Transcript Diabetic retinopathy screening NSF-based training

Diabetic retinopathy screening
NSF-based training
The screening process
Tunde Peto
Head of Reading Centre
Confirm patient’s identity
• Retinal vessels are unique, so if wrong patient
is photographed, it is noticeable at follow-up!
• Use full name, date of birth, address
• If possible, use hospital ID/NHS number
• If patient has invitation letter, ask them to
show it to you
• Double check before pre-screening and then
pre-photography
• Notify manager immediately if you made a
mistake and fill out critical incident form
Consequences of wrong identification
• Patient’s confidentiality
• Cost of inappropriate referral for one patient
and no referral for those who might need
treatment
• There are also legal implications if you do
not document it properly
• Patient might not take the right message
home
• Trust in screening is affected
What if patient is unable to confirm?
• Ask carer/nurse to confirm
• Look for identifying factors such as
invitation letter
• Ask as much as you can from the patient
• Make sure you are extra cautious with
taking visual acuity, help them with images
in order to try to minimise the anxiety and
possible unnecessary referral
• Also respect dignity, privacy and
confidentiality
What to do if patient wishes to opt out?
• Always ask why the patient wishes to do so
• Respect their decision and document it
• Make sure they understand the
consequences of their action
• Try to make it a temporary opt out as
opposed to a permanent one
• Let your manager know and make sure the
patient is in the appropriate pathway
The Caldicott report
• In 1997 the Government published The Caldicott
Report. This report highlighted six key principles:
– Justify the purpose (s).
– Don’t use patient identifiable information unless it is
absolutely necessary.
– Use the minimum necessary patient-identifiable information.
– Access to patient identifiable information should be on a
strict need to know basis.
– Everyone with access to patient identifiable information
should be aware of their responsibilities.
– Understand and comply with the law.
• 16 specific recommendations
• Make sure you understand how these apply to your
screening
Complaints
• All screening sites should have access to all
documentation needed to comply with
complaints
• All screeners must be knowledgeable on
complaints procedures
• These must be followed when a patient
wishes to complain
Visual acuity
• See attached paper from Optometry
• Discuss it with your local screening co-ordinator
which VA testing method you are to use.
• http://www.optometry.co.uk/pages/articles/article
search.php
Drop instillation
Key issues for discussion
• Discuss the importance of precise use of ophthalmic
drops
• Discuss the infection that can occur after non-sterile
drop instillation
• Discuss and demonstrate proper drop instillation
Learning outcome
• Identify the appropriate method of instilling drops
• Able to demonstrate proper technique of drop
instillation
Pharmacology of mydriatic drops
Key issues for discussion
• Discuss key features of mydriasis
• Discuss the type of drops available for achieving
mydriasis
• Discuss eye and systemic conditions contraindicating
mydriasis
Learning outcome
• Develop knowledge related available mydriatic drops
• Use critical appraisal deciding on the use of mydriasis
Mydriatic drops
• These drops dilate the pupil and paralyse the
ciliary muscle; they vary in potency and duration
of action.
• Short-acting, relatively weak mydriatics, such as
tropicamide 0.5%, facilitate the examination of
the fundus of the eye: used in screening.
• Cyclopentolate 1% or atropine and
homatropine 1% are not used in diabetic
retinopathy screening routinely.
• Phenylephrine belongs to sympathomimetics
Cautions
• Darkly pigmented iris is more resistant to pupillary
dilatation and caution should be exercised to avoid
overdosage.
• Mydriasis may precipitate acute angle-closure
glaucoma in a very few patients, usually aged over
60 years and hypermetropic (long-sighted), who are
predisposed to the condition because of a shallow
anterior chamber.
• Phenylephrine may interact with systemically
administered monoamine-oxidase inhibitors.
• DRIVING: Patients should be warned not to drive
for 1–2 hours after mydriasis.
Side effects of antimuscarinic
drugs
• Ocular side-effects of mydriatics and cycloplegics
include transient stinging and raised intra-ocular
pressure; on prolonged administration, local irritation,
hyperaemia, oedema and conjunctivitis may occur.
Contact dermatitis (conjunctivitis) is not uncommon with
the antimuscarinic mydriatic drugs, especially atropine.
• Toxic systemic reactions to atropine and cyclopentolate
may occur in the very young and the very old.
Side effects of phenylephrine
hydrochloride
• In children, in elderly and in cardiovascular
disease avoid 10% strength; use cautiosly in
tachycardia; hyperthyroidism; diabetes.
• Contra-indications: angle-closure glaucoma
• Side-effects: eye pain and stinging; blurred
vision, photophobia; systemic effects include
arrhythmias, hypertension, coronary artery
spasm.
