Screening

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Screening

• Jo Pollott
• 31st May 2006

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Outline

• Why do we need to screen?
• Who decides what conditions should be screened
  for?
• How is it done?
• When is it done?
• When screening can do more harm than good
• Current UK screening programmes
• Conditions specifically not screened for

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Definition

• Screening is a public health service in which
  members of a defined population, who do not
  necessarily perceive they are at risk of, or are
  already affected by a disease or its
  complications, are asked a question or offered a
  test, to identify those individuals who are more
  likely to be helped than harmed by further tests
  or treatment to reduce the risk of a disease or
  its complications.

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UK National Screening Committee

• chaired by one of the Chief Medical Officers
• advises Ministers, the devolved national
  Assemblies and the Scottish Parliament on all
  aspects of screening policy
• has Fetal Maternal and Child Health Co-ordinating
  Group (FMCH) which deals with antenatal and child
  health screening issues
• draws on the latest research evidence and the
  skills of specially convened multi-disciplinary
  expert groups, which always include patient and
  service user representatives
• assesses proposed new screening programmes
  against a set of internationally recognised
  criteria
• ensures that they do more good than harm at a
  reasonable cost
• 1996 - NHS was instructed not to introduce any
  new screening programmes until the NSC had
  reviewed their effectiveness

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Criteria for screening

• Defined by WHO 1968
• Wilson-Jungner criteria

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Wilson-Jungner Criteria

• The condition being screened for should be an
  important health problem
• The natural history of the condition should be
  well understood
• There should be a detectable early stage
• Treatment at an early stage should be of more
  benefit than at a later stage
• A suitable test should be devised for the early
  stage
• The test should be acceptable
• Intervals for repeating the test should be
  determined
• Adequate health service provision should be made
  for the extra clinical workload resulting from
  screening
• The risks, both physical and psychological,
  should be less than the benefits
• The costs should be balanced against the benefits

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Criteria for appraising the viability,
effectiveness and appropriateness of a screening
programme 2003 - the Condition

• The condition should be an important health
  problem
• The epidemiology and natural history of the
  condition, including development from latent to
  declared disease, should be adequately understood
  and there should be a detectable risk factor,
  disease marker, latent period or early
  symptomatic stage
• All the cost-effective primary prevention
  interventions should have been implemented as far
  as practicable
• If the carriers of a mutation are identified as a
  result of screening the natural history of people
  with this status should be understood, including
  the psychological implications.

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Criteria for appraising the viability,
effectiveness and appropriateness of a screening
programme 2003 - the Test

• There should be a simple, safe, precise and
  validated screening test
• The distribution of test values in the target
  population should be known and a suitable cut-off
  level defined and agreed
• The test should be acceptable to the population
• There should be an agreed policy on the further
  diagnostic investigation of individuals with a
  positive test result and on the choices available
  to those individuals
• If the test is for mutations the criteria used to
  select the subset of mutations to be covered by
  screening, if all possible mutations are not
  being tested for, should be clearly set out

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Criteria for appraising the viability,
effectiveness and appropriateness of a screening
programme 2003 - the Treatment

• There should be an effective treatment or
  intervention for patients identified through
  early detection, with evidence of early treatment
  leading to better outcomes than late treatment
• There should be agreed evidence-based policies
  covering which individuals should be offered
  treatment and the appropriate treatment to be
  offered
• Clinical management of the condition and patient
  outcomes should be optimised in all healthcare
  providers prior to participation in a screening
  programme.

