Styles C, Swa K, Wharton H
• Health Technol Assess, Vol 17,, May- June 2013, In Press
A Success Story?
• Systematic screening programme for diabetic retinopathy
Missing the target?
• The health-economic case is based on the detection of people with, or at risk of– proliferative diabetic
retinopathy– before they develop
complications• Vitreous haemorrhage• Traction retinal detachment
• But 90% of referrals are for ? diabetic macular oedema
Why?
• Retinal photographs are not discriminatory for proliferative retinopathy or its precursors
• Other things may be present– e.g. diabetic “maculopathy”– We have to manage these findings
How did we get there?
• Retinopathy grades based on ETDRS
• Maculopathy grades basedon
…(GOBSAT)
Different management
New Vessels Oedema
Definitive treatment Indefinite treatment
Management independent of visual acuity
Management depended on visual acuity
2 D red structure 3 D transparent elevation
Few false +ves Many false +ves
What did ISMO question?
• Can we do it better?
• What will it cost?
• What will it mean?
The Answers In Short- Can Grading Schemes do it better ?
• Computer says nah
The Answers In Short- Can OCT do it better ?
• Yes• Increases the
specificity of referrals• With no loss of
sensitivity
The Answers-What will it cost?
• Less• If you use OCT • Whatever grading
strategy you use• Saves you money
The Answers- What will it mean?
Study Highlights
© 2008 Google-Imagery © 2008 TerraMetrics
Aberdeen
Dundee
Edinburgh
Liverpool
Birmingham
Oxford
Study centres
Aberdeen
Birmingham
Dundee
Edinburgh
Glasgow
Liverpool
Oxford
Glasgow
Every day practice
Aberdeen
Dundee
Edinburgh
Liverpool
Birmingham
Oxford
Glasgow
3450 Subjects
• Photographic signs of diabetic retinopathy– exudates ≤ 2DDr– blot haemorrhages ≤ 1DDr– dot haemorrhages/microaneurysms ≤ 1DDr
• Each subject had photography and optical coherence tomography on both eyes, where possible.
Patient Characteristics
• Median age 60
• 60.7% male
• 85.4% Caucasian
• 77.4% type 2 diabetes
370 Excluded (10.5%)
• 6 years older
• Female
• Asian/ Black
• Zeiss Stratus
• Topcon OCT 1000
Lesion Distribution
Expected % Recruited %
Ma/dot only 69.8 40.3
Blot no exudate 8.6 8.4
Exudate 21.6 20.4
No Ma/dot/blot/exudate ≤ 1DDr
28.1
Definition of Macular Oedema
• Central ETDRS region thickness > 250µm
• OR any of 5 inner regions > 300µm
• AND visible intraretinal cyst/ area of subretinal fluid
Prevalence of oedema
• 7.7% of study population
• Prevalence differed greatly by centre– 3.7% to 12.2%
• Prevalence differed greatly by scanner– 4.5% to 11.8%
Relationship to Centre
• Aberdeen 12.0%• Birmingham 3.7%• Dundee 12.2%• Edinburgh 6.4%• Liverpool 2.9%• Dunfermline 4.4%• Oxford 7.7%
All scanners are equal, but some scanners are more equal than others
• Zeiss Stratus– 4.5%
• Topcon OCT1000– 6.5%
• Heidelberg Spectralis– 8.7%
• Zeiss Cirrus– 11.8%
Relationship to patient features
• Older age– 68yrs cf 60
• Caucasian– 8.4% cf 3-4%
• Type 2 diabetes– 8.7% cf 3.9%
• Poorer vision– 5x more likely– If VA ≤ 6/9
• BUT NOT– Sex, glitazone, amblyopia
Relationship to Lesions
R Eye % L Eye %
No lesions
0.8 0.6
Ma/dot only
2.2 2.3
Blot no Exudate
10.2 11.2
Exudate 12.5 11.2
Other 1.1 1.1
Can we do any better?
• Three Grading Strategies Examined– Manual grading
• Presence/ absence of features• SDRGS 2007
– Computer-assisted manual annotation• All individual lesions ≤ 2DDr
– Fully automated annotation grading• Three versions
– Automated image analysis– +VA
– +VA + Age+ Type DM + Sex
Manual Grading (features)
Manual Grading (features)
• Scotland– 59.5% sensitivity– 79.0% specificity
• England– 72.6% sensitivity– 66.8% specificity
• England plus– 73.3% sensitivity– 70.9% specificity
Computer Assisted, Manual Annotation, Grading• Best for sensitivity &
specificity• Time-consuming
procedure • Unlikely to be
considered for routine screening practice
In Years To Come
Marvin the Manically Depressed Autograder
""I think you ought to I think you ought to know…. I'm feeling know…. I'm feeling very very depressed ......noboddepressed ......nobody likes mey likes me""
DRS in Scotland 2012
What will it cost?
• Cost per screen £33.13• Cost per OCT screen £31.96• Total cost for ?oedema £65.09
• Cost of attending ophthalmology £90.00
• (Cost of Slit lamp within DRS £27.29)
TABLE 30 Screening and referral cost per true case of macular oedema detected for 3,170 patients; Adjusted for expected frequency of different patient categories and based on Scottish screening and referral costs
* Reference strategy; a figures in table based on assumption that fully automated grading can be implemented at zero net increase in grading costs;++ Represents a cost saving per case missed relative to the reference strategy; d strategy more costly and less effective than an alternative strategy (dominated)
What does it mean?
• At present we spend £13,750,000 a year – 250,000 people @ £55– Screening + 1st visit to
ophthalmology– £2,337,500 on ? M2
• If we do nothing, other than introduce OCT into the screening pathway
• we save money
Should we grade differently?
Current Scottish Criteria + OCT is the most cost effective of all strategies
What if we do nothing? 20 year “M2” Markov Model• Only 5.6% of M2 at risk of visual loss• Repetitive nature of screening
– 12% of non-referred MO modelled to progress at 12 months cf 5% of referred (laser Rx)
• More sensitive strategies– More OCTs, more referrals
• Bilateral incidence 12%– QALY determined by VA in better seeing eye
• Additional cost per QALY going to strategy 16– £882,307 at 5 years– £353,927 at 20 years– (£20-30,00 UK threshold for “cost-effectiveness)
What should we do?
Cost-effectiveness acceptability curves for the alternative strategies based on a 20 year time horizon and using quality adjusted life years as the measure of effect
How should we manage M2s?Is this the answer?
• Photos graded as M2
• Check VA
• Do an OCT if VA 6/12 or worse?
• Otherwise rescreen in 6 months?
Thank You
Modelled visual acuity changes for “CSMO”