Diabetic retinopathy screening NSF-based training

The screening processTunde 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/articlesearch.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

• 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• 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 collectionLearning 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 8/88/888)

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