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Criteria for appraising the viability,
effectiveness and appropriateness of a screening
programme 2003 - the Screening programme 1

• There should be evidence from high-quality
  randomised controlled trials that the screening
  programme is effective in reducing mortality or
  morbidity. Where screening is aimed solely at
  providing information to allow the person being
  screened to make an 'informed choice' (for
  example, Down's syndrome and cystic fibrosis
  carrier screening), there must be evidence from
  high-quality trials that the test accurately
  measures risk. The information that is provided
  about the test and its outcome must be of value
  and readily understood by the individual being
  screened
• There should be evidence that the complete
  screening programme (test, diagnostic procedures,
  treatment/intervention) is clinically, socially.
  and ethically acceptable to health professionals
  and the public
• The benefit from the screening programme should
  outweigh the physical and psychological harm
  (caused by the test, diagnostic procedures and
  treatment)
• The opportunity cost of the screening programme
  (including testing, diagnosis and treatment,
  administration, training and quality assurance)
  should be economically balanced in relation to
  expenditure on medical care as a whole (ie value
  for money)
• There should be a plan for managing and
  monitoring the screening programme and an agreed
  set of quality assurance standards

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Criteria for appraising the viability,
effectiveness and appropriateness of a screening
programme 2003 - the Screening programme 2

• Adequate staffing and facilities for testing,
  diagnosis, treatment, and programme management
  should be available prior to the commencement of
  the screening programme
• All other options for managing the condition
  should have been considered (for example,
  improving treatment and providing other
  services), to ensure that no more cost-effective
  intervention could be introduced or current
  interventions increased within the resources
  available
• Evidence-based information, explaining the
  consequences of testing, investigation, and
  treatment, should be made available to potential
  participants to assist them in making an informed
  choice
• Public pressure for widening the eligibility
  criteria for reducing the screening interval, and
  for increasing the sensitivity of the testing
  process, should be anticipated. Decisions about
  these parameters should be scientifically
  justifiable to the public
• If screening is for a mutation, the programme
  should be acceptable to people identified as
  carriers and to other family members

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Limitations of screening

• not a fool-proof process
• can reduce the risk of developing a condition or
  its complications but it cannot offer a guarantee
  of protection
• irreducible minimum of false positive results and
  false negative results

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When screening can do more harm than good

• Whole body CT
• Whole body MRI
• Exercise ECG
• PSA testing for prostate cancer
• Mammography if lt50 yrs old

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Current NHS Screening Programmes

• Antenatal
• Neonatal
• Child
• Adult
• Breast cancer
• Cervical cancer

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Antenatal maternal screening

• Anaemia (early pregnancy 28 wks)
• Blood group Rhesus status (early pregnancy)
• Atypical alloantibodies (early pregnancy 28
  wks)
• Asymptomatic bacteriuria
• Hepatitis B virus
• HIV
• Rubella
• Syphilis

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Antenatal fetal screening

• Structural anomalies (USS 18-20 wks)
• Downs syndrome
• Nuchal translucency (NT)
• Combined test (NT, hCG, PAPP-A)
• Triple test (hCG, AFP, uE3)
• Quadruple test (hCG, AFP, uE3, inhibin A)
• Integrated test (NT, PAPP-A hCG, AFP, uE3,
  inhibin A)
• Serum integrated test (PAPP-A hCG, AFP, uE3,
  inhibin A)

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Neonatal screening - newborn check (lt72 h)

• Congenital malformations
• Eyes
• Heart
• Hips
• Testes
• Hearing
• Otoacoustic Emissions (OAE)
• Automated Auditory Brainstem Response test (AABR)

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Neonatal screening bloodspot 1

• Phenylketonuria (PKU)
• Congenital hypothyroidism
• Sickle cell thalassaemia
• Heel prick test day 5-8
• Over 600,000 newborns screened per year
• Approx 250 affected babies identified per year
• gt99 coverage

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Neonatal screening bloodspot 2

• Cystic Fibrosis
• IRT (immuno-reactive trypsinogen) followed by
  two-stage DNA screen if IRTgt99.5 centile
• if one mutation found or no mutation but v high
  initial IRT, blood taken for further IRT
  measurement
• currently 20 of newborns screened in England
• all newborns in Northern Ireland, Wales and
  Scotland screened
• April 2007 - all newborns in UK to be screened

