Public Health Screening: Programmes & Policy

Dr Gary KerrLecture for University of GlasgowMSc (Med Sci) in Medical Genetics

Objectives

• To understand the concept of a screening programme

• To describe screening programmes within a policy context

• To describe the three types of screening programmes (prenatal, postnatal, adult)

• To discuss the effectiveness of screening programmes

• To discuss the ethical and societal issues surrounding screening

What is Screening?• Process of identifying apparently healthy people who may be

at an increased risk of particular disease or condition

• Screening results are ‘presumptive’ as they do not give a diagnosis

• People with ‘high-risk’ results can be offered further testing

• Screening process must be based on ‘informed choice’

People offered the screening test

(Target population)

These people are being screened for a target condition

Uptake

In the ideal screening programme, only people with the target condition will be identified as ‘high-risk’

High-RiskLow-Risk

High-RiskLow-Risk

A slightly more realistic screening programme…

False-negative

False-positives True-positives

True-negatives

Detection Rate: % of people with the target condition who have successfully been identified by screening

UK National Screening Committee (UK NSC)

• UK NSC chaired by Dr David Walker (Deputy Chief Medical Officer for England)

• UK NSC advises the 4 UK Health Ministers on all aspects of screening and supports the implementation of screening programmes

• Provide independent & expert policy advice based on scientific research

• Only implement screening programmes that do ‘more good than harm’

Pregnancy Screening

Sickle Cell Disease & Thalassaemia Screening• Blood test within first 10 weeks of pregnancy• SCD affects shape of red blood cells• Change in shape means cells can get ‘stuck’ in small blood

vessels, causing great amount of pain. Can sometimes be fatal

• Once detected, antibiotics & immunisations can help prevent serious illness

• Thalassaemia disorders affect the body’s ability to make new red blood cells

• Can lead to severe anaemia• Early detection allows for early interventions• Thalassaemia patients need regular blood transfusions (4-6

weeks) and need regular injections & medicines for rest of their lives

Infectious Diseases Screening

• Blood test at 8-12 weeksInfectious Disease

Description

Rubella Generally a mild illnessMost people immunised against rubella in childhoodBut, some people have not been immunisedRubella-infected mothers can pass rubella onto babyCan lead to deafness in the baby

Hepatitis B Hep B is a virus that affect the liverVirus can be carried in the blood for many years without symptomsCan lead to severe liver disease if untreated

Syphilis Rare sexually transmitted infection that can damage health of the baby

HIV Can damage the immune system and destroy the body’s defences against infection and diseaseHIV positive mothers can pass infection onto the baby during pregnancy, birth or breastfeeding

Infectious Diseases Screening

• Routine blood test at 8-12 weeks

• Early detection and simple treatments can reduce risks to both the baby and the mother

Down Syndrome • DS is a genetic disorder characterised by an extra copy (i.e. 3

copies) of chromosome 21

• DS characterised by learning difficulties and distinct physical clinical features

Down Syndrome Screening

1. Blood test at 11-14 weeks

2. Early Pregnancy Ultrasound Scan (Nuchal Translucency Scan) at 11-14 weeks

3. Mid-Pregnancy Ultrasound Scan (Fetal Anomaly Scan) at 18-21 weeks

Fetal Anomaly Screening• Mid-Pregnancy Ultrasound Scan (18-21 weeks)• Aim of the fetal anomaly scan is to identify:

– Anomalies that are incompatible with life;– Anomalies associated with high morbidity and long-term

disability;– Fetal conditions with the potential for intrauterine therapy;– Fetal conditions that will require postnatal investigation or

treatment • This scan can detect cleft lip; Down, Edwards & Patau

syndromes; lethal skeletal dysplasia; open spina bifida and ancephalies.

• In Scotland in 2012, this screen detected 44.7% of all fetal anomalies

• Detection rates vary for different anomalies

Prenatal Diagnostic Testing• Screening results are ‘presumptive’• Diagnostic testing allows for conclusive diagnosis• Decisions regarding diagnostic testing must be based on

informed choice

Amniocentesis Chorionic Villi Sampling (CVS)

The procedure A needle is injected into the womb to take a sample of amniotic fluid (fluid that surrounds the fetus)

A sample of chorionic villi cells are taken from the woman’s placenta for analysis

Miscarriage rate as a direct result of the procedure

1 in 100 1 in 50

Time at which procedure can be carried out

15-16 weeks of pregnancy 10-14 weeks of pregnancy

Newborn Screening

Newborn Blood Spot ScreeningScottish Newborn Screening Laboratory (Southern General

