preventative medicine and screening

Question 1

what is secondary prevention?

Answer 1

it is actions to detect the disease early to prevent the emergence of symptoms and complications - prophylactic treatment and screening for asymptomatic disease

Question 2

what is screening?

Answer 2

it is the testing of a population for a condition who do not have recognised symptoms

Question 3

what is the difference between a screening and diagnostic test?

Answer 3

screening offers individuals information as to whether they are high or low risk. If they are high then they are offered a diagnostic test to see if they have the condition or not

Question 4

what are current UK screening programmes?

Answer 4

bowel, breast and cervical cancer, AAA, diabetic eye, foetal anomaly and infectious disease in pregnancy, newborn and infant physical, newborn hearing and blood spot and sickle cell and thalassaemia

Question 5

what are advantages of screening?

Answer 5

can make decisions about health, early treatment which can be more effective, reduced development and mortality and can detect problems before are noticed

Question 6

what is AAA?

Answer 6

it is an enlargement of the abdominal aorta and weakening of the artery wall

Question 7

what are risk factors for AAA?

Answer 7

smoking, diabetes, high blood pressure and high cholesterol

Question 8

what is the epidemiology for AAA?

Answer 8

most common in men over 65 and 5000 deaths per annum in UK

Question 9

what is the screening for AAA?

Answer 9

it is offered to men over 65 and is a non invasive USS. It has led to a 50% reduction in deaths over ten years

Question 10

what are disadvantages of screening?

Answer 10

not 100% accurate
false positives - anxiety, overtreatment and harmful procedures
false negative - false reassurance and no treatment
can lead to difficult decisions

Question 11

who decides what screening is done?

Answer 11

The UK screening committee (criteria)

Question 12

what is the criteria for screening?

Answer 12

economically balanced in relation to medical care as a whole
benefits outweigh harm
important health condition as judged by frequency and severity
intervention available
socially, clinically and ethically acceptable to health professionals and public
simple, safe, precise and validated
reduces morbidity/mortality

Question 13

why was the prostate screening removed?

Answer 13

cannot differentiate between slow and fast growing cancer
treatment had significant risk
around 85% of positives were false
around 15% of negatives were false
cannot therefore be justified in low risk populations

Question 14

what is down syndrome?

Answer 14

it is caused by the addition of chromosome 21 - trisomy 21. It is associated with learning disability and other severe health conditions and occurs in 1 in 700 live births

Question 15

what is the screening for down syndrome?

Answer 15

every pregnant women offered test from 10-14 weeks of pregnancy - diagnostic that gives a 0.5% chance of miscarriage

Question 16

what are the rules for abortion around down syndrome?

Answer 16

termination of pregnancy is legal until term

Question 17

what are the ethics around screening?

Answer 17

cost effectiveness, benefit vs harm, risk and severity, prevention, effective intervention and morbidity

Question 18

what is sensitivity?

Answer 18

the proportion of people with a disease that are identified as having the disease with a positive test result

Question 19

what is specificity?

Answer 19

the proportion of people without a disease who are correctly reassured by a negative result of a test

Question 20

what is the positive predictive value?

Answer 20

the probability that a person with a positive test result has the disease

Question 21

what is the negative predictive value?

Answer 21

it is the probability that a person with a negative result does not actually have the disease

Question 22

what is DCIS?

Answer 22

ductal carcinoma in situ

Question 23

what is the issue with screening?

Answer 23

it is not clear the extent to which diagnosis and treatment of DCIS may prevent the occurrence of invasive breast cancer in the future

Question 24

what did Duffy et al 2016 study show?

Answer 24

the ecological study showed that for every 3 screen-detected cases of DCIS, in the next 3 years there was one fewer invasive cancer results

Question 25

what is a true positive and false positive?

Answer 25

true - screen detects and is actually there, false - screen protects and is not actually present

Question 26

what is a false and true negative?

Answer 26

false - the screen says there is no disease but there is

true - no disease on screen and actually no disease

Question 27

what is the sensitivity calculation?

Answer 27

true positive/(true positive+false negative)

Question 28

what is the specificity calculation?

Answer 28

true negative/ (true negative+ false positive)

Question 29

what is the calculation for PPV?

Answer 29

true positive/(true positive+false positive )

Question 30

what is the calculation for NPV?

Answer 30

true negative/(true negative + false negative )