Screening Pt 2

Question 1

What are the 5 main issues raised by screening?

Answer 1

Alteration of usual doctor-patient contract

Complexity if screening programmes

Evaluation of screening programmes

Limitations of screening

Sociological critiques of screening

Question 2

In terms of issues raised by screening, what is the ‘alteration of the doctor-patient contract’ issue?

Answer 2

In clinical practise people self-present asking for help, so define themselves as patients

Screening targets apparently healthy people who have not sought the help of the health service with the offer of help for something they may have never thought about.

If a patient asks for help then a doctor does the best to help that patient. But if the doctor screens a healthy person to tell them they are ill, then they need to have conclusive evidence that they can help that patient.

Question 3

In terms of issues raised by screening, what is the ‘complexity of screening programmes’ issue?

Answer 3

There are many questions and debates over a screening programme.
Is the natural history understood?
How many abnormalities would regress spontaneously?
Are the ‘right’ people being screened?
Debate over whether screening has caused reduction in mortality
Over-treatment?
Psychological impact?

Question 4

Give an example to back up the ‘complexity of screening programme’ issue

Answer 4

Cervical screening
- Not a test for cancer
- Method of preventing cancer by detecting and
treating early abnormalities which if untreated could
lead to cervical cancer
- Free for women (25-64) every 3-5 years (England)

Don’t screen under 25s
- Under age of 25 invasive cancer is extremely rare,
but changes in the cervix are common
- Lesions that are destined to progress are still screen-
detectable, and those that regress won’t cause
anxiety
- Therefore avoid unnecessary investigations and
treatments, anxiety, distress, etc…

Don’t screen women over 65
- Natural history and progression of cervical cancer
means it is highly unlikely that such women will go on
to develop the disease
- Women over 65 who have never had a test are
entitled to one

The process
- Speculum opens up vagina and a spatula is used the
take a sample of cells from the cervix
- Cytology lab grades to determine what happens next
- Interpretation of results?

Results
- Most normal results
- Abnormal result:
- Not all need immediate treatment - need to strike
a careful balance
- Abnormal cells may be destroyed

Numbers - England 2013-14:

• Approx. 3.2 million women were screened
• 77.8% of eligible women screened in last 5 years
• 199,322 referrals to colposcopy were made
• Estimated to cost about £175m/year in England

Question 5

In terms of issues raised by screening, what is the ‘evaluate screening programmes’ issue?

Answer 5

Need to evaluate screening programmes:
- Screening programmes must be based on good
quality evidence
- There can be great pressure to start screening
programmes

Question 6

What are some of the difficulties about evaluation of screening programmes?

Answer 6

Lead time bias:

Length time bias

Selection bias

Question 7

Explain lead time bias

Answer 7

Early diagnosis falsely appears to prolong survival

Screened patients appear to survive longer, but only because they were diagnosed earlier

Patients live the same length of time, but longer knowing they have the disease

Question 8

Explain length time bias

Answer 8

Screening programmes better at picking up slow growing, unthreatening cases than aggressive, fast growing ones

Diseases that are detectable through screening are more likely to have a favourable prognosis, and may indeed never have cause the problem.

Could lead to false conclusion that screening is beneficial in lengthening the lives of those found positive - curing people that didn’t need curing?

Question 9

Explain selection bias in terms of evaluation difficulty for screening programmes.

Answer 9

Studies of screening often skewed by ‘healthy volunteer’ effect

Those who have regular screening likely to also do other things that protect them from disease

An RCT would help with this bias

Question 10

In terms of issues raised by screening, what is the ‘limitations of screening’ issue?

Answer 10

Screening is not a fool proof process.
It can reduce the risk of developing a conditions or its complications but it cannot offer a guarantee of protection.
In any screening programme, there is a minimum of false positive results and false negative results
The NCS is presenting screening as risk reduction to emphasis this point

Screening carries potential for harm as well as benefit
Increasing emphasis on promoting informed choices about screening
BUT
Communicating benefits, harms and risks of preventive interventions can be challenging

Question 11

In terms of issues raised by screening, what are the ‘Sociological critiques of screening’?

Answer 11

(Structural critiques)
Victim blaming
   - Individuals encouraged to take responsibility for own 
     health
   - Are all equally able to do this?
Individualising pathology
   - What about addressing underlying material causes of 
     disease?

                      (Surveillance critiques)    Individuals and populations increasingly subject to surveillance Prevention part of wider apparatus of social control

                       (Social constructionist) Health and illness practices can be seen as moral - given meaning through particular social relationships So going to screening is seen as the moral, right, sensible thing to do, and if you don't you will be seen as deviant

                           (Feminist critique) Is screening targeted at women more than men?