Hospital, Glasgow) commissioned by NSD to:

– Screen blood samples of all babies born in Scotland (around 60,000 per year)

– Ensure reporting of all results to the proper authorities and prompt referral of all positive cases for treatment

– Provide data on incidence of conditions tested

– Review new technology with a view to incorporating new methods and technologies into the screening programme

Newborn Blood Spot Screening• Formerly known as ‘Guthrie Test’

• Identifies newborns with rare but serious conditions

• Early treatment can improve health and prevent severe disability or death

• Blood spot test offered to all parents of newborn babies

• Midwife pricks heel of newborn baby and sends a few drops of blood to the Newborn Screening Laboratory for analysis

• Tests for 5 conditions

Genetic Condition Incidence for babies born in Scotland

Description

Phenylketonuria (PKU)

1 in 8000 Inability to digest Phenylalanine (fond in most foods). Can be treated with a very strict diet

Cystic Fibrosis (CF) 1 in 2500 1 in 25 people in Scotland are CF carriers. Affects the lungs and causes chest infections and problems digesting food

Sickle Cell Disorder (SCD)

1 in 2500 For those not already detected in prenatal screen

Congenital Hyperthyroidism (CHT)

1 in 3500 Baby doesn’t produce enough thyroxine hormone. Thyroxine needed for mental & physical development

Medium Acetyl-CoA Dehydrogenase Deficiency (MCADD)

1 in 10,000 Inability to break down certain fats to make energy. Very problematic when baby has an illness and cannot eat

Newborn Blood Spot Screening 2012• Scottish Newborn Screening Laboratory analysed 58,686 blood spots

• 91 blood spots were presumptive positive:– 8 for PKU– 41 for CHT– 32 for CF– 9 for SCD– 5 for MCADD

• These 91 cases referred for diagnostic testing

• Screening was declined by parent/guardians in:– 21 cases for PKU, CHT, MCADD– 23 cases for CF– 27 cases for SCD

Newborn Hearing Screening

• Universal Newborn Hearing Screening Programme is the official hearing test for newborns

• Usually performed before a baby leaves hospital

• Hearing loss in one or both ears affects around 1 in 1000 babies

• Most of these babies born into families with no family history of hearing loss

• Results given at the time of the test

Newborn Physical Examination

• NHS Newborn and Infant Physical Examination (NIPE) Screening Programme ONLY applies to England

• Head to toe examination of the baby to check for any abnormalities at 72 hours after birth and then again at 6-8 weeks

• Includes a detailed examination of the eyes, heart, hips and testes in boys

• In Scotland, this is not an official screening programme, but is routinely carried out throughout NHS Scotland

Adult Screening

Bowel Cancer Screening• Third most common cancer in Scotland (after lung and breast cancers)

• Second most common cancer in men in Scotland

• Scotland has higher rate of bowel cancer than any other Western country

• Scottish Bowel Screening Programme offers bowel test to everyone aged 50 – 74 every 2 years

• England & Wales: People aged 60 – 74 offered screening every 2 years

• Northern Ireland: People aged 60 – 69 offered screening every 2 years

• Younger people with family history of bowel cancer may be offered screening at an earlier age

Bowel Cancer Screening• Looks for early signs of cancer in otherwise healthy

people who have no symptoms

• Relatively straightforward test – carried out at home

• Faecal occult blood (FOB) test – requires small samples of bowel motions

• Easy-to-use kit can be sent back to local health board free of charge for analysis

• Testing looks for blood in stools

Bowel Cancer Screening

• For every 1000 people tested, around 20 will have an abnormal result

• Referral for colonoscopy for diagnostic test

• From these 20 referrals, around 2 people will have bowel cancer

• Regular bowel screening shown to reduce risk of dying from bowel cancer by 16%

Bowel Cancer Screening in Scotland• Recent figures show uptake is 53.7%

• Uptake higher in females (57.2%) than in males (50.0%)

• Uptake affected by social factors: only 37.8% of males in most deprived areas of Scotland take the screening test

• Bowel cancer rates vary geographically across Scotland:– Highest rates are in Glasgow & Lanarkshire

• Screening programme detects twice as many cancers in men than in women

• Screening can also detect small growths in the bowel called polyps

Scottish GovernmentBowel Cancer Screening Awareness

http://www.youtube.com/watch?v=UrwA_p8H6WY

Breast Cancer in Scotland

• Most common cancer diagnosis for women in Scotland

• Second most common cause of cancer death in women in Scotland (after lung cancer)