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National standard protocol for newborn screening
for cystic fibrosis - algorithm
Day 5 blood spot samples IRT assay
10,000
50
IRT lt 99.5th centile
IRT gt99.5th centile
DNA analysis 4 mutations
Report CF not suspected
Note 0.25 CF infants will not be identified
through screening (IRT inaccurate in meconium
ileus)
No mutation detected
Two CF mutations
One CF mutation
3
6
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DNA analysis 29 or 31 panel
0.5
One CF mutation
5.5
IRTgt99.9th centile
Refer with presumptive diagnosis of CF
IRT on 2nd blood spot
IRT on 2nd blood spot
Yes
3.5
No
Av. lt Cut-off 2
Av. gt Cut-off 2
Av. gt Cut-off 2
Av. lt Cut-off 2
Report CF not suspected
High likelihoodClinical referral
Report CF not suspected
High likelihoodClinical referral
Low likelihood Advice, counselling
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0.5
38
0.1
2.9
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Child screening

• Physical examination (6-8 wks)
• Eyes
• Hips
• Heart
• Testes
• School entry
• Hearing
• Height, weight and growth
• Vision

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Adult screening

• Chlamydia (oppurtunistic)
• Diabetic retinopathy
• Vascular
• Breast cancer
• Cervical screening
• Colorectal cancer

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Breast screening - background

• 1988 set up by DoH following recommendations of
  a working group, chaired by Professor Sir Patrick
  Forrest
• 1986 - report Breast Cancer Screening was
  published, became known as The Forrest Report
• First of its kind in the world
• 1990 - began inviting women for screening
• Mid 1990s - national coverage achieved

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Breast screening why?

• 14 million women screened so far
• 80000 cancers detected
• Report by DoH Advisory Committee published in
  1991 suggested programme would save 1,250 lives
  by 2010
• Latest research shows screening saves 1400 lives
  per year in England
• 35 decreased mortality (for every 500 women aged
  50 69 yrs screened, 1 life saved)

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Breast screening who and how?

• All women aged 50 to 70 years
• Invited every 3 years
• 1.5 million screened per year
• Method 2 view mammography

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Breast screening how much?

• 80 breast screening units across the UK
• Nationally coordinated
• Budget for programme (in England) is
  approximately 75 million 37.50 per woman
  invited or 45.50 per woman screened

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Cervical screening - background

• Mid-1960s - cervical screening began in Britain
• Mid-1980s - concern that those at greatest risk
  were not being tested, and that those who had
  positive results were not being followed up and
  treated effectively
• 1988 - The NHS Cervical Screening Programme was
  set up ? DoH instructed all health authorities to
  introduce computerised call-recall systems and to
  meet certain quality standards

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Cervical Screening why?

• Detects early abnormalities which, if left
  untreated, could lead to cervical cancer
• Almost 4 million women screened per year
• In 2001/2002- 81.6 eligible women screened ?
  possible 95 reduction in mortality long term

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Cervical Screening who?

• All women aged 25 to 64 years
• Every three to five years depending on age (as
  per advice by Cancer Research UK)
• National recommendations will be changed as
  follows

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Cervical Screening how?

• Smear test
• Spatula swept around cervix
• Cells smeared onto slide
• Examined under microscope
• Liquid Based Cytology (LBC)
• Brush inserted into cervix
• Head of brush either placed in vial of
  preservative fluid or cells washed of into fluid
• Cells spun down and obscuring material removed
• Thin film on slide inspected by microscope
• Reduction in inadequate tests ? reduced patient
  anxiety, workload and cost

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Cervical Screening how much?

• Estimated cost 157 million per year in England
• Changeover to LBC estimated to cost 10 million
• Nationally coordinated
• PCTs commission cervical screening from the
  overall allocation received from the DoH
• Regional directors of public health responsible
  for quality assurance of network in their region

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Colorectal cancer screening - background

• national programme to be phased in from 2006 over
  3 years
• Wolverhampton to have first screening centre
• 14 centres by spring 2007
• will eventually be gt90 screening centres across
  the country administered from 5 regional
  programme hubs

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Colorectal cancer screening why?

• major public health problem - second most common
  cause of cancer deaths in UK
• aim to reduce death rates by finding and treating
  bowel cancer early
• deaths from bowel cancer could drop by 15 as a
  result of screening
• nationally, screening for bowel cancer could save
  approximately 1,200 lives each year
• patients whose cancer is discovered early have
  more treatment options and better long term
  outlook

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Colorectal cancer screening who?

• All men and women aged 6069 years
• Every 2 years

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Colorectal cancer screening how?

• Faecal Occult Blood
• Sample taken at home then sent to lab for
  analysis

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Colorectal cancer screening how much?

• FOB test costs 5
• 2 of all tests are positive ? subsequent
  diagnostic colonoscopy 127

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Vascular

• National Service Framework for Coronary Heart
  Disease in England recommends priority given to
  the identification of people at high risk of
  coronary heart disease so can be given systematic
  follow-up and offered advice and treatment to
  reduce the risk of recurrent infarction
• screening is not recommended for people at low
  risk of coronary heart disease.
• National Screening Committee has integrated these
  recommendations with those of the NSF for
  Diabetes to create the Diabetes, Heart Disease
  and Stroke Prevention Project (being piloted in 8
  inner city primary care trusts, where need is
  greatest)

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Conditions not screened for 1

• Antenatal
• Bacterial vaginosis
• Chlamydia
• Cystic Fibrosis
• CMV
• Diabetes
• Domestic violence
• Familial dysautonomia
• Fragile X
• Genital Herpes
• Hepatitis C
• HTLV-1
• Postnatal depression
• Preterm labour
• Streptococcus B
• Thrombocytopenia
• Thrombophilia
• Toxoplasmosis

• Newborn
• Amino acid metabolism disorders
• Biliary atresia
• Biotidinase deficiency
• Cannavans diseased
• Congenital adrenal hyperplasia
• Fatty-acid oxidation disorders
• Galactosemia
• Gauchers disease
• Medium Chain Acyl CoA Dehydrogenase Deficiency
  (MCADD)
• Muscular dystrophy
• Neuroblastoma
• Organic metabolism disorders
• Thrombocytopenia

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Conditions not screened for 2

• Child
• Autism
• Dental Disease
• Development Behaviour
• Hypertension
• Hypertrophic cardiomypathy
• Hyperlipidaemia
• Iron deficiency anaemia
• Lead poisoning
• Obesity
• Speech Language delay
• Scoliosis

• Adult
• AAA
• Alcohol problems
• Alzheimers disease
• Atrial fibrillation
• Cancers Anal, Bladder, Lung, Oral, Ovarian,
  Prostate, Stomach, Testicular
• Deafness
• Depression
• Diabetes
• Domestic violence
• Glaucoma
• Haemochromatosis
• Hepatitis C
• Hyperlipidaemia
• Osteoporosis
• Renal disease
• Thrombophilia
• Thyroid disease
• Vision

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References

• www.screening.nhs.uk
• Screening for Breast Cancer in England Past and
  Future, Advisory Committee on Breast Cancer
  Screening, 2006 (NHSBSP Publication no 61)
• Breast Cancer Screening 1991 Evidence and
  Experience since the Forrest Report, Department
  of Health Advisory Committee, NHS Breast
  Screening Programme 1991
• 7th Handbook on Cancer Prevention, IARC, Lyons
  2002
• P Sasieni, J Adams and J Cuzick, Benefits of
  cervical screening at different ages evidence
  from the UK audit of screening histories, British
  Journal of Cancer, July 2003
• http//www.cancerscreening.nhs.uk
• http//www.rcog.org.uk/resources/Public/pdf/Antena
  tal_Care_summary.pdf

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