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.

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 very know…. I'm feeling very depressed ......nobody depressed ......nobody likes melikes 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”