Before instilling the drops
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Check the identity of the drops and expiry date
Check that it has been stored correctly
Check if the drop is safe to use in the patient by:
Always check if patient is allergic to any components of
the drops
Establish if the patient has an iris clip lens
Ask if they have angle closure glaucoma
Check the eye, if it is red and inflammed before drop
dilation, it is usually better to postpone the screening and
ask the patient to attend the appropriate clinical pathway
If there is an incident with the drop, you must fill out a
critical incident form and get the patient seen
Technology: computers, digital
camera, database
Key issues for discussion
• Discuss key features of the computers and programmes
required for screening
• Discuss the type of digital camera used for screening
• Discuss the database requirements for screening
purposes
Learning outcome
• Develop knowledge related technology used in a
screening programme
• Use critical appraisal deciding on technology needed
Ophthalmic photography: Fundus
photography
Key issues for discussion
• Discuss the use of photography in ophthalmology
• Discuss techniques used for ophthalmic photography including
stereo images
• Discuss common photographic errors and their relevance to
grading
Learning outcome
• Able to identify stereo images
• Able to identify artefacts and other common photographic errors
• Able to make informed judgement on grading photographs with
errors
Digital Imaging
Key issues for discussion
• Discuss key features of stereo film imaging and digital
imaging
• Discuss the advantages and disadvantages of digital
imaging
Learning outcome
• Develop knowledge related to different type of imaging
• Use critical appraisal in relation to imaging system
Photo versus digital
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Raging battle
Digital HAS to be better because it is digital
Very few studies looked into this in detail
Digital: bigger image, easy but costly to store, BUT no
stereo, easy to modify, large server needed, patient
confidentiality!
• Photo: smaller image, no way of modifying,
cumbersome to keep, BUT stereo image and no need to
change the software regularly, always retrievable
• For screening purposes: approved digital systems must
be used
Fundus photography system
• Ophthalmology: March 2002, 109(3) 595-601
– Film vs digital: good for referral decision
• Ophthalmology: Febr 2002, 109(2) 267-274
– Stereo digital vs biomicroscopy good in CSMO
• Acta Ophthalmol Scan.: 2000, 78: 164-168
– Digital images undergraded, less reliable
• Diab Tech @ Ther 1999 1(4): 477-487
– Nonmydriatic monochromatic image is good for HR cases
• Diabetes care: March 2000, 23(3) 345-348
– Telemedicine: ‘only few missed’
Basic camera maintenance
Key issues for discussion
• Discuss the camera to be used for screening
• Discuss basic principles of camera
maintenance and its impact on imaging
Learning outcome
• Able to carry out basic camera maintenance
Data acquisition: Data
management
Key issues for discussion
• Discuss the concept of “data” in epidemiological
studies
• Discuss continuous and categorical variables
• Discuss the difference between coding for “no
abnormality” – “not applicable” – “missing” and their
bearing on the analysis of the results
• Discuss the need for systematic data collection
Learning outcome
• Able to design small datasheet and critically evaluate
the values to be used
What are data ? What is
information?
• ‘Data' and 'information' are often used
synonymously, nowadays it is becoming
increasingly more common to think of 'data' as
the raw facts that have been collected; sometimes
from different sources and sometimes unrelated to
each other. The result of 'processing' the data is to
provide 'information';
• It is this information that is required to help with
the decision-making or inferential process.
Types of Data
• Continuous
– “measurement” data – eg IOP, age
• Categorical / Discrete
– “nominal” - named data – eg eye colour
– “ordinal” – can be ordered – eg Snellen VA
Types of Data continued
• Independent
– Data from different people
• Dependent
– Data from the same person
– eg: right and left eyes
– eg: IOP before and after treatment
Why does it matter?
• Different sorts of data are analysed in
different ways
• Different statistical packages require data in
different formats
What does the type of analysis
depend on?
• The question being asked
• The type of data that you have collected
• The amount of data that you have collected
– if you have little prior information
regarding the distribution of the data
How can statisticians help you?
• Statistical analysis will be easy if the data is
collected in the correct format
• It can take enormous effort to “clean” data
• Sometimes easier to re-input data
Where else can I get advice?
• Ophthalmic Research Network – in the medical
statistics section of the Governance section
(undergoing update)
– http://www.site4sight.org.uk/Quality/RGov/Stat.htm
• BMJ website
– http://bmj.com/collections/statsbk/index.shtml
– http://bmj.com/cgi/collection/statistics
• BMJ Statistics Notes
– http://bmj.com/all.shtml : search for Statistics Notes in the
“ Word(s) in Title or Abstract” field
What can go wrong?
• All data collected as text fields
• Too many variables included in database
• Forget to collect something vital in analysis
No abnormality/missing/not
appicable
• No abnormality: the question was asked and the patient
answered/tested negative:
– Have you ever had a heart attack: NO (code as 0)
• Missing: the question was not asked at all and so there
is no valid answer
– Patient terminated the interview before all questions were
asked, so unanswered questions are missing (code as
9/99/999)
• Not applicable: Questions about pregnancy in male
patients
– Have you ever had a low birthweight baby? (code as
What not to do
• Don’t play with statistical packages (eg
SPSS) unless you know what you are doing
• Don’t simply follow analyses in published
papers (they may be wrong)
• Don’t leave your analysis until the day
before you wish to send an abstract
somewhere.
Data acquisition: Database design
and development
Key issues for discussion
• Discuss the basics of database programs
• Discuss the need for the development of databases for
epidemiological studies
• Discuss how data management, study design and planned
statistical analysis influence each other
Learning outcome
• Able to discuss the database need for the small datasheet
designed in data management section
Why Have a Database?
• We rely on the importance of information and its
availability.
• A database is basically a filing cabinet for that
information which can be accessed via networked
computers, intranets and the intranet.
• It means that information is readily available at the
touch of a key.
• It also means that you are able to be more
selective about the information that you retrieve.
Managing a Clean Database
• ‘Rubbish in - rubbish out.’
• Inaccurately entered information, will undoubtedly have
an effect on the final results of any study.
• If data is entered badly, the results of the study will be
inconclusive.
• Data should be double or even triple entered or checked,
in order to produce a clean database, otherwise the study
will have been a complete waste of time, effort and
money.
• Making data entry as simple and as straight forward as
possible is the easiest way to prevent bad data being
entered.
Designing a Clean Database
• Drop down boxes: work by giving the data entry person
the choice of codes, numbers or words relevant to a
particular field. They are useful to doubly confirm a
field is entered in the correct manner, but it can be time
consuming. They restrict the opportunity for error, by
limiting the available keying options to those stored in
the list.
• Locking the Database: Locking the database ensures
that each field is completed in the correct manner.
Although this does not - in any way - guarantee that
fields have the correct information entered.
Designing a Clean Database
• Matching Tab Order: Tab order in the database should
match the running order of the data sheet, from which
data is being entered. This assists the person(s) entering
the data to obtain some sort of running order in which
data is keyed. Data entry then becomes consistent,
which minimises the risk of mistakes.
• Do not ‘Crowd’ the Page: If the database has been
designed well then a page should not be crowded. By
keeping a database sheet clean and simple, it makes it
easier for the data entry person to scan for errors after
each sheet has been completed. Data is much easier to
enter if the database screen is kept to one sheet only.
Anything more than this greatly improves the
opportunity for errors.
Designing a Clean Database
• Automatic Wording or Coding:if a word or code
needs to be repeatedly entered, programme likely
words into the database so that it completes the
word after the first letter is keyed. For instance,
if on every database sheet a field needed to be
completed with a person’s name, the database
could then automatically make the appropriate
selection after the first one or two letters is
keyed.
The overall importance of designing
and planning
• Well-designed database and careful planning assist in achieving and
providing accurate results.
• When considering your database design clearly defined study
objectives and outcome measures need to be known.
• Statistical plan should be in place for data analysis and ideally meet
with a statistician beforehand for some practical advice.
• Be aware of the data availability from your data-collecting source
and confirm that all necessary fields will be able to be completed.
• Enter a small amount of data as a test in the beginning of a study to
check the validity of the database.
• Regularly monitor the data in order to deal swiftly with any
problems or to make any necessary amendments to the database.
Research Procedure
• Old days
• Nowadays
• Why the change?
Old Research “Procedure”
• Researchers designed their own databases
• Collected lots of information
• Conducted lots of different analyses looking at
many different questions
• Published “statistically significant” results
Current Procedures
• If you are going to collect data on patients
you will need first to get ethical approval
• Before this you need to register a project
with the Research & Development
Department or equivalent if you are doing
research in where this department is not
available
Ethics Committee approval
• Completion of the ethics application forms will
help to ensure that you focus your research and
have a specific research question at the outset
• You can get access to statistical / IT support if
necessary
• Always good to consult a statistician prior to data
collection
Why has the procedure changed?
• May seem like a tedious process, but it may
protect you in the long term
• A few high publicity cases have illustrated what
can go wrong
– Bristol paediatric cardiology unit
– Alder Hey – retention of organs
– North Staffordshire neonatal ventilation study
• Research Governance now compulsory for all