11 - Prevention and Screening Flashcards
What is CBR and ROI?
- Cost Benefit Ratio: Benefit divided by cost
- Return on Investment: Benefit minus cost
What is primordial prevention?
Population level that tries to eliminate risk factors, e.g not bringing any sugar into England
What are the different levels of prevention and what population do they target?
What prevention is giving aspirin after and MI?
Tertiary
What is the socioecological model of prevention?
Different levels of risk factors, e.g a structres and system risk of domestic violence is gender inequality
Why is tertiary prevention sometimes misdiagnosed?
Anything that happens after symptoms have occured. Minimises suffering and lessens impairment.
What is an impairment?
Any loss or abnormality of anotomical, physical or physiological structure or function
What is disability?
Any restriction or lack of ability to peform an activity in the manner or within the range considered normal for a human being
What is handicap?
A disadvantage for a given individual that limits or prevents the fulfillment of a role that is normal for that individual
What is the definition of screening?
Screening is a systematic attempt to detect an unrecognised condition by the application of tests, examinations, or other procedures to identify healthy people who may be at increased risk of disease or condition, from those who probably do not
It is not diagnostic, further tests will have to be carried out
What is the screening process?
Due to costs only the high risk have diagnostic checks
What is sensitivity of screening?
The number of cases which the test correctly detects
What is specificity of screening?
The proportion of non-cases that the test correctly detects
What is positive and negative predictive value?
+ = Proportion of positive tests that are cases
- = Proportion of negative tests that are not cases
What is the reason for screening?
Secondary prevention to give a better outcome than if the disease was detected once symptoms have developed
What are the features of test validity?
- Sensitivity
- Specificity
- PPV
- NPV
What are the two errors that a screening test can make and what can this cause?
False + = stress and lower uptake of screening in future
False - = not offered testing and false reassurance
How do you work out positive predictive value?
How do you work out negative predictive value?
What influences PPV?
Prevalence will increase the PPV
What is the effect of increasing the cut off score for high risk?
Sensitivity will decease but specificity will increase
What is the likelihood ratio?
Used to find optimum threshhold for screening test to be high risk. How much more likely is a case to have a result compared to a non case
Want high positive value, low negative value
How can you graphically assess the quality of a diagnostic test?
ROC Curve (Reciever Operating Characteristic)
What are the criteria for a screening selection?
What happens to the PPV when you screen a high prevalence population?
Will be higher
What is motivational interviewing?
Getting people to list good and bad things about their behavioru and see what barriers there may be to someone changing their behaviour
Express Empathy, Develop Discrepancy, Avoid Argumentation, Roll with Resistance, Support Self-efficacy
What are some current screening programs on the NHS?
- AAA
- Breast,cervical, bowel cancer
- Newborn hearing and heel prick
- Hep B, HIV, Downs etc
What is the bowel screening process?
Everyone over the age of 60 is sent a kit every two years. Have to smear faces on it over 3 days
What factors affect the uptake of bowel screening?
- Misunderstanding instructions
- Fear of posting in mail
- Feeling healthy
- Past negative experience of colonoscopy
- Don’t speak English
- Learning difficulties
How can we increase bowel cancer screening?
- Make booklet clearer
- Do one single test not 2 smears
Issue: cost, dont have workforce, don’t have physical capacity
How does antenatal screening for trisomies occur?
- Test in first trimester (10 to 14 weeks) to look at nuchal fold thickness, and measure maternal blood markers
- 1:2 to 1:150 risk then higher risk
- Diagnostic test offered - amniocentesis
