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Diabetic Retinopathy Screening in Scotland. Roderick Harvey DRS Lead Clinician. Population 5,144,200 . White paper 2000 Commitment to develop a Scottish Diabetes Framework “The framework will include plans to establish a national screening strategy for diabetic retinopathy”.
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Diabetic Retinopathy Screening in Scotland Roderick Harvey DRS Lead Clinician
Population 5,144,200
White paper 2000 Commitment to develop a Scottish Diabetes Framework “The framework will include plans to establish a national screening strategy for diabetic retinopathy” The national programme
HTBS Report 2002 • Aim – detection of sight threatening diabetic retinopathy • Screening modalities • Primary - digital retinal photography • Secondary - slit lamp biomicroscopy
Benefits of photographic screening • High sensitivity and specificity for sight threatening disease • Ease of image acquisition, storage and transmission • The opportunity for quality assurance through double reading • Cost effectiveness
NHS QIS DRS Standards • Screening delivered to a defined specification • 80% of eligible people screened per year • 100% of eligible people invited per year • Call & recall in place using national software • Arrangements for hard to reach groups • Staff trained and qualified (or under supervision) • Quality assurance is in place
Special features • Single field macular centred image • Mydriasis only if initial image of inadequate quality
Grading • Feature based • Software calculates final grade according to grading algorithm • Outcome determined automatically • All graders perform full grading • Level 1 final grade normals only • Level 2 final grade non referrable • Level 3 final grade all referrable
Quality assurance • All L1 & L2 graders have 500 image pairs per year regraded randomly by L3 grader • External QA of images under development • 1st round of pilot completed 2008 • External QA of programmes • Standardised annual report template • National Key Performance Indicators
Training & Accreditation • City & guilds Level 3 Certificate in Diabetic Retinopathy Screening • 140 people in Scotland registered • 110 modules passed • Slit lamp examiner standards and accreditation process defined
The Scottish National DRS Programme • Responsibility for screening lies with the fourteen individual Health Boards • Within each Board the programme is delivered to common standards defined by • NHS QIS standards on DRS • Policies developed by the DRS Collaborative • Constraints embedded in the national DRS software • National software for photography, administration and grading
SGHD SDG NSD IT Board NSD DRS IT Board PFIG SCI-DC Executive Group Board Co-ordinators Clinical Group Short-life groups As required Service Management IT Users Group The Board Programmes are all members of a formal DRS Collaborative
Implications of franchise model • Adherence to national standards • Sharing of a national database of eligible patients • Ability to tailor the details of the delivery of the screening programme to suit local needs • Fixed site photography • Mobile units • Image capture through optometrists
Eligible population • All people resident in Scotland with confirmed diabetes • Aged 12 years or older • Not under the care of an ophthalmologist for treatment of diabetic retinopathy • Not suspended for a valid clinical or organisational reason (excludes temporarily unavailable)
Maintenace of the eligible population • Recording of diabetes in a primary care system automatically registers the patient for DRS • Dynamic link with SCI-DC and the CHI ensures that the population is accurately maintained • Registration can also be done directly through SCI-DC or Soarian • Suspensions are managed through SCI-DC and Soarian
Consortia server CHI Staging Server Soarian EMIS XML Messages Vision GPASS SCI-DC Mobile Admin Fixed SCI-DC Soarian
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Total living diabetic population 239,495 Eligible population 204,817
Invitation rate 93.2% Attendance rate 77.0% Successful screening rate 73.7%
Overall Referable 3.5% Observable 1.9% Tech failure 7.6%
Slit lamp examination • About 8% of patients require slit lamp examination • Training & accreditation requirements defined • Difficulty for small and dispersed boards in meeting the requirements
Optometry • Most optometrists now have digital retinal cameras • Photography is part of GOS contract for over 60s • Opportunities for synergy and image capture by optometrists • Challenges of integration with board wide screening programmes without compromise of quality standards on grading • Framework for optometry image capture is being piloted in two health board regions
Ophthalmlogy • Closing the loop • Capturing outcome of ophthalmology consultations • Ensuring appropriate suspension of patients under the care of ophthalmology • Failsafe to track ophthalmology referrals • Capacity
Quality assurance • Need for more robust analysis of internal QA performance across all health boards • Need to establish regular external QA image sets and define reporting formats
Start Image of adequate quality? Yes Refer to Level 2 Manual Grader No Microaneurysms present? Yes No Final Grade R0 M0
Automated Grading • 6732 patients using gold standard grading for actionable retinopathy • Automated grading 97.9% • Routine manual 99.1% • 33,535 patients from the Scottish DRS service the performance of automated grading for actionable retinopathy was • Sensitivity 99.1% • Specificity 59%
Automated grading • DRS Collaborative commissioned an independent review of the performance of automated lesion detection software • Four patients from 33535 (0.012%) may have missed clinically relevant maculopathy • Cost to detect these patients in Scotland £275,000 pa • Conclusion that it should be used for DRS programme in Scotland