• In Scotland, over 4000 women diagnosed with Breast Cancer every year

– 1000 women in Scotland die of breast cancer every year

– 10 men in Scotland die of breast cancer every year

Scottish Breast Screening Programme• Mammogram offered to women aged 50-70 every 3 years

• Younger women with a family history of breast cancer may also be invited for regular screening

• Breast Screening Programme provided by 6 Breast Screening Centres (Aberdeen, Dundee, Edinburgh, Glasgow, Inverness & Irvine)

• Supported by 19 mobile units for remote areas (80% of breast screening takes place on mobile units)

• In 2012, breast screening programme detected 1700 cases of breast cancer

• Uptake of breast cancer screening is 74.9%

• Around 9 cancers detected for every 1000 screens performed

Scottish GovernmentBreast Cancer Screening Awareness

http://www.youtube.com/watch?v=lxQdfB-no50

Cervical Cancer Screening• Most common type of cancer in women aged under 35 in Scotland

• ‘Pap Smear Test’ offered to women aged 20-60 every 3 years

• Smear test can detect changes to a woman’s cervix which could develop into cancer

• Cervical Cancer Screening estimated to save around 5,000 lives each year in the UK

• This screening programme prevents 8 out 10 cervical cancers from developing in the first place

• Uptake is 73.6%

• 9.2% of those screened are referred for diagnostic testing

Cervical Cancer Vaccination Programme• Human Papillomavirus (HPV) can cause cervical cancer

• HPV is a very common virus and can spread via sexual intercourse

• There are different strains of HPV

• Two strains of HPV cause 70% of cervical cancers

• HPV vaccination introduced in Scotland in 2008 for girls aged 12-13

• Girls receive 3 doses over a 6 month period in order to provide the best protection

• As of September 2012, the new vaccination protects against the 2 most dangerous strains plus another 2 HPV strains and genital warts

• The vaccination does not protect against all types of HPV and therefore regular screening is still important

• Uptake of vaccination is around 90%

Cervical Cancer Vaccination Programme

Diabetic Retinopathy Screening

• Approx. 150,000 people in Scotland with diabetes

• Around 5-10% of diabetics have a sight-threatening retinopathy

• Retinopathy can cause severe damage to the eye and can result in blindness

• Diabetic retinopathy is the biggest cause of blindness and visual impairment in Scotland amongst people of working age

• Rising prevalence of diabetes means that Diabetic Retinopathy it is likely to become a major health and economic problem

Diabetic Retinopathy Screening

• Screening Programme offers annual screening to everyone with diabetes aged 12 and over

• Uptake of the eye screen in 2011/12 is 84.8% despite a 4% increase in those eligible from the previous year

• In 2011/12, there were 238,383 diabetic retinopathy screens

• 3.9% of those screened were referred to opthalmology for further examinations

Abdominal Aortic Aneurysm (AAA) Screening

• In July 2012, the Scottish Government announced its intention to roll out an AAA screening programme

• To be fully rolled out by December 2013

• AAA is an enlarged part of the aorta within the abdomen

• It has no symptoms, unless it bursts – which is usually fatal

• 284 men in Scotland die from AAA each year

• Screening will be offered to men aged 65

• 95% of ruptures occur within this group

• Screening test will use ultrasound to measure the size of the aorta

• AAA screening programme aims to:– Prevent around 170 deaths by AAA each year– Shift balance of care from emergency treatment to disease

management through early diagnosis

• Surgery and/or Lifestyle changes can reduce risk of a rupture

• Men with small or medium-sized AAA will be called back for regular surveillance

Abdominal Aortic Aneurysm (AAA) Screening

International Comparisons • Pre-marital screening required in some countries (e.g. Saudi

Arabia) for a marriage certificate to be issued

• UK requires anyone entering from India to be screened for Tuberculosis (formal requirement since November 2012)

• Within the EU, large variations in screening policy:

– In Greece, amniocentesis offered to ALL pregnant women aged 35 or over

– In Italy, no national screening programmes for breast, cervical or bowel cancer, but local initiatives do screen people

– No specific policy for Down syndrome screening in Germany

“Screening must do more good than harm”

• NHS in England undertaking Review of Breast Screening

• Problems with ‘False-Positive’ – can cause anxiety

• Problems with ‘False-Negative’ – False reassurance can prevent people from visiting their GP

• Screening is not for people with symptoms of the target condition

• Screening must be based on ‘Informed Choice’ and an understanding about the screening process

• Issues with high resource costs & potential over-treatment

Further Readingwww.scottish.parliament.uk/parliamentarybusiness/54023